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Volume 38,Issue 2
  • Ecological risk of urbanization and risk management
  • Authors:LÜ Yonglong, WANG Chenchen and CAO Xianghui
  • Abstract:With urbanization, not only population is gathering to the city and urban landscape is expanding, but also social structure is changing greatly. At the same time, urban modes of production and consumption are spreading to a wider area. However, with over-concentrated population and extensive expansion of cities, "urban diseases" such as traffic congestion, air pollution, waste accumulation and epidemics occur frequently. City consumes natural resources excessively and discharges a large amount of pollutants to the surrounding environment, which will change the original structure and function of regional ecosystem, and then severe ecological risks emerge and the sustainable development of urban ecosystem is constrained. The ecological risks of urbanization have been gradually getting more attention, but the concrete definition and impacts of urban ecological risks are still unclear. Therefore, this paper defines all kinds of ecological risks and analyses their main influencing factors in the process of urbanization. The major methods for ecological risk identification and assessment are also expounded, and some suggestions for ecological risk management of urbanization are presented.
  • DownLoad:Ecological risk of urbanization and risk management.PDF
  • The ecological value of local knowledge
  • Authors:WANG Zhifang and SHEN Nan
  • Abstract:The value of local knowledge in solving ecological problems has received considerable attention in foreign countries, but not yet in China. This paper summarizes the relevant worldwide literature about local knowledge and demonstrates that research on local knowledge has been gradually increasing in recent years and that studies abroad are significantly greater in number and deeper in content than domestic studies. Overall, the ecological value application of local knowledge can be summarized in four areas:background knowledge, basic data, future potential, and ecological management. Domestic research on local knowledge is merely on the level of description, especially, the description of background knowledge. In contrast, Foreign research is more focused on how to use local knowledge to provide data, provide new planning and technical methods, and strengthen the role of local knowledge in ecological management. At the end of this paper, we sum up the concrete role of local knowledge in ecological applications, and propose a general framework to use local knowledge in ecological solutions and guide relevant scientific research and practices in China. As shown in foreign research, there are many opportunities for the application of local ecological knowledge in China. As an effective complement to universal knowledge, local knowledge should be fully involved in the entire process of data gathering, decision-making, and management. We put forward some difficulties in the future development and application of local knowledge in China, but expect that local knowledge will soon play its valuable role in scientific planning and resource management.
  • DownLoad:The ecological value of local knowledge.PDF
  • Review on analytical framework of eco-compensation
  • Authors:LIU Di, HU Zhentong and JIN Leshan
  • Abstract:Eco-compensation has attracted increasing interest as a mechanism to translate external, non-market value of the environment into real financial incentives for local actors to provide environmental services. An international review of eco-compensation, therefore, is essential to perfect institution construction and to improve the practice of China's eco-compensation. This paper begins with a brief introduction of eco-compensation, namely its definition, its basic logic, and some of its key features. We then proceed to review some core issues in the analytical framework of eco-compensation, such as subject, object, rates, conditionality, efficiency, and the relationship between eco-compensation and poverty alleviation. Finally, we conclude by suggesting how to improve institution construction of China's eco-compensation using international practice and lessons. In order to improve eco-compensation mechanism in China, efforts should focus on providing entry points for private sector investment in the environment, revealing the mechanism of ecosystem services' formation and its supply, establishing the gauge of eco-compensation rates, ensuring the conditionality of eco-compensation, setting up baseline and targeting, and finally, studying how eco-compensation contributes to the poverty alleviation.
  • DownLoad:Review on analytical framework of eco-compensation.PDF
  • Impact of biochar application on carbon sequestration, soil fertility and crop productivity
  • Authors:XU Min, WU Jun, ZHANG Xiaohong and YANG Gang
  • Abstract:Global warming and food security have been significant issues in the field of sustainable development. Several studies have shown that biochar amendments markedly contribute to mitigating global warming and food crises and produce beneficial win-win effects. This is mainly because of the high stability and carbon content of biochar, which can enhance the storage of soil carbon and the physical and chemical properties of soil, consequently resulting in increased yields. Therefore, the objective of the present work was to examine previous studies on the efficacy of biochar as a soil amendment and to analyze the intrinsic factors that affect soil carbon reserve and agronomic benefits (including:feedstock, pyrolysis temperature, application rate and soil type). On the basis of the results obtained, a suitable application criterion was proposed, which has shown potential efficiency in carbon sequestration as well as agronomic benefits:biochar derived from pyrolysis of biomass from forestry and harvest residues at a temperature of 300-700℃, with a relatively low dosage of no more than 5%. Finally, we propose future research directions for a better understanding of the effects of biochar on carbon sequestration potential, soil fertility and crop growth.
  • DownLoad:Impact of biochar application on carbon sequestration, soil fertility and crop productivity.PDF
  • A method for forecasting first-flowering dates of cherry blossoms
  • Authors:SHU Si, XIAO Mei and CHEN Zhenghong
  • Abstract:The prediction of flowering date of Japanese cherry blossoms has an economic value on the local tourism industry, which could help the local government and tourists manage and arrange the tourism time. In this study, we investigated the prediction methods of flowering dates of Japanese cherry blossoms, and developed a new prediction method to improve accuracy. First, a 36-year-old (1981-2016) dataset of flowering dates of Japanese cherry blossoms at Wuhan University Campus associated with meteorological data was used for developing a method of forecasting the first-flowering date of cherry blossoms. The first-flowering date of Japanese cherry blossoms was determined by linear regression and the trend of flowering dates over the last 36 years. The annual variation in the first-flowering dates was large, making the trend non-significant. The average of flowering date, in days of the year, was 73.3, which corresponded to March 14-15 (March 13-14 in a leap year). A series of sensitive studies on active accumulated temperature were performed to investigate the method of improving the forecast equation of the first-flowering date. We calculated the active accumulated temperature from January 1 and February 1 to a series of possible flowering dates, such as February 25, February 28 (February 29 in a leap year), March 5, March 10, and March 15, and the results indicated that the correlation between the active accumulated temperature and the first-flowering dates was significantly negative, and thus can be used as a factor in the cherry blossom forecasting equation. The results also showed the forecast accuracy was significantly improved with active accumulated temperature rather than accumulated sunshine hours as a predictor in the prediction equation. Compared to the prediction using the average temperature, the active accumulated temperature method is more advantageous for prediction accuracy, and the better result is achieved when the prediction is made close to the real flowering date. We also discuss the prediction method that involved the accumulated sunshine hours, because the first-flowering dates were negatively correlated with the accumulated sunshine hours. This method, however, was not effective in improving the prediction accuracy and requires further investigation.
  • DownLoad:A method for forecasting first-flowering dates of cherry blossoms.PDF
  • Spatial patterns of ecosystem hydrological regulation services and factors affecting them in the Yangtze River Basin: sub-watershed scale analysis
  • Authors:LIAO Wenting, DENG Hongbing, LI Ruonan and ZHENG Hua
  • Abstract:Hydrological regulation is one of the services provided by watershed ecosystems. For watershed ecosystem conservation and restoration and reasonable development of watershed water resources, it is important to identify the spatial pattern of watershed ecosystem hydrological regulation service and its driving forces. Many studies have been conducted at the ecosystem and landscape scale on the influence of different vegetation types and landscape patterns on hydrological regulation; such studies have played an important role in furthering the understanding of the processes and mechanisms of the hydrological regulation service in the ecosystem. At the basin scale, hydrological regulation services were affected comprehensively by many factors, including ecosystem characteristics, water conservancy facilities, water used by humans, and so on, and these influences have scale effects. Presently, owing to the lack of comprehensive studies of the systematic ecosystem at the river scale, it is still difficult to evaluate ecosystem effects on regional hydrological processes from a macro perspective. In addition, few studies have explored how to represent and understand ecosystem water regulation services at the river scale as well as to identify influential factors that have differing effects on the water regulation service of the ecosystem at the river scale. Thus, a study on the space variation regularity of hydrological regulation services and its diving force is necessary. We used as a case study the Yangtze River Basin, where flooding occurs frequently, as to study the spatial patterns of ecosystem hydrological regulation services and factors affecting it, by using the variation coefficient method and multi-variable statistics methods. The results showed that, in the Yangtze River Basin, ecosystem hydrological regulation services presented significant spatial heterogeneity at the sub-watershed scale. The sub-watersheds in Jinshajiang and Hanjiang watersheds, where dense hydropower engineering facilities are located and the coverage of natural vegetation is 71%, had the highest regulating capacity of hydrology. The difference between the coefficients of variance of precipitation and runoff was 0.477. In contrast, sub-watersheds with high population density and high proportion of cropland in Jialingjiang watershed had the lowest regulating capacity of hydrology and the difference between the coefficients of variance of precipitation and runoff was -0.474. The factors primarily affecting sub-watershed ecosystem hydrological services include reservoir volume, natural vegetation proportion, cropland proportion, and population density. Reservoir volume and natural vegetation proportion had positive effects on sub-watershed ecosystem hydrological services, while cropland proportion and population density had negative effects. Reservoir volume had the highest contribution to the heterogeneity of sub-watershed ecosystem hydrological services (58.85%). Our results facilitate a better understanding of the spatial heterogeneity of sub-watershed ecosystem hydrological services in Yangtze River Basin, and could also provide a scientific basis for sub-water ecosystem conservation and restoration, as well as the improvement of sub-watershed ecosystem hydrological regulation services.
  • DownLoad:Spatial patterns of ecosystem hydrological regulation services and factors affecting them in the Yangtze River Basin: sub-watershed scale analysis.PDF
  • Evaluation of changes in the ecosystem services of Jiaozhou Bay coastal wetland
  • Authors:SHANG Huimin, XI Min, LI Yue, KONG Fanlong and WANG Sen
  • Abstract:Jiaozhou Bay in Qingdao, as a typical coastal wetland in China, was selected as a case study to scientifically evaluate the changing characteristics of Jiaozhou Bay coastal wetland ecosystem services and clarify their drivers. The valuation of ecosystem services and an integrated method of economy and ecology were applied to estimate the value of the Jiaozhou Bay coastal wetland ecosystem. The ecosystem service functions of Jiaozhou Bay coastal wetland were divided into three main categories, namely, provisioning, regulating, and cultural services. The above three categories were further subdivided into 12 subcategories. The analysis of drivers was based on the evaluation. The main functions of Jiaozhou Bay coastal wetland are climate regulation and provision of aquatic products, the values of which account for more than 90% of the total ecosystem service value. The main service category of Jiaozhou Bay coastal wetland is the regulating service, the value of which accounted for more than 60% of the total ecosystem service value. Total value of ecosystem services for Jiaozhou Bay coastal wetland in 2005, 2010, and 2015 was 1419.73×107, 1343.91×107, and 1239.23×107 RMB, respectively,showing a decreasing trend. The reduction in wetland area and the degradation of wetland function are the main factors leading to the downward trend in the service value of coastal wetland ecosystem in Jiaozhou Bay. Unreasonable reclamation, overdevelopment of biological resources, and severe pollution of water are the factors that result in the reduction and degradation of wetland. Adverse change in climate conditions is the natural factor contributing to the further deterioration of the wetland environment. It is necessary to strengthen natural resource conservation and ecological restoration in Jiaozhou Bay coastal wetland by using ecosystem service value as a guide and taking assessment results into account in the decision-making process.
  • DownLoad:Evaluation of changes in the ecosystem services of Jiaozhou Bay coastal wetland.PDF
  • Analysis of Eco-environmental vulnerability characteristics of Hanzhong City, near the water source midway along the route of the south-to-north water transfer project, China
  • Authors:WANG Zhijie and SU Yuan
  • Abstract:South-to-north water transfer project is a large project aimed at alleviating the serious water resource shortage in northern China. The eco-environment quality of the water source area is directly related to water quality, safety, and long-term operation of the water transfer project. Further, it has important effects on regional, social, and economic development. In the present study, the eco-environmental vulnerability of Hanzhong City, which is located midway along the route of the south-to-north water transfer project, was quantitatively evaluated by using "pressure-state-response" model and spatial principal component analysis based on remote sensing and GIS technology. The results showed that:1) the eco-environmental vulnerability of Hanzhong City was at a medium level and was determined by the interaction of human activities and natural environment. The elevation, annual average precipitation, annual average temperate, per capita gross domestic product (GDP), and soil erosion intensity were the main driving factors. 2) In addition, the eco-environment vulnerability varied with altitudinal gradient. Vulnerability of the medium and high-medium mountain areas was higher than that of the high mountain area, and it was low in the low mountain and hill-gully areas. 3) Among the administrative divisions, the areas with high eco-environment vulnerability were mainly distributed in the Zhenba, Xixiang, Foping, Lueyang, and Ningqiang counties; the areas with low vulnerability were located in the Hantai district. 4) The regional eco-environmental vulnerability of Hanzhong City had strong spatial autocorrelation. The spatial variation was larger in the direction of 45° and 135°. It could provide theoretical and scientific basis for ecological restoration and planning of regional sustainable development of the water source midway along the route of the south-to-north water transfer project.
  • DownLoad:Analysis of Eco-environmental vulnerability characteristics of Hanzhong City, near the water source midway along the route of the south-to-north water transfer project, China.PDF
  • Primary production of periphyton and their relationship to water quality in Baiyangdian Lake, China
  • Authors:MA Muyuan, CUI Lijuan, ZHANG Manyin, Wang Xuemei and YU Yilei
  • Abstract:Estimation of algal primary production is important for understanding the energy flow in aquatic ecosystems. Periphytic algae are believed to be the major primary producers in lakes, especially in macrophyte-dominated lakes. However, there have been relatively few studies on periphyton primary production than those on phytoplankton in lakes. We studied periphyton in eight different disturbed sites in Baiyangdian Lake during four seasons. Biomass was measured in the laboratory using sampled periphyton, and the metabolism of shallow epiphytic and epipelic algal communities in Baiyangdian Lake was measured using changes in dissolved oxygen in chambers in situ. The relationship between the metabolism of periphyton (epiphyton and epipelon) and water physicochemical parameters was analyzed. The results showed that chlorophyll a (chla) concentrations of epiphyton and epipelon varied from 34.83 to 245.22 μg/cm2 and from 26.08 to 297.40 μg/cm2, and the ash-free dry weights (AFDW) varied from 0.46 to 5.21 g/m2 and 0.61 to 5.81 g/m2, respectively, at different sampling times. The biomass of periphyton was the highest in August, and were the lowest in April and November. In April and November, the chla of epiphyton was significantly higher than that of epipelon, and significantly lower than that of epipelon in June and August. Biomass varied significantly among sites. Both chla and AFDW of two periphytons were significantly higher in polluted areas (inlet and Nanliuzhuang) than in clear water areas (Shaochedian and Caiputai). Annual gross primary productivity (GPP) of epiphyton and epipelon in Baiyangdian Lake was 494.20 and 474.45 mgC m-2d-1, respiratory rate(R) was 522.63 and 508.98 mgC m-2d-1, and net primary productivity (NPP) was -28.44 and -34.52 mgC m-2d-1 in 2014 and 2015, respectively. The distribution of periphyton metabolism in Baiyangdian Lake exhibited significant temporal and spatial variation. GPP of periphyton was the highest in August, and the lowest in April and November, similar to biomass. The spatial distribution of periphyton GPP exhibited a decreasing trend from west to east. The NPP values were positive in clear water areas, indicating that the periphyton in these areas were autotrophic communities, whereas the NPP values were negative and the periphyton communities were heterotrophic in polluted areas. Multivariate ordination techniques were used to analyze the effects of water quality on the periphyton biomass and primary production using CANOCO version 4.5. The results of redundancy analysis (RDA) with forward selection indicated that total phosphorus, chlorophyll a, permanganate index, ammonia nitrogen, water temperature, Secchi Disc depth, dissolved oxygen, and N/P ratio were the most important environmental factors affecting periphyton primary productivity during the study period. Significantly positive correlations occurred between GPP and water trophic status.
  • DownLoad:Primary production of periphyton and their relationship to water quality in Baiyangdian Lake, China.PDF
  • Beta diversities of ground-beetle assemblages in two broad-leaved Korean pine (Pinus koraiensis) mixed forests in Xiaoxing'an Mountains
  • Authors:GAO Meixiang, ZHU Jiyuan, NI Juanping, LI Jingke, LIN Lin and WU Donghui
  • Abstract:The term beta diversity was first introduced by Whittaker in 1960. It is described as variation of the species composition of assemblages. Beta diversity can be partitioned into two antithetic components, that is spatial species turnover and nestedness of species assemblages. Identifying those two components of beta diversity is an important task for revealing the mechanisms of community assembly. Some studies have been performed to disentangle the spatial species turnower and nestedness for communities in aboveground ecosystems, however, beta diversity of assemblages in belowground ecosystems is still unclear. The objective of this study is revealing the beta diversity of ground beetle assemblages and then partitioning the beta diversity into spatial species trunover and nestedness of species assemblages. Field experiments were carried out using pitfall traps in two broad-leaved Korean pine (Pinus koraiensis) mixed forests in Liangshui and Fenglin nature reserves, respectively, Xiaoxing'an Mountains, Northeast China. We collected ground beetles in a 9 hm2 plots (300 m×300 m) by regular sampling method in August, October in Liangshui plot. We captured ground beetles in a 9 hm2 plot (300 m×300 m) with the same method in August, October in Fenglin plot. There were 450 traps in Liangshui and Fenlin plots in total, respectively. We identified beetles into species level. We analyzed Carabidae, Staphylinidae and Silphidae beetles because their dominance in richness and abundance in each plot. We evaluated beta diversity based on PERMDISP2 method. We partitioned total beta diversity into spatial species turnover and nestedness of species assemblages. In total, 39 species and 856 individuals were captured in Liangshui plot. Forty-three species and 1182 individuals were collected in Fenglin plot. Results of diversity analysis showed that (1) Significantly higher species richness and abundance of entire beetle assemblages (total beetles of those three families) were detected in August in Liangshui plot. While significantly higher species richness and abundance of entire beetle assemblages were detected in October in Fenglin plot. The distribution of species richness and abundance for each Carabidae, Staphylinidae, Silphidae assemblages in Liangshui and Fenglin plots were family dependent. (2) There were no significant differences of beta diversities in ground beetle assemblages between Liangshui and Fenglin plots, except for Carabidae and Silphidae assemblages in August. (3) Beta diversity patterns for entire ground beetle assemblage and each family beetle assemblage were almost completely caused by spatial species turnover in Liangshui and Fenglin plots, while the contributions of nestedness of species assemblage were small. It suggested that beta diversities of ground beetle assemblages were mainly structured by spatial species replacement but not by species loss, suggesting a high proportion of endemics present in the two mixed forests. In this study, we suggested that spatial species turnover is the most important component for beta diversity in broad-leaved Korean pine mixed forest, therefore a more important role of spatial species turnover should be considered for understanding the mechanisms driving ground beetle assemblages in broad-leaved Korean pine mixed forest. This study provides scientific foundation for revealing the mechanisms of community assembly in soil animal community.
  • DownLoad:Beta diversities of ground-beetle assemblages in two broad-leaved Korean pine (Pinus koraiensis) mixed forests in Xiaoxing'an Mountains.PDF
  • Effects of woodland types with different levels of human disturbance on pollinators: A case study in Gongyi, Henan, China
  • Authors:WANG Meina, LU Xunling, CUI Yang, WANG Mengru and DING Shengyan
  • Abstract:Different types of woodlands, which provide important ecosystem services for human beings, maintain the stable development of society and have positive effects on the protection of pollinators. In recent years, the diversity of pollinators has been greatly influenced by human activities, changes in climatic variables, invasion of alien species, and changes in land use. To study the status of species diversity of pollinators and plant communities in different types of woodlands (Quercus variabilis, Paulownia fortunei,and Populus spp.), 24 sampling points were selected in field margin systems in the hilly regions of western Henan. Yellow, white, and blue traps were deployed, and a mixture of approximately 200 mL of water and 1 drop of detergent was poured into the traps to capture pollinators. These data were combined with the characteristics of local plant communities to analyze the effects of different woodland type on the diversity of pollinators. We captured 8386 individuals of six orders and 83 families, mainly belonging to Hymenoptera, Diptera, Coleoptera, Lepidoptera, Hemiptera, and Thysanoptera, with a total of six pollinator functional groups. Hymenoptera, Diptera, Coleoptera, and Lepidoptera were selected as the four kinds of main pollinators to be analyzed. Results showed that the individual number and dominance of pollinators in Populus spp. were greater than those in P. fortunei and Q. variabilis, but the diversity of pollinators in P. fortunei was greater than that in Q. variabilis and Populus spp. In terms of individual abundance of pollinators, Q. variabilis differed significantly from P. fortunei (P < 0.05)and Populus spp. (P < 0.01), whereas P. fortunei did not differ from Populus spp. Non-metric multi-dimensional scaling (NMDS) and Analysis of similarities (ANOSIM) revealed that the composition of pollinator communities in Q. variabilis differed significantly from P. fortunei and Populus spp. (P < 0.05), whereas Q. variabilis did not vary substantially from Populus spp. Among the seven environmental variables studied, according to Redundancy analysis (RDA), coverage of trees and altitude were negatively related to the diversity of pollinators (P < 0.05). Altitude was significantly correlated with the first axis (r=0.3242, P < 0.05), indicating that the first axis was characterized by an elevation gradient, with the first axis increasing from left to right, and habitats changed from lower Populus spp. to higher Q. variabilis, and pollinator insects were mainly distributed in the middle to high-altitude areas. Coverage of trees (r=-0.5061, P < 0.05) was significantly correlated with the second axis, indicating that the second axis was characterized by coverage of trees increasing from top to bottom, and the transition was from the lower cover of Q. variabilis to that of Populus spp. The pollinators changed from Hymenoptera in lower tree coverage to Coleoptera in the higher tree coverage. The interference of human activities was not completely negative to pollinators, and pollinators had a positive response under moderate disturbance. Moreover, the diversity of pollinators was closely related to the surrounding environmental variables, including seasonal variation, vegetation characteristics, temperature, humidity, and human activities. The composition of pollinator communities in different woodland types varied, and the diversity of habitats and vegetation supported more food sources and habitats for the species; therefore, for the development of pollinator communities and improvement of ecosystem services in local areas, it is important to increase the protection of different types of woodland.
  • DownLoad:Effects of woodland types with different levels of human disturbance on pollinators: A case study in Gongyi, Henan, China.PDF
  • Effects of simulated nitrogen deposition on temperate forest soil nematode communities and their metabolic footprints
  • Authors:CHENG Yunyun, SUN Tao, WANG Qingkui, LIANG Wenju and ZHANG Xiaoke
  • Abstract:Previous studies have shown that nitrogen deposition has a significant effect on the composition and diversity of soil nematode community. However, most studies focused on the effect of inorganic nitrogen, and the influences of different forms of N on soil nematode communities remained unclear. Based on the five-year simulated N-deposition experiment, we investigated the effects of N deposition on soil nematode communities. Four treatments, including the control (no nitrogen addition; CK), inorganic N (NH4NO3; IN), organic N (urea and glycine 1:1; ON), and mixed nitrogen (inorganic and organic N at the ratio of 7:3, MN), were studied. The soil nematodes were collected using the shallow basin method. The soil chemical properties, such as pH, potentiometry, soil water content (oven drying method) and elemental composition, were tested. The trophic composition, funnel analysis, and metabolic footprints were analyzed to understand the effect of different forms of N on soil nematode functional diversity. A total of 50 genera were classified. Of these 29, 37, 34, and 29 genera were included in the CK, IN, MN, and ON treatments, respectively. Rotylenchus and Macroposthonia were the dominant groups in all treatments. The results showed that IN, ON, and MN significantly increased the content of nitrate nitrogen compared with CK. The total numbers of nematodes in all treatments were not significantly different. MN significantly decreased the abundance of fungivores compared with IN, while ON increased that of omnivores-predators. Compared with CK, the IN treatment increased the diversity index (H') of soil nematodes. Furthermore, IN significantly increased the evenness index (J') compared with CK and MN. The dominance index (λ) was the highest in the MN treatment, and the nematode channel ratios in all treatments were more than 0.75, indicating that the process of soil decomposition occurs mainly through a bacterial-based energy channel. The results of the nematode funnel analysis indicated that the structure index in the CK and ON treatments was high, while the enrichment index was low, showing that the degree of interference was low and the soil food-web tended to be structured. The enrichment and structure indices of nematode communities in the ON and MN treatments were more than 50, indicating the stability of food web in the soil. The metabolic footprint and biomass carbon of fungivores were the highest in the IN treatments among all treatments. ON and MN significantly increased the metabolic footprint and biomass carbon of omnivores-predators. All results indicated that N deposition with different forms of nitrogen fertilization affected not only the composition of a soil nematode community, but also its metabolic footprints. Our findings contribute to understanding the response mechanism of temperate forests to nitrogen deposition.
  • DownLoad:Effects of simulated nitrogen deposition on temperate forest soil nematode communities and their metabolic footprints.PDF
  • Behavioral responses of breeding common coots(Fulica atra) to recreational disturbancein the Anbang River Nature Reserve
  • Authors:CHENG Kun, Ayjan Yerken, LI Feifei and ZONG Cheng
  • Abstract:Ecotourism and outdoor recreation occur in wetlands worldwide, including sea coasts and inlands, and many species of waterfowl are faced with increasing disturbance from recreational activities of human beings. Common coots (Fulica atra) are widely distributed throughout the Old World and Australia, and breed in swamps in most of northern China. This species is indicative of wetland quality because it requires large areas of open water and good cover for nesting habitat, and common coot populations decline when habitat quality is degraded. Therefore, it is important to determine the response of common coots to recreational disturbance. In this study, the diurnal activities of breeding common coots were observed in recreational and control areas in the Anbang River Nature Reserve in Heilongjiang Province from 2006 to 2007. The results indicated that:(1) during the pre-laying period, common coots in the recreational area exhibited escape behavior significantly more often than that did those in the control area (F1,18=62.364, P<0.01); (2) the behavioral responses of breeding common coots during the incubation period were more intense than during the pre-laying period. Firstly common coots exhibited escape behavior more often in the recreational area (male:F1,8=40.653, P<0.01;female F1,8=32.028, P<0.01); secondly the female common coots reduced their incubation time (F1,8=13.521, P<0.01) and continuous periods of incubation were shorter, whereas forging time decreased for male common coots and the peak time increased in recreational area relative to that observed in the control area. Our results indicated that recreational activities disrupted behavioral continuity of breeding common coots. The breeding behavior of female and male common coots and their response to human disturbance differed. Based on the responses of common coots to recreational activities, several alternatives were proposed, including increasing the amount of wetland plant cover between the human footpaths and common coot territories, and growing wetland plants adjacent to the swamp shore and near coot nests to improve habitat quality, provide escape cover, and alleviate direct disturbance by human.
  • DownLoad:Behavioral responses of breeding common coots(Fulica atra) to recreational disturbancein the Anbang River Nature Reserve.PDF
  • Habitat selection of the Blue-Crowned Laughingthrush during the breeding season
  • Authors:HUANG Huiqin, LIU Tao, SHI Jinze, LIU Peng and ZHANG Weiwei
  • Abstract:We investigated breeding groups of the Blue-crowned Laughingthrush (Garrulax courtosis) from April-July in 2013-2015 in Wuyuan, Jiangxi Province. For each breeding plaque, we measured the altitude, distance from mountain, water resource, and disturbance, we also calculated the area, perimeter, and shape index of the plaques. We set four control plaques (5km away from the breeding plaques) in the same forest type as that of the breeding plaques. Thereafter, we compared the breeding and control plaques for the factors mentioned above. The results showed that the altitude, distance from mountain, and disturbance of the breeding plaques were significantly smaller than that of the control plaques. The laughingthrush preferred to breed in low altitude, broad-leaved forests close to the mountain and village. This might be related to abundance of food and lower density of predators in these areas. At the microhabitat scale, we chose breeding site B as the study area, because it was the most stable. We measured 10 factors in the breeding area and the control area without nests of laughingthrush in the same forest. The 10 factors were analyzed with resource selection functions and selectivity coefficient of Vanderploeg and Scavia. The result of resource selection functions indicated that herb density and herb height were the main factors influencing habitat selection of the laughingthrush at microhabitat scale. However, the regression coefficient demonstrated that the laughingthrush preferred to build its nests on Celtis tetrandra,Liquidambar formosana, and Pterocarya stenoptera, with height >20m and diameter at breast height (DBH) 40-80cm, in an area with moderate-high herb coverage (60%-90%). In conclusion, these results suggested that the laughingthrush was selective for the nesting tree species, and its height and DBH. In addition, they required moderate-high herb coverage under the nesting tree. Herb density might reflect the availability of insects, which was the main food in the breeding season. This finding indicated the laughingthrush chose to nest in the area with better food abundance.
  • DownLoad:Habitat selection of the Blue-Crowned Laughingthrush during the breeding season.PDF
  • Avian and mammalian biodiversity of Heilongjiang Liangshui and Fenglin Reserve
  • Authors:BAO Xinxin and LIU Bingwan
  • Abstract:Avian and mammalian biodiversity was monitored by camera traps in Heilongjiang Liangshui Reserve from December 2013 to May 2015 and at Fenglin Reserve from April 2014 to May 2015. In Liangshui Reserve, we collected 10,736 capture dates and 14726 effective photographs, including 514 independent mammal photos and 107 independent avian photos. The mammalian fauna identified belonged to four orders, seven families and 11 species, and the avian fauna belonged to four orders, eight families, and 11 species. In Fenglin Reserve, we collected 7460 capture dates and 13677 effective photos, including 638 independent mammal photos and 166 independent avian photos. The mammalian fauna identified belonged to three orders, six families, and nine species and the avian fauna belonged to four orders, 10 families, and 16 species. The number of avian and mammalian fauna monitored accounted for 70%-78% of the total number of species in Liangshui Reserve, whereas that in Fenglin Reserve accounted for 80%-89%. A larger number of avian and mammalian fauna were monitored in Liangshui Reserve and Fenglin Reserve, respectively. Sciurus vulgaris and Eutamias sibiricus possessed the highest Relative abundance index(RAI)among the mammals, followed by Capreolus capreolu; among the avians, Sitta europaea, and Turdus pallidus possessed the highest RAI. The biodiversity index revealed no significant difference in diversity between avian and mammalian fauna. In addition, the mammal community similarity index (Cs) was 0.621, suggesting that avian and mammalian fauna of Liangshui Reserve were largely similar to those in Fenglin Reserve. The present survey suggests that we lack data on nocturnal small rodents among mammals, and most of the avian fauna monitored mainly live ower the forest.
  • DownLoad:Avian and mammalian biodiversity of Heilongjiang Liangshui and Fenglin Reserve.PDF
  • Response of physiological characteristics and anatomical structure of roots in Amorpha fruticosa seedlings exposed to simulated drought with PEG-6000
  • Authors:WANG Jinghong, ZHANG Xiumei, CHEN Ai, ZHOU Yunwei, CHEN Peng and JIANG Yuanfang
  • Abstract:In this study, we used the PEG-6000 to simulate drought stress, and determined the content of soluble sugars, soluble protein, MDA(Malondialdehyde), and free proline, and changes in enzyme activities of SOD(Superoxide dismutase) and POD(Peroxidase) in roots of Amorpha fruticosa seedlings and in their anatomical features. Our objectives were to examine the effects of different levels of drought on the physiological indices and internal anatomical structures of seedlings of Amorpha fruticosa. Furthermore, we explored the adaptability response and regulation mechanism to water stress of Amorpha fruticosa seedlings. The results indicated that MDA appeared when the concentration of PEG-6000 was more than 50g/L, and the membrane system of Amorpha fruticosa seedling roots began to suffer damage. When the PEG-6000 concentration reached 250g/L, the extent of damage was significantly enhanced, reaching 1.6 times that of the the control group, and at the beginning of osmotic adjustment (free proline content increased significantly), it reached 3.8 times that of the control group. When the concentration of PEG-6000 solution was less than 200g/L, the osmotic adjustment process was not initiated in the roots of Amorpha fruticosa seedlings with free proline. The physiological metabolism of the cell was verified through changes in soluble sugar and soluble proteincontent, and SOD and POD activity. When the concentration of PEG-6000 was 200g/L, the soluble sugar content was 0.121mg/g, reached its lowest point, and then increased. As the PEG-6000 solution concentration further increased to 250g/L, the soluble sugar content in the roots of Amorpha fruticosa seedlings rapidly increased to 0.64mg/g, which was 63.37% of that of the control group. Soluble protein content in the low concentration of PEG-6000 solution (50g/L) treatment decreased to 61.5% of that of the control group, followed by fluctuating changes. SOD and POD activities were similar to PEG-6000 simulated drought stress, and rapidly responded to PEG-6000 simulated drought stress treatment. Simultaneously, the enzyme activity of POD and SOD were increased. When the concentration of PEG-6000 was 50g/L to 100g/L, the synthesis of antioxidant enzyme was the highest, and then it decreased. SOD amplitude activity differed by more than six fold. Changes in POD activity were relatively small, and the difference in amplitude was less than a multiple of one. The 60-、day PEG-6000 solution simulating the drought stress affected the growth and development of the root system of the Amorpha fruticosa seedlings. With the increasing concentration of PEG-6000, the diameter of the vascular bundles increased. At the same time, the diameter of the catheter decreased, but its density increased. When the concentration of PEG-6000 reached 250g/L, the catheter density increased by 41.3% compared with that of the control group, and xylem thickness increased by 91.5% compared with that of the control group. The results showed that under different levels of drought stress treatments, the internal physiology and root anatomical structures of Amorpha fruticosa varied. The stress conditions of water and self-、growth and development balance needs were satisfied by altering their physiological metabolism and the internal anatomical structure of the roots.
  • DownLoad:Response of physiological characteristics and anatomical structure of roots in Amorpha fruticosa seedlings exposed to simulated drought with PEG-6000.PDF
  • Growth response of Chinese woody plant seedlings to different light intensities
  • Authors:LIU Cong, TIAN Tian, LI Shan, WANG Fang and LIANG Yu
  • Abstract:As an important environmental factor, light has a substantial effect on plant seedling growth. The amount of light changes considerably during forest successions or micro-successions in mature forests, and therefore, it is necessary to evaluate the effects of light on the growth of woody plant seedlings of different life forms. Although much recent research has been conducted to determine shade tolerance of woody plants, most of these studies focused only on one or two plant species, and review studies across experiments are needed to elucidate plant responses to light conditions. In this meta-analysis, we collected data from experimental studies on growth responses of woody plants to shading gradients. Consequently, 106 species belonging to 42 families from 71 published papers (to 2016) were collected. Extracting data from these studies, we conducted a meta-analysis by using MetaWin 2.1 software. The growth responses of woody plant seedlings were analyzed using the mean values of seedling height, basal diameter, biomass, and height:basal area ratio in the treatments relative to those of the control (with full light) to estimate the appropriate effect size for the analysis. Our results showed that (1) Compared with seedling height, basal diameter of plant seedlings was more sensitive to shade treatments, resulting in higher height:basal area ratio for seedlings growing under shade treatments; (2) Shrub seedlings exhibited stronger tolerance to shade treatments than did tree seedlings; (3) Regarding life forms with different leaf traits, basal diameters of deciduous broadleaved and evergreen broadleaved species were significantly inhibited by shading of 0-20% and 20%-40% light intensity of unshading control, whereas the basal diameter of evergreen conifers was relatively insensitive to shade treatments; (4) The height:basal area ratios of deciduous broadleaved and evergreen broadleaved plants were significantly enhanced by shading treatments, whereas the height:basal area ratio of evergreen conifers were relatively insensitive to shading treatments, which indicated that light responses of plant seedlings may strongly depend on the leaf traits of the species. Our results increased our understanding of how seedling growth responds to different light conditions in natural forests.
  • DownLoad:Growth response of Chinese woody plant seedlings to different light intensities.PDF
  • Effects of rhizosphere aeration on photosynthesis and ion absorption in cotton seedlings under salt stress
  • Authors:HUANG Qingrong, QI Lin and BAI Xinfu
  • Abstract:In this study, the effects of rhizosphere aeration on leaf photosynthesis and root ion absorption in hydroponically cultivated cotton seedlings under salt stress were investigated in terms of the changes in the leaf gas exchange parameters, chlorophyll fluorescence parameters, and Na+ and K+ contents. The results showed that net photosynthetic rates decreased under salt stress and hypoxia. In the early stages of stresses, salt stress caused a more severe effect on leaf photosynthesis than oxygen deficiency. In contrast, insufficient oxygen negatively affected leaf photosynthesis in the late stages of stress than salt stress. Under mild salt stress, the additional hypoxia stress resulted in a decrease in the net photosynthetic rate, mainly due to the stomatal factor (insufficient carbon dioxide resulting from stomata closure or contraction) rather than the effect of the photosynthetic apparatus. Non-stomatal factors (injury to the photosynthetic system) gradually lowered the net photosynthetic rate with intensified salt and prolonged hypoxia stresses. The net photosynthetic rates and maximum quantum efficiency of photosystem Ⅱ in cotton leaves under rhizosphere aeration were significantly higher than those in cotton leaves without rhizosphere aeration under the same salt stress. It was suggested that oxygen deficiency in the root environment worsened the adverse effect of salt stress on photosynthesis. Ion accumulation in different organs of cotton seedlings indicated that salt stress reduced the capability of K+ absorption, Na+ exclusion, and the selective transportation of K+, thus decreasing K+ content and increasing Na+ content and the [Na+]/[K+] ratio both in roots and leaves. However, rhizosphere aeration could significantly improve the above conditions induced by salt stress, and reduce the[Na+]/[K+] ratio. Moreover, K+ and Na+ contents in roots were more influenced by salt stress, whereas K+ and Na+ contents in leaves were more affected by rhizosphere aeration. In conclusion, salt stress and oxygen deficiency around roots can lead to the decline in the net photosynthetic rate, injury of photosynthetic apparatus, and a disorder in the ion balance in cotton seedlings. On the other hand, rhizosphere aeration could alleviate the adverse effects of salt stresses on photosynthesis, increase the selective absorption and accumulation of K+ in roots and leaves, thereby reducing the ratio of [Na+]/[K+], and improving the adaptability and resistance of cotton seedling to salt stress.
  • DownLoad:Effects of rhizosphere aeration on photosynthesis and ion absorption in cotton seedlings under salt stress.PDF
  • Spatial distribution patterns and associations of tree species in typical natural secondary forest communities in Zhejiang Province
  • Authors:WU Chuping, YUAN Weigao, SHENG Weixing, HUAN Yujie, CHEN Qingbiao, SHEN Aihua, ZHU Jinru and JIANG Bo
  • Abstract:Mixed broadleaf-conifer forests and broadleaf forests are the main forest type in subtropical region. Understanding the spatial distribution of dominant tree species among these forest types can provide insights for effective forest management measures and the mechanisms of community assembly in subtropical forests. In this study, we examined the distributions and associations of dominant species with different life stages in mixed broadleaf-conifer forests and broadleaf forests separately. We established four 1 hm2 forest plots, including two in mixed forest (plots 1 and 2) and two in broadleaf forests (plot 3 and 4), to detect species associations and distributions. All trees with diameter at breast height (DBH) ≥ 5 cm were mapped and identified. For mixed-forest plots, the density of Pinus massoniana was lower in plot 1 than in plot 2. We applied spatial point pattern analysis in this study, and the spatial distribution of dominant tree species and associations of different species were analyzed. The results showed that (I) When using a complete spatial randomness null model, most populations in plot 1 showed aggregated distribution at smaller scales (<10 m) and random distributions at larger scales. However, in plots 2-4, most populations showed an aggregated distribution at all scales. In addition, when using a heterogeneous poisson null model, most populations in all plots showed random distributions at all scales; (Ⅱ) Small trees (5.0 cm < DBH < 10.0 cm) of Cyclobalanopsis glauca and Castanopsis sclerophylla showed aggregated distribution in all plots, whereas large trees (DBH > 10.0 cm) showed random distribution in plot 1 and 2 and aggregated distribution in plot 3 and 4; (Ⅲ) P. massoniana was negatively associated with other species at smaller scales in plot 1, and at all scales in plot 2. C. glauca was negativelyassociated with other species at smaller scales in plot 3, and at all scales in plot 4. All species showed negative associations at all scales. In conclusion, the spatial distribution and associations of tree species showed different patterns in the two forest types. These results indicated that the spatial distributions and associations of trees were regulated by dispersal limitation and environmental heterogeneity in mixed forest and evergreen broadleaf forest. Moreover, density dependence played an important role in mixed forests and the effects of density dependence tended to decrease along the life stages of trees.
  • DownLoad:Spatial distribution patterns and associations of tree species in typical natural secondary forest communities in Zhejiang Province.PDF
  • Characteristics of the forest deadwood carbon pool in Guangdong Province
  • Authors:ZHAO Jiacheng and LI Haikui
  • Abstract:We used compatible tree biomass equations for each component grouped by species and decay classes, and carbon fractions of above-ground and below-ground parts, based on the 8th Chinese National Forest Inventory (CNFI) data in Guangdong Province and the deadwood investigation data from typical sampling in 2016, to estimate the dynamics of the forest deadwood carbon pool in Guangdong Province, including the effects of deadwood type, stand type, and age groups. Furthermore, the contribution of stand growth characteristics and natural disasters to the deadwood carbon pool were quantified. The results showed that the carbon storage of the deadwood pool of arbor forests in Guangdong Province increased 5811.86 Pg from 2007 to 2012, which accounted for 2.94% of biomass carbon in arbor forests during the same period. Logs contributed more carbon to deadwood pool than snags. Broad-leaved mixed forests and Pinus massoniana contributed approximately 70% to the deadwood carbon pool. Within the same forest type, the deadwood carbon storage of Pinus massoniana, light hardwoods, Pinus elliottii, broad-leaved mixed forests, and hardwoods accounted for a larger proportion (>4%) of standing carbon stock, whereas Eucalyptus and Cunninghamia lanceolata accounted for a lower proportion (<1%). With respect to age groups, middle-aged stands accounted for the largest proportion of the increased carbon, whereas over-mature stands accounted for the smallest. Comparing the existing biomass carbon storage within the same age group revealed an upward trend from 2.03% for the young-aged to 4.56% for the over-mature stands. The increased carbon density was (0.7612 ±3.3988) Mg/hm2 in the province. Death owing to competition or old age was very common in the stand, and was observed in approximately 60% of the stands with deadwoods, but contributed to less than 1/4 of the increased deadwood carbon. Rather, natural disasters, which only happened in approximately 10% of the stand, contributed more than 40% to the increased deadwood carbon. The increased deadwood carbon from 2007 to 2012 declined until 2016 by approximately 85% to 785.57 Pg. The degree of decay of logs was greater than for snags. The degree of decay varied among different species and was lowest for Cunninghamia lanceolata. Human disturbance, such as over-cleaning, and decay of trees could be the main reasons for the reduced carbon storage.
  • DownLoad:Characteristics of the forest deadwood carbon pool in Guangdong Province.PDF
  • Effective precipitation and water requirements of crops in Hebei Province over 60 years
  • Authors:CAO Yongqiang, ZHU Mingming and LI Weijia
  • Abstract:Effective precipitation and water requirements throughout a growing period are important for planning irrigation and optimal water resource allocation. In this study, Jize County of Hebei Province was selected as a typical region to calculate the winter wheat, summer maize, and cotton effective precipitation and water requirements, using the Penman-Monteith equation recommended by FAO and the piecewise single value average crop coefficient method. Using the Mann-Kendall test method, we analyzed the trends of changes in effective precipitation and crop water requirements over the 1955-2015 in Jize County. The water requirement of the main crops showed a significant decreasing trend, and the average water requirement of the crops in was in the order of cotton, winter wheat, and summer maize. The maximum water requirement of winter wheat was 593.2 mm in 1968, the maximum water requirement of summer maize was 581.6 mm in 1968, and the maximum water requirement of cotton was 710.4 mm in 1972. An obvious change in water requirements, which was directly related to the improvement of crop varieties, appeared in the 1980s. The different water requirements of crops are related to the physiological characteristics of the crops. The maximum water requirements of winter wheat, summer corn, and cotton were during different growth stages; these were the middle growth stage, initial growth stage, and rapid development stage, respectively. Effective precipitation showed no significant decreasing trend in any of the three crops. The daily precipitation required for crop growth gradually declined over time, and the average effective precipitation of the crops in was in the ascending order of cotton, summer maize, and winter wheat. The maximum effective precipitation of winter wheat was 170.4 mm in 1963, the maximum effective precipitation of summer maize was 320.5 mm in 1961, and the maximum effective precipitation of cotton was 422.7 mm in 1973. Because the winter wheat growth period is concentrated in the winter and precipitation is low in this season, the effective rainfall is far lower than that for the summer maize and cotton. All three crops experienced their maximum effective rainfall mid-season. Water deficits showed a decreasing trend for all three crops, and the average effective precipitation of the crops in was in the order of winter wheat, summer maize, and cotton. There was a change in water deficits over the 60-year period included in this study The moisture loss index of winter wheat fluctuated in the range of -100 to -60 and the moisture loss index of summer maize and cotton fluctuated in the range of -80 to -20. Although the maximum water requirement and effective rainfall appeared at the same growth stage in winter wheat, the moisture loss index is relatively low during that stage, leading to a higher level of drought, so the winter wheat water shortage situation is more serious. It should be noted that the water requirement of the three crops is similar to that of water demand.
  • DownLoad:Effective precipitation and water requirements of crops in Hebei Province over 60 years.PDF
  • Spatial distribution pattern of plant community and habitat impact analysis of the drawdown zone of Pengxi River in the Three Gorges Reservoir
  • Authors:TONG Xiaoxiao, CHEN Chundi, WU Shengjun, JIA Zhenyi, YI Xuemei and MA Maohua
  • Abstract:Riparian vegetation has important ecological functions in protecting the water quality, stabilizing the bank and maintaining the habitats connectivity. The impoundment of the Three Gorges Reservoir has destroyed the original riparian vegetation and potentially threatens the reservoir ecosystem's health and stability in the Three Gorges Reservoir. This research study explored the riparian vegetation community of the newly formed drawdown zone of the Three Gorges Reservoir and the relationship between the spatial distribution patterns of plant community and the habitat influences. A field survey was carried out from August to September 2015, and 93 plant quadrats were investigated. At the same time, 14 factors including three topographic (slope, exposure, and elevation), three hydrology (flooding time, frequency, and depth), seven soil (pH, moisture content, organic matter, available nitrogen, phosphorus, and potassium, and slow-release potassium) and one historical land use (historical land use) factor were measured. These habitat factors were classified into four groups:topographic, hydrology, soil, and historical land use factor groups. The community types were identified using a two way indicator species analysis (TWINSPAN). Additionally, the effects of the four habitat factor groups and their interaction on the total variation of drawdown vegetation were partitioned using variance decomposition. The effects of 14 habitat factors on the drawdown plant communities were analyzed using the canonical correspondence analysis (CCA). The main results were as follows. (1) The drawdown plant communities were classified into five types, which were a Cynodon dactylon plus Paspalum thunbergii, Setaria viridis plus Cynodon dactylon, Vitex negundo, Imperata cylindrica plus Bidens pilosa, and Carex tristachya communities. (2) The results of the CCA indicated that drawdown vegetation and habitat factors had a significant correlation. The cumulative interpretation of the first ordination axis on vegetation spatial variation was 6.83%, accounting for 44.73% of the total interpretation of the habitat. Five types of plant communities were distributed along the first ordination axis following the altitude gradient. (3) The results of the variance decomposition showed that the soil factors group had only a 10.1% contribution. It played a major role in the spatial distribution of the drawdown plant community among the four habitat factor groups. There was a significant interaction between the four habitat factor groups. The CCA also showed that the habitat factors of flooding time, elevation, and soil moisture content played a dominant role in the spatial distribution of the drawdown plant community and their contribution were 5.3%, 3.0%, and 2.9% respectively. (4) Our results demonstrated that the explanatory power of all four habitat factor groups was low (14.6%). This may be because the drawdown zone is a newly established, complex ecotone, where habitats and landscapes are highly heterogeneous. The unexplained portion may come from the influence of anthropogenic activity, various disturbances, and large-scale landscape context.
  • DownLoad:Spatial distribution pattern of plant community and habitat impact analysis of the drawdown zone of Pengxi River in the Three Gorges Reservoir.PDF
  • Temporal and spatial characteristics of spontaneous plant composition and diversity in a Beijing urban park
  • Authors:LI Xiaopeng, DONG Li, GUAN Junhong, ZHAO Fan and WU Sijia
  • Abstract:The planted vegetation in urban green spaces results in high consumption of resources and landscape homogeneity. With the increasing ecological awareness, spontaneous plants have gained attention at home and abroad for their variety of positive attributes, including self-reproduction, low-maintenance, and ecological benefits; however, previous studies have primarily used the city environment as the study area. The distribution of spontaneous plants in urban green spaces has rarely been reported. To determine the diversity, as well as the temporal and spatial patterns of spontaneous plants in urban green spaces, we used the Beijing Olympic Forest Park as the study area for this research project. A total of 123 sample sites were selected using a 200 m grid placed over the park. Each site was a 20 m×20 m square, and all sample sites were surveyed seven times during the growing season from March to November, 2015. Combined with diversity, community cluster calculation, and Duncan tests, we analyzed the composition features, diversity, and community classification of spontaneous plants in this urban park. A total of 128 plant species were recorded, which belonged to 98 genera and 32 families. Among them, native plants accounted for 76.56% and alien species accounted for 23.44%, meanwhile, invasive species accounted for 12.50%. The species number of spontaneous plants exhibited a pattern with a single peak during the year, and the peak occurred in late August with 98 species. The number of species in the family Compositae was significantly higher than that in other families, and the percentage of foreign species increased in summer. The habitat of roadside and woodland contained the highest number of sample sites as well as more spontaneous species, 109 and 106, respectively. Community diversity was significantly higher in early October, followed by late August, late April, and early June. Community diversity among different habitats was not stable because of the varying degrees of external interference in different seasons. All communities were classified into 42 community groups based on species dominance. Each season and habitat had its own dominant species and communities, and nine community groups occurred in all the three seasons. With the variation among seasons, most groups presented a rich and colorful effect together with that of wildness. The results of this research will provide a reference for the future construction of sustainable urban vegetation with low maintenance, high biodiversity, and regional characteristics.
  • DownLoad:Temporal and spatial characteristics of spontaneous plant composition and diversity in a Beijing urban park.PDF
  • Temporal dynamics and vertical variations in the temperature sensitivity of woody-tissue CO2 efflux for typical tree species in Beijing
  • Authors:HAN Fengsen, WANG Xiaolin and HU Dan
  • Abstract:CO2 efflux (ECO2) from stems and branches is important in the regulation of biomass productivity and maintenance of carbon balance in terrestrial ecosystems. ECO2 is a temperature-sensitive physiological process. An increase in temperature could promote the activities of enzymes, decrease the gas solubility, and improve the diffusion coefficient of CO2. Until recently, great uncertainties relevant to the variations in ECO2 and their temperature-sensitivity (expressed in terms of Q10) remain poorly assessed because of the lack of continuous sampling, both in time series and space sequence. Understanding the effect of temperature on ECO2 at different time scales is important to accurately upscale the chamber-based CO2 measurements to the whole-stem. To investigate the temporal dynamics and vertical variations in woody-tissue ECO2 and their temperature sensitivity, the hourly ECO2 at four different heights (10, 130, 240, and 370 cm) of the four typical tree species (Sophora japonica, Salix matsudana, Larix principis-rupprechtii, and Platycladus orientalis) was observed using an Li-8100 automatic instrument (LI-Cor, Inc, NE, USA) on two consecutive days per month throughout 2014 in an artificial mixed forest plantation near Beijing. Simultaneously, the meteorological conditions (air temperature, relative humidity, and woody-tissue temperature) and stem radial increment were monitored using the HOBO Pro V2 probes (Onset Computer Corporation, Bourne, MA, USA) and dendrometer (CR10X, Campbell Scientific, Logan, UT, USA), respectively. The results indicated that:(1) the ECO2 of the four tree species showed similar seasonal variations, characterized by a significantly higher ECO2 in the growing months than in the dormant months. Together, the woody-tissue temperature (TW) and stem radial diameter increment (Di) of the trees explained the seasonal variation of ECO2; (2) Our study showed that the temperature-sensitivity coefficient, Q10, was not a constant, as assumed in some models, but was instead highly dependent on the measurement temperature. A lower Q10 was observed in the summer months, but a higher value was observed in the dormant months. A strong vertical variation in Q10 was observed during the growing season, showing a gradient increment with height along the trunk, and the vertical variation disappeared in the dormant months; (3) Based on the strength of correlations between stem (TW) and air temperature (TA), the daytime was divided into four periods. In growing months, the night-time temperature-sensitivity coefficient Q10 was significantly higher than that of day-time values, especially for the two deciduous species (Sophora japonica and Salix matsudana). This result implies that ECO2 is more sensitive to temperature in the night than in the daytime, and the temperature responses of ECO2 estimated by only daytime measurement can lead to the underestimated stem respiration, especially considering that the temperature increase is faster during the night-time. In contrast, the diurnal asymmetry of Q10 disappeared in the dormant months, i.e., no significant difference was observed between each of the four periods. The quantitative analysis of the temporal dynamics and vertical variations of ECO2, as well as what factors are driving these changes, would help us to improve our knowledge of the ECO2 processes and understand how climatic changes affect forest carbon budgets.
  • DownLoad:Temporal dynamics and vertical variations in the temperature sensitivity of woody-tissue CO2 efflux for typical tree species in Beijing.PDF
  • Effects of different salinity levels on the growth and physiological characteristics of roots of Tamarix chinensis cuttings
  • Authors:SONG Xiangjing, LI Shengnan, GUO Jia, YU Yilei, LIU Zhiwei and WEI Wei
  • Abstract:Tamarix chinensis is a dominant shrub in the Yellow River Delta region. Salt glands occur on the leaves of T. chinensis, which can effectively exclude salt from the plant. However, due to the effects of global climate change and human over-exploitation of seawater resources, soil salinization and degradation has occurred in this region. The growth of T. chinensis has gradually decreased under conditions of high soil osmotic pressure, poor aeration and moisture, low nutrient availability, and high soil salinity. However, the roots can directly sense soil salinity changes, which mean that the effect of differing salinity on the eco-physiological characteristics of roots of T. chinensis cuttings is very important for the ecological restoration of coastal wetlands. In the present study, we studied the effects of different salinities (0.0, 0.4%, 0.8%, 1.2%, 2.4%, 3.6% NaCl solutions) on the eco-physiological characteristics of roots of 1-year old T. chinensis. To explore the response of T. chinensis root growth and eco-physiological characteristics to different salinity levels, the rooting rate of T. chinensis cuttings, root lifespan, root number, root length, aboveground biomass, root biomass, hydrogen peroxide enzyme (CAT) activity, adenosine triphosphate (ATP) synthase, and the content of abscisic acid were determined. The results revealed that (1) the rooting rate was approximately 83% in the 0.8% NaCl treatment, and the rooting rate and life of the root decreased significantly when the salinity increased to greater than 0.8%; (2) the root length gradually decreased with increasing salinity, while the root quantity initially increased and then decreased with increasing salinity once the salinity was greater than 1.2%; (3) examining the biomass allocation pattern of T. chinensis adjustment to acclimate to salinity conditions, the aboveground biomass was higher than root biomass at lower salinity and the proportion of root biomass increased gradually; however, was still less than the aboveground biomass; and (4) the activity of ATP synthase and CAT increased when salinity was less than 0.8%, and the activities decreased when the salt content was greater than 0.8%. In addition, the content of abscisic acid increased with increasing salinity and then decreased when the salinity increased to greater than 1.2%.
  • DownLoad:Effects of different salinity levels on the growth and physiological characteristics of roots of Tamarix chinensis cuttings.PDF
  • Effects of nitrogen and phosphorus additions on soil organic carbon and nitrogen mineralization and hydrolase kinetics in Chinese fir plantations
  • Authors:NIE Erqi, ZHANG Xinyu, ZHENG Guodi, YANG Yang, WANG Huimin, CHEN Fusheng and SUN Xiaomin
  • Abstract:A long-term field experiment of nitrogen (N) and phosphorus (P) additions was established in Chinese fir plantations in subtropical China. Four treatments, i.e. control (CK), N (50kg N hm-2 a-1), P (50kg P hm-2 a-1), and NP (50kg N hm-2 a-1+ 50kg P hm-2 a-1),were selected in this study. We studied the effects of N and P additions on the soil mineralization rate of carbon (Cmin) and nitrogen (Nmin) and the kinetics of β-glucosidase(βG)and N-acetyl-glucosaminidase(NAG). The results showed that (1) N additions had negative effects on Cmin and Nmin, which were lower by 25% and 18%, respectively, compared to CK. (2) P (P, NP) additions decreased the Vmax and Km of NAG by 26%-60% compared to CK, whereas NP combined additions greatly enhanced the catalytic efficiency (Vmax/Km) of βG and NAG (P<0.05). (3) Cmin was positively correlated with dissolved organic carbon (DOC) contents, whereasNmin was positively correlated with pH and negatively correlated with NH4+-N and NO3--N contents. The catalytic efficiencies of βG and NAG were negatively correlated with NH4+-N and NO3--N contents (P<0.05). The Km of βG and NAG was positively correlated with NH4+-N and NO3--N (P<0.05), The Vmax of βG was positively correlated with NH4+-N and NO3--N (P<0.05), and the Vmax of NAG was negatively correlated with soil organic carbon, total nitrogen, total phosphorus, and available contents (P<0.05). Our results suggest that N additions had negative effects on Cmin and Nmin by decreasing soil pH, increasing soil available N contents, and inhibiting the Vmax/Km of βG and NAG, whereas NP additions increased soil available P and the Vmax/Km of βG and NAG in southern subtropical Chinese fir plantations.
  • DownLoad:Effects of nitrogen and phosphorus additions on soil organic carbon and nitrogen mineralization and hydrolase kinetics in Chinese fir plantations.PDF
  • Output mechanism of soil nutrients from karst slope farmland under simulated rainfall
  • Authors:PENG Xudong, DAI Quanhou and LI Changlan
  • Abstract:Soil water and nutrient loss are not only the main reasons for degradation of land quality and declines in productivity, but also important factors contributing to the pollution of underground water in karst regions. Compared with non-karst areas, the special structure of karst slopes requires a different theory regarding soil nutrient loss. Previous studies have determined that rainfall is the primary external factor resulting in soil water and nutrient loss on slopes. Hence, determination of the mechanism of soil erosion and nutrient loss will allow for the elucidation of output characteristics of soil nutrients from karst slope farmlands under different rainfall intensities. In addition, understanding the direction and vehicle of nutrient loss could clarify the method of soil nutrient transfer on karst slopes. However, it is difficult to directly observe underground runoff and sediment on karst slopes (i.e., there is no feasible research method). Using karst slope farmlands as an example, the surface micro-topography and structural characteristics of underground pores and fissures were simulated in a laboratory based on field investigations on slope farmlands in the Guizhou Province karst areas. The goal of this study was to determine the characteristics of nitrogen, phosphorus, and potassium loss in runoff, as well as the sediment yield from surface and underground in karst slope farmlands under different rainfall intensities using simulated rainfall experiments. The results indicated that:1) For light (50mm/h) and moderate rainfall intensity (70mm/h), runoff on karst slopes was primarily dominated by underground runoff; for heavy rainfall intensity (90mm/h), both surface and underground runoff were nearly equal, with the surface water runoff being slightly higher than that of underground runoff. Sediment yield changed from equivalent surface and underground sediment under the light rainfall intensity to surface sediment production being dominant at greater rainfall intensities. 2) The concentration of each nutrient in runoff exhibited an initial scouring effect during the process of rainfall erosion on karst slope farmlands. Influenced by the effect of soil absorption, the effect of rainfall intensity on total potassium (TK) and total nitrogen (TN) concentration in runoff was substantially greater than that of total phosphorus (TP). 3) The output load for each nutrient in surface runoff, surface sediment, and total sediment increased with increasing rainfall intensity. The output load of TK was dominated by sediment, but those of TN and TP were dominated by runoff on karst slope farmlands. With respect to runoff output, the output load of both TN and TP were dominated by underground runoff. The percentage of the TP load in the surface runoff relative to total runoff ranged from 11.6% to 46.2% and that of TN ranged from 7.0% to 48.5%; however, the output load of TK was equal between the surface and underground water, with the percentage of surface runoff relative to total runoff ranging from 43.5% to 57.0%. The sediment load for all nutrients was dominated by surface sediment, and the percentage of each nutrient in the surface sediment relative to total sediment was more than 54.5%. These results could provide basic parameters and a scientific basis to initiate control for soil water and nutrients loss on karst slope farmlands.
  • DownLoad:Output mechanism of soil nutrients from karst slope farmland under simulated rainfall.PDF
  • Effects of elevation and tourism disturbance on meadow soil infiltration on Wugong Mountain
  • Authors:LI Zhi, YUAN Yingdan, HU Yaowen, MENG Wenwu, ZHANG Xueling, GUO Xiaomin, ZHANG Wenyuan, HU Dongnan and NIU Dekui
  • Abstract:Soil infiltration capacity is one of the most important factors affecting soil erosion and is an important index reflecting soil water conservation and regulation function. The Wugong Mountain meadow is a representative subtropical mountain meadow in Jiangxi Province, which is in the typical and special vertical vegetation zone of East China. However, human disturbance and excessive tourism development caused serious degradation and fragmentation of this fragile mountain meadow. This study evaluated the alpine meadow soil infiltration capacity at different elevations and disturbance levels from the fringe meadow upwards to the top in Wugong Mountains. Set an elevation gradient experiment treatment at intervals of about 100 m, four experiment treatments namely 1600 m, 1700 m, 1800 m, and 1900 m. In addition, according to the loss of vegetation coverage caused by tourism disturbance, set four disturbance experiment treatments which included the no disturbance (control check, abbreviation was CK, vegetation coverage rate ≥ 90%), light disturbance (LD, 60% ≤ vegetation coverage rate < 90%), medium disturbance (MD, 30% ≤ vegetation coverage rate < 60%), and severe disturbance (SD, vegetation coverage rate <30%). Various indices including the soil initial infiltration rate, steady infiltration rate, average infiltration rate, total infiltration of the first 60 min, soil temperature, soil humidity, soil bulk density, maximum water holding capacity, minimum water holding capacity, capillary water holding capacity, pH, organic matter, available nitrogen, available phosphorus, and available potassium were measured in two soil layers, 0-20 cm and 20-40 cm, to analyze soil infiltration characteristics at different elevations and disturbance levels and to be able to discuss the factors that affect the soil infiltration and provide references for the ecological restoration and sustainable management of degraded meadows in the subtropical zone. The results showed that (1) as elevation increased, soil infiltration decreased at elevations in the 1600-1800 m range, but increased at 1900 m. The amount of soil infiltration from highest to lowest was 1600 m > 1700 m > 1900 m > 1800 m. (2) As disturbance level increased, soil infiltration decreased, and the amount of soil infiltration from highest to lowest was CK > LD > MD > SD. (3) Soil infiltration of the upper layer (0-20 cm) was higher than that of the lower layer (20-40 cm), and infiltration rate from highest to lowest was initial infiltration rate > average infiltration rate > steady infiltration rate. (4) The common empirical infiltration model was the most suitable representation of the infiltration process of meadow soil moisture in the Wugong Mountains, followed by the Horton model, whereas the Philip and Kostiakov models were not suitable. (5) Soil infiltration and capillary water-holding capacity were significantly positively correlated (P < 0.05), and was significantly negatively correlated with soil bulk density (P < 0.05). Available nitrogen content was significantly positively correlated with initial infiltration rate and average infiltration rate (P < 0.05), and available potassium content was significantly positively correlated with the steady infiltration rate, average infiltration rate, and with total infiltration (P < 0.05).
  • DownLoad:Effects of elevation and tourism disturbance on meadow soil infiltration on Wugong Mountain.PDF
  • Effect of Kudzu coverage on soil moisture and temperature in the gully bank of the Dry-hot Valley Region
  • Authors:XIAO Liang, XIONG Donghong, ZHANG Baojun, ZHANG Su, WU Han, YANG Dan, LI Jiancha and SHI Liangtao
  • Abstract:Soil moisture and temperature change sharply in the gully bank of the Dry-hot Valley Region, and vegetation restoration is extremely difficult in this area. Based on field investigation and in situobservation in the gully bank under the coverage of Kudzu, we set four treatments depending on the biomass of Kudzu cover (T1:309.70g/m2 fresh Kudzu; T2, T3, and T4:594.34, 1103.43, and 1693.27g/m2 withered Kudzu, respectively), and used plots without Kudzu coverage as control. The effect of the different extents of Kudzu coverage on soil moisture and temperature in the gully bank were studied in situ. The results showed that (1) soil water content in the gully bank under fresh coverage of Kudzu (T1) was 8.68%, which was 4.47% lower than that in the bare gully bank. However, soil water content in areas under withered Kudzu coverage (i.e., T2, T3, and T4) was 14.91%, 16.75%, 19.44%, respectively, which were greater than that in the bare gully bank by 1.76%, 3.60%, 6.29%, respectively. (2) Fresh coverage of Kudzu resulted in larger active layer, range ability, and variation degree than those in the bare gully bank, whereas withered coverage of Kudzu revealed the opposite trend. (3) In the soil moisture-supplying period, the soil moisture increased with increase in Kudzu biomass. However, the rate of soil moisture loss decreased with increase in Kudzu biomass during this period. Furthermore, with increase in biomass of withered Kudzu, the rate of soil moisture waveform reduced, fluctuation decreased, and wavelength increased. (4) With increase in the biomass of Kudzu, soil temperature fluctuation in the surface layer of the gully bank decreased. Our findings have potential applications in vegetation restoration and habitat improvement of the gully bank.
  • DownLoad:Effect of Kudzu coverage on soil moisture and temperature in the gully bank of the Dry-hot Valley Region.PDF
  • Effects of simulated acid rain on soil labile organic carbon and carbon management index in subtropical forests of China
  • Authors:ZHANG Huiling, WU Jianping, XIONG Xin, CHU Guowei, ZHOU Guoyi and ZHANG Deqiang
  • Abstract:Four gradients of simulated acid rain treatment[pH 3.0, 3.5, 4.0 and CK (lake water)] were designed to determine the effects of simulated rain on soil carbon stabilization and the carbon management index (CMI) in three subtropical forests at different successional stages. The stages are, a young pine forest (PF), a transitional mixed conifer and broadleaf forest (MF), and an old grow-growth broadleaved forest (BF) at the Dinghushan Nature Reserve. The soil organic carbon (SOC), readily oxidation organic carbon (ROC), particulate organic carbon (POC), microbial biomass carbon (MBC), dissolved organic carbon (DOC), and soil properties were analyzed. The results showed that the SOC, ROC, and POC contents increased with acid treatment. However, simulated acid rain restrained the activity of microorganism while the SMBC content showed the opposite trend. The analysis showed that ROC333 and POC with SOC had highly significant correlations, with correlation coefficients of 0.853 and 0.846 respectively. Our results also indicated a significant correlation between other labile fractions and the SOC. The value of L and LI decreased with the progressive succession of forests while the rangeability of L and LI showed the same trend. It's indicated the proportion of labile portion to non-labile portion decreased. The results also showed CPI and CMI increased with the progressive succession of forests and, thus, the BF soil pool was more stable. That's due to BF soil has higher C sequestration and lower lability than MF and PF forests, so the carbon is easily to sequestrate and more stable if the carbon lability index decreased. Moreover, the LI was more sensitive than the carbon cool index (CPI) was. From the variation of indicators of the three forests, we can conclude that the response sensitivity of acid rain showed an increasing trend with the progressive succession of forests. All the parameters investigated showed the following order of decreasing sensitivity:CMI > R333 > POC > SMBC > R167 > R33 > LI > DOC > CPI > SOC.
  • DownLoad:Effects of simulated acid rain on soil labile organic carbon and carbon management index in subtropical forests of China.PDF
  • Emission fluxes of CO2, CH4, and N2O from artificial and natural reed wetlands in Bosten Lake, China
  • Authors:WANG Jinlong, LI Yanhong and LI Fadong
  • Abstract:CO2, CH4, and N2O, have strong warming potentials and are considered to be the primary greenhouse gases in the atmosphere. Global warming caused by the increasing concentrations of atmospheric CO2, CH4, and N2O is one of the hotspots in global change field. Greenhouse gas (GHG) fluxes in reed wetlands are critical in evaluating the source/sink strength of GHG in arid area. We studied the dynamics of soil CO2, CH4, and N2O fluxes using static chamber-based on gas chromatography in two reed wetlands of the freshwater Bosten Lake, located in an arid area of Northwestern China. During a full year of monitoring, environmental variables (including soil moisture, soil temperature, air temperature, pH and salinity) were measured to determine the effects of abiotic factors on soil CO2, CH4, and N2O fluxes in artificial and natural reed wetlands. SPSS 19.0 for Windows was used to analyze the relationships between environmental factors and soil CO2, CH4, and N2O fluxes. The results showed that soil CO2, CH4, and N2O fluxes in the artificial reed wetland were 10.1-588.4mg m-2 h-1, 1.32-29.7μg m-2 h-1 and 3.1-64.8μg m-2 h-1, respectively, which was comparable with the values from the natural reed wetland. Higher soil CO2 emissions occurred in summer, whereas CH4 and N2O emissions mainly occurred in late spring and early summer. Temperature was the main factor controlling soil CO2 and N2O fluxes in both reed wetlands (P < 0.01). Soil CH4 emission flux was affected by both temperature and moisture. According to regression analysis, the combination of near-surface temperature, top 5cm soil temperature, and soil water content could explain 71% and 74.5% of soil CH4 flux in artificial and natural reed wetlands, respectively. Soil organic carbon, pH, salinity, NH4+-N, and NO3--N are also influencing factors of CO2, CH4, and N2O fluxes in artificial and natural reed wetlands. However, the differences in CO2, CH4, and N2O emissions from soils of artificial and natural reed wetlands were caused by differences in soil organic carbon, soluble nitrogen, and biomass. Based on the centennial scale, the soils of artificial and natural reed wetland were "sources" of GHG, and the global warming potential from artificial reed wetland was higher than that from natural reed wetland.
  • DownLoad:Emission fluxes of CO2, CH4, and N2O from artificial and natural reed wetlands in Bosten Lake, China.PDF
  • The effects of biological soil crust succession on soil ecological stoichiometry characteristics
  • Authors:GAO Liqian, ZHAO Yunge, XU Mingxiang, SUN Hui and YANG Qiaoyun
  • Abstract:Biological soil crusts (biocrusts) are ubiquitous living surface covers in arid and semi-arid regions. The succession of biocrusts exerts significant influence on soil nutrient cycles owing to their functions of carbon and nitrogen fixation. Therefore, soil ecological stoichiometry characteristics are likely to be affected by the succession of biocrusts. To explore the effects of biocrusts on the contents of organic carbon (C), total nitrogen (N), total phosphorus (P), and their stoichiometric characteristics, biocrusts in six successional stages, totaling 59 sites, were chosen from the hilly Loess Plateau region. Biocrusts and subsoils (0-2 cm, 2-5 cm, and 5-10 cm) were sampled at each site. The contents of C, N, and P were analyzed and their ratios were calculated. The results showed that biocrusts significantly affected the contents of C, N, and P, and their ratios, which resulted in differences between biocrusts and the soils beneath them. Further, the differences increased with the succession of the biocrusts. The contents of C, N, and P significantly increased in the biocrust layers, which were significantly higher than that of the subsoils (0-10 cm). The contents of C, N, and P in biocrusts increased by 161%, 127%, and 9%, respectively, in the later successional stage compared with that in the earlier stage. The ratios of C/N, C/P, and N/P in biocrusts were all significantly higher than in the soils beneath them (0-10 cm). Variances of C/N were lower than that of C/P and N/P, with a range from 10.0 to 11.8. The C/P and N/P ratios in the later successional stage of biocrusts were 2.4 and 2.1 times as high as that in the earlier successional stage, respectively. The slope aspect was the major influencing factor for the ecological stoichiometry characteristics of biocrusts. The ratios of C/N, C/P, and N/P were positively correlated with moss biomass and negatively correlated with soil bulk density. The recovery of topsoil nutrients was improved owing to the succession of biocrusts and the improvement of recovery appeared to be limited to a maximum depth of 2 cm under the biocrusts. Owing to the significant influences of biocrust succession on soil nutrients and their stoichiometric characteristics, and the differences between biocrusts and their subsoil, biocrusts play a crucial role for ecological restoration in arid and semi-arid regions. The results reveal the contribution of biocrusts to nutrient cycles from the perspective of soil stoichiometric characteristics and the study provides scientific basis to the ecological restoration and management in arid and semi-arid regions.
  • DownLoad:The effects of biological soil crust succession on soil ecological stoichiometry characteristics.PDF
  • Dynamic change in soil soluble nitrogen under farmland converted to forest in the Loess Hilly Region
  • Authors:ZHAO Luhong, LI Changzhen, KANG Di, REN Chengjie, HAN Xinhui, TONG Xiaogang and FENG Yongzhong
  • Abstract:Soil soluble and available nitrogen are considered to be limiting nutritional factors for the productivity of plants in terrestrial ecosystems. Land-use change has a significant impact on the physical and chemical properties of soil, particularly nitrogen pools. Furthermore, although the amounts of soil soluble nitrogen are generally very small, they can change rapidly during the plant growing season. However, the changes in soil soluble nitrogen dynamics associated with different vegetation restoration patterns are still poorly understood. Therefore, more information is essential to gain a better understanding of the changes in ecosystems dynamics that occur following the conversion of farmland to forest in the Loess Hilly Region. We studied the dynamic changes in soil soluble nitrogen from April to October, and their relation to soil moisture and temperature under three converted land types in the Loess Hilly Region[Robinia pseudoacacia(RP), Caragana korshinskii(CK), and abandoned farmland (AF)], which have undergone conversion from slope farmland (SF) for 15 years. The average densities of nitrate nitrogen (NO3--N), soluble organic nitrogen (SON), and soluble total nitrogen (STN) changed significantly from April to October in the 0-30 cm soil layer (P<0.05), although only NO3--N varied significantly with soil depth (P<0.05). During the sampling period (April to October), the average NO3--N density accounted for 5.1%-52.1% of STN, ranging from 0.13 g/m2 (in April) to 1.71 g/m2 (in October). The average density of SON varied significantly from 0.29 g/m2 (in April) to 2.92 g/m2 (in August), which accounted for 30.9%-85.3% of STN. Although the variation in ammonium nitrogen (NH4+-N) was not significant, it ranged from 0.17 g/m2 (in October) to 0.74 g/m2 (in April) and accounted for 6.4%-21.4% of STN. After long-term vegetation restoration, the average densities of NO3--N in RP, CK, and AF were 3.42, 2.54, and 1.26 times higher, respectively, than that of SF in the 0-30 cm soil layer, whereas those of NH4+-N in RP, CK, and AF were increased by 1.71, 1.37, and 1.30 times, respectively, and those of SON were increased by 1.64, 1.31, and 1.23 times, respectively, compared to SF. Correlation analyses indicated that the dynamic change in soil soluble nitrogen was affected by soil moisture and temperature, and that soluble nitrogen was more sensitive to soil moisture than to temperature. Moreover, NO3--N was more sensitive than SON and STN to soil moisture changes, whereas STN was the most sensitive to soil temperature. Collectively, these findings indicate that converting farm to forest can improve the density of soil soluble nitrogen, and increase the availability of soil nitrogen. It was also observed that the amounts of soil soluble nitrogen change significantly with different seasons.
  • DownLoad:Dynamic change in soil soluble nitrogen under farmland converted to forest in the Loess Hilly Region.PDF
  • Effects of forest gap size on the biomass and functional diversity of soil microbes in Platycladus orientalis plantations
  • Authors:GUAN Yunyun, YE Yuqian, ZHONG Yuanbiao, FEI Fei, CHEN Bin and GUAN Qingwei
  • Abstract:The metabolic activity of microbes profoundly influences underground ecological processes, similar to the soil carbon cycle. However, even though forest gap research has addressed underground processes, studies of microbial functional diversity remain scarce. In the present study, we mainly investigated changes in the microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), and microbial functional diversity (AWCD) of the soil along a horizontal gradient of large, medium, and small forest gaps (radii of 4, 8, and 12m, respectively) in a plantation of Platycladus orientalis (L.) Franco in Xuzhou (China) during the summer. The corresponding gap sizes, which were calculated as the ratio of gap radius to the height of trees at the edge of the gap, were 1.5, 1, and 0.5, respectively. Three forest gap gradients, namely, forest gap edge (D1), 4m outside the gap (D2), and 8m outside the gap (D3), were chosen. After forest gap formation, soil MBC decreased on the whole and MBN decreased significantly (P<0.05), where as the MBC/MBN ratio increased significantly (P<0.05). Among the three gap types, the MBC and MBN were lowest in the large and small gaps, respectively, with minimum levels of 2069.42 and 126.21mg/kg. Meanwhile, the MBC/MBN ratio varied from 10.50 to 19.96 and generally decreased with increasing gap size. In addition, forest gaps reduced soil AWCD, and the effect size varied with gap size, with the smallest effects observed in the small gaps. From D1 to D3, the AWCD of the small gaps initially declined and then increased, whereas it continuously increased in the medium gaps and continuously decreased in the large gaps. Furthermore, forest gaps also reduced the carbon consumption of soil microbes, and the use of carbohydrates and amino acids was the lowest in the medium gaps, whereas that of polymers was the highest in the medium and small gaps. In D1, the soil microbes consumed less carbon in the medium gaps than in the small gaps. The present study also revealed that forest gaps improved microbial functional diversity. Although there were no significant differences between the diversity (H'), richness (S), and evenness (E) indices of the three gradients, the dominance index (Ds) values of D3 and D1 were significantly higher in the small gap and control plot and were significantly greater than those of D1 and D2 in the large gap (P<0.05). The effect of forest gap on the diversity indices varied with gap scale and location. The main carbon sources used by the soil microbes were polymers and amino acids. In short, the effect size of forest gap on soil MBC, MBN, and microbial functional diversity in P. orientalis plantations vary remarkably with scale. Therefore, forest gaps can promote soil carbon sequestration and macromolecular substances degradation and improve the ability of forest ecosystems to adapt to global climate change. Furthermore, medium gaps were the most efficient for improving the ecological function of forest plantations.
  • DownLoad:Effects of forest gap size on the biomass and functional diversity of soil microbes in Platycladus orientalis plantations.PDF
  • Responses of soil microbial biomass to long-term simulated warming in Eastern Chongming Island wetlands, China
  • Authors:GAO Yanna, QI Zhiwei, ZHONG Qicheng, FAN Tong, LI Shasha, WANG Kaiyun, ZHU Hongyu and ZHOU Tingnan
  • Abstract:Climate warming is one of the main characteristics of global climate change and has a significant impact on the structure and function of terrestrial ecosystems. Soil microbial biomass is a crucial component of soil ecosystem and plays an important role in biogeochemical cycles and energy flow in ecosystems. However, soil microbial biomass is highly sensitive to environmental changes, and increase in air temperature will significantly affect soil microbial biomass. Several studies have investigated the effect of warming on soil microbial biomass, but most studies have focused on the effect of short-term simulated warming on soil microbial biomass in ecosystems such as forests, croplands, and grasslands, whereas little is known about the response of soil microbial biomass to long-term simulated warming in wetland ecosystems. Therefore, an in situ simulated warming experiment was conducted in a wetland ecosystem on Eastern Chongming Island, China. Open-top chambers (OTCs) were applied to simulate climate warming. This study investigated the effects of eight years of continuous warming on soil microbial biomass carbon and nitrogen contents at soil depths of 0-40cm in a wetland on Eastern Chongming Island. The results showed that continuous warming significantly increased soil microbial biomass carbon and nitrogen contents. From surface to deep soil layers (0-10, 10-20, 20-30, and 30-40cm), microbial biomass carbon increased by 39.32%, 70.79%, 65.20%, and 74.09%, whereas microbial biomass nitrogen increased by 66.46%, 178.27%, 47.24%, and 64.11%, respectively. However, the effect of simulated warming on soil microbial biomass at different soil depths and in different seasons did not show a uniform trend. Long-term simulated warming significantly increased soil microbial biomass carbon and nitrogen contents at the 0-20cm soil depth in April and at 0-40cm soil depth in July, but had no effect on soil microbial biomass carbon in October, although soil microbial biomass nitrogen content also significantly increased at 0-40cm soil depth. The ratio of microbial biomass carbon to microbial biomass nitrogen significantly increased in July. Correlation analysis showed that soil microbial biomass carbon and nitrogen were not significantly correlated with soil temperature, soil water content, and total nitrogen in the OTC and control group. Soil microbial biomass carbon and nitrogen contents and the ratio of microbial biomass carbon to microbial biomass nitrogen showed a positive correlation with the soil organic carbon in the OTC, but showed a negative correlation with the soil organic carbon in the control group. Thus, soil organic carbon is an important ecological factor affecting the responses of soil microbial biomass carbon and nitrogen to long-term simulated warming.
  • DownLoad:Responses of soil microbial biomass to long-term simulated warming in Eastern Chongming Island wetlands, China.PDF
  • Effects of karst soil thickness heterogeneity on the leaf anatomical structure and photosynthetic traits of two grasses under different water treatments
  • Authors:LI Zhou, ZHAO Yajie, SONG Haiyan, ZHANG Jing, TAO Jianping and LIU Jinchun
  • Abstract:Congenitally slow soil development rates and acquired rocky desertification ensure a serious shortage of soil resources in karst areas. Coupled with the steep terrain, soil distribution is uneven with a high degree of heterogeneity in space in karst regions. In the karst depression, basin, and valley areas, soil thickness and soil distribution are continuous; however, in the hill slope area, soil is usually "rock soil" or is missing. Uneven distribution of karst soil also leads to obvious spatial heterogeneity of moisture. Global precipitation changes might aggravate heterogeneity of soil moisture in soils of different thicknesses. Plant morphogenesis is very sensitive to soil moisture, including the leaf veins that control water transport and utilization and the stomata that adjust the balance of water and CO2. Simultaneously, photosynthesis that utilizes water and CO2 as raw materials is also directly affected by soil moisture. Thus, exploring the responses of the leaf anatomical structure and photosynthetic traits of plants to water availability and soil heterogeneity in karst regions is necessary to understand how precipitation changes might affect plant growth and physiology in soils of different thicknesses. Herbaceous plants, especially grasses in karst regions, are most often affected by soil heterogeneity and water availability because they mainly utilize water and nutrients from the surface soil via their fibrous root system. Two graminaceous perennial grasses, Lolium perenne L. and Festuca arundinacea Schreb. were chosen for the present study. These two species are often chosen as pioneer plants for ecological restoration and reconstruction in karst regions because of their attributes of fast growth, strong adaptive ability, and high yield, which effectively promote economic development and assist to alleviate rural poverty in harsh karst regions. In the present study, three water treatments (WCK:40 mL/d, D1:20 mL/d, and D2:12 mL/d) were combined with three levels of soil thickness[shallow soil (SS:5 cm), control (SCK:15 cm), and deep soil (SD:30 cm)] in a factorial randomized design and measurements were obtained of leaf vein and stomata traits and several photosynthetic parameters. The following results were obtained:(1) Under normal water supply conditions (WCK), the stomatal density and stomatal limitation (Ls) of L. perenne and F. arundinacea were significantly higher in the SS group than in the SCK group, and the two species net photosynthetic rate (Pn), intercellular CO2 concentration (Ci), and transpiration rate (Tr) decreased. In the SD group, the stomatal density of both species decreased, the leaf density, Pn, and Tr of L. perenne were lower than those in SCK, and the leaf density and Pn of F. arundinacea increased. (2) Under D1 water treatment, the stomatal density of L. perenne in SS was higher than that in SCK, and leaf vein, Pn, and Tr decreased; however, the stomatal density of F. arundinacea in SSshowed some decrease, and the leaf vein, Pn, and Tr of F. arundinacea were not significantly affected. In the SD group, the stomatal density of L. perenne did not change, the leaf vein increased, and the Pn and Tr were both decreased, while the stomatal density of F. arundinacea decreased and the leaf vein, Pn, and Tr increased. (3) Under D2 water treatment, the leaf veins of the two species increased in the SS group as compared to that in SCK, and their stomatal density, Pn, and Tr were suppressed. In the SD group, compared to SCK, the stomatal density of L. perenne decreased and the other parameters in both plants were not significantly affected. The results of the present study indicate that under different water conditions, the leaf anatomical structure and photosynthetic characteristics of the two plant species studied were different in response to the different thickness soils, with differences recorded between the different species. Overall, as the water content decreased, the inhibition that plant photosynthesis suffered was enhanced by a decrease of soil thickness, and the promotion effect that the deep root plant received and the inhibition that the shallow root plant suffered were first strengthened and then weakened by an increase in soil thickness. The variation of vein density and stomatal density with water content is related somewhat to the change of leaf area and leaf width.
  • DownLoad:Effects of karst soil thickness heterogeneity on the leaf anatomical structure and photosynthetic traits of two grasses under different water treatments.PDF
  • Effects of straw mulching amount on cotton growth and soil temperature in red soil drylands
  • Authors:CUI Aihua, DU Chuanli, HUANG Guoqin, WANG Shubin and ZHAO Qiguo
  • Abstract:To improve the productivity of cotton fields in red soil drylands, it is necessary to study the yield-limiting factors in these regions, and propose appropriate mitigation measures. Straw mulching is an effective method of straw resource utilization, which could effectively promote the sustainable development of agriculture. To enhance our understanding of the appropriate straw mulching amount in red soil drylands, a randomized block design field experiment was carried out in the Science and Technology Park of Jiangxi Agricultural University (115°55'02.040″E, 28°46'04.476″N, original the Agricultural College Test Station). The effects of the following four straw mulch level treatments were examined:0 kg/hm2 (S1), 4 375 kg/hm2 (S2), 8 750 kg/hm2 (S3), and 13 125 kg/hm2 (S4). The present study mainly investigated the yield, emergence rate, plant height, and chlorophyll content of cotton, and also soil temperature. The following results were obtained. (1) Straw mulching treatments increased cotton seedling emergence by 21.5%-28.1%. The difference between mulching treatments (S2-S4) and the non-mulching treatment (S1) was significant at P<0.01, although there were no significant differences among the three mulching treatments. (2) Straw mulching treatments affected the main stem growth of cotton at the late stage of growth, with treatment S4 having the best effect. (3) Straw mulching treatments also promoted an increase in chlorophyll content. Chlorophyll content in each growth period increased with an increase in the amount of straw mulching, with treatments S3 and S4 having the best effects. (4) Straw mulching treatments regulated the soil temperature. The soil temperature increased at 08:00 and 20:00, but decreased at 14:00, although the daily temperature range showed only a small variation. The effect of temperature control was weakened gradually in the straw mulching treatments with an increase in soil depth. This effect was highly correlated with daily mean temperature difference and soil depth during the coverage period, and the correlation coefficient reached 0.98 or higher, which aided in predicting the variation in diurnal temperature range of different soil layers. (5) Straw mulching treatments promoted a highly significant (P<0.01) increase in cotton production, with production in treatments S2, S3, and S4 being 11.4%, 35.9%, and 37.7% higher, respectively, than that in the non-mulching treatment (S1). There was also a gradual increase in yield with an increase in the amount of mulching. Collectively, these results indicate that straw mulching can play an important role in improving cotton yield, seedling emergence rate, plant height, and chlorophyll content, and also in regulating soil temperature in red soil drylands. In this regard, straw mulching at 8 750-13 125 kg/hm2 was considerably effective, which would not only be conducive to the production of cotton but could also reduce environmental pollution caused by the burning of straw and improve the utilization of straw resources, and is thus worth popularizing in red soil drylands. However, since the present study was only of a short duration, further long-term studies in red soil drylands are required, particularly with regards to the mechanisms underlying the effects of mulching on the growth of cotton.
  • DownLoad:Effects of straw mulching amount on cotton growth and soil temperature in red soil drylands.PDF

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