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Volume 38,Issue 7
  • Soil bacterial and fungal community succession along an altitude gradient on Mount Everest
  • Authors:ZHANG Dandan, ZHANG Limei, SHEN Jupei and WANG Mu
  • Abstract:Alpine ecosystems are special regions and are sensitive to global climate change. Revealing the succession of microbial communities along the altitude gradients, especially above the permanent snow line, is essential to understanding the influence of global climate change on the alpine ecosystem and the climate feedback of the alpine ecosystem. In this study, the abundance and community composition of bacteria and fungi in 12 soil and gravel samples collected from the northern slope of the Mount Everest (Tibetan Plateau) along an altitude gradient varying between 4000 and 6550m (above sea level, m.a.s.l.) were characterized by viable counting, real-time polymerase chain reaction (PCR), phospholipid fatty acid (PLFA), and denaturing gradient gel electrophoresis (DGGE), combined with clone sequencing. The results showed that both the viable count and rRNA gene abundance for bacteria and fungi decreased with increasing altitude. The PLFA analysis showed that the contents and diversity of bacterial, fungal, and total PLFA reduced with increasing altitude. Furthermore, none of the PLFA components representing gram-positive bacteria were detected in samples above snow line (5350m), but some PLFA components representing gram-negative bacteria and fungi were distributed in all samples for low and high-altitude areas, which suggested that gram-positive bacteria were more sensitive to the changes in altitude and altitude-dependent environmental variables. The unweighted pair-group method with arithmetic means (UPGMA) analyses of the DGGE profiles showed distinct clustering in the low-altitude (4000m) and high-altitude (≥ 5350m) samples for bacteria communities, but not for fungal communities. The DGGE band sequencing results suggested that Proteobacteria were the dominant bacteria in all samples, and that Gemmatimonadetes were dominant in higher altitude samples, whereas Actinobacteria were mainly found in lower altitude samples. Fungal DGGE band sequencing showed that Ascomycota predominated across the altitude gradient, whereas Cercozoa protists, identified by the fungal 18S rRNA gene primer, were only found in relatively higher altitude samples.
  • DownLoad:Soil bacterial and fungal community succession along an altitude gradient on Mount Everest.PDF
  • Soil enzyme activities, soil and leaf litter nutrients of typical vegetation in Ziwuling Mountain
  • Authors:ZHANG Haixin, ZENG Quanchao, AN Shaoshan, WANG Baorong and BAI Xuejuan
  • Abstract:In China, vegetation restoration is an effective way of protecting soil from erosion and ensuring water conservation on the Loess Plateau. Soil nutrients and enzyme activities are sensitive parameters for assessment of soil remediation through vegetation restoration. There are positive relationships between leaf litter and soil nutrient contents. This study aimed to provide scientific basis for plant selection, and to evaluate the effectiveness of plant selection for vegetation restoration. We collected the soils and leaf litter under five main forest communities of Ziwuling Mountain and analyzed basic soil physical and chemical properties, enzyme activities (urease, sucrase and alkaline phosphatase), and leaf litter nutrients. Statistical analyses were conducted using Analysis of Variance and using Pearson correlation analysis hoping to reveal the driving factors of the differences between soil enzyme activities under different vegetation types. The results showed that:(1) In leaf litter:soil total nitrogen (TN) content of the soil under Robinia pseudoacacia and Quercus wutaishanica vegetation types were 17.10g/kg and 16.26g/kg, respectively, which were higher than the other vegetation types. Total phosphorus (TP) content of the soil under Q. wutaishanica was the highest (1.83g/kg), while soil organic carbon (SOC) content was the highest (501.02g/kg) under the Pinus tabuliformis vegetation. (2) For soil samples, the soil under R. pseudoacacia had the lowest SOC (6.76g/kg) and TN (0.70g/kg) contents, had the highest TP content (0.61g/kg). The Quercus wutaishanica had highest SOC (19.18g/kg) and TN (1.60g/kg) contents, but had the lowest content TP (0.55g/kg). (3) For soil enzyme activities, alkaline phosphatase activity was in the order of Platycladusorientalis > P. tabuliformis > B. platyphylla > Q. wutaishanica > R.pseudoacacia. Urease activity followed a different order:Q. wutaishanica > P. orientalis > B. platyphylla > P. tabuliformis > R. pseudoacacia, while sucrase activity was in the order of P. orientalis > Q. wutaishanica > P. tabuliformis > B. platyphylla > R. pseudoacacia. (1) Comparing the C, N, and P contents and C/N ratios of leaf litter and soils of the five main forest communities, revealed that the decomposition rate of leaf litter of R. pseudoacacia was the fastest, while that of leaf litter of P. tabuliformis was the slowest. Though leaf litter of R. pseudoacacia had higher decomposition rate than other forests and released most of the nutrients, little nutrients entered into soil and it was not conducive to store and accumulate nutrients in forest soil. R. pseudoacacia specie of plantation forests may be unconsidered in Ziwuling Mountain.(2) In the zone, soil enzyme activity is mainly affected by vegetation types, soil carbon, nitrogen, bulk density and pH, and no significant correlation with phosphorus. In the process of vegetation restoration and artificial afforestation, the increasing of soil carbon and nitrogen contents are main factors to improve the soil enzyme activity.(3) Although artificial afforestation can improve enzyme activity and soil fertility, however, it has not reached the natural level of secondary forest.
  • DownLoad:Soil enzyme activities, soil and leaf litter nutrients of typical vegetation in Ziwuling Mountain.PDF
  • Effect of adding a combination of nitrogen and phosphorus on fine root morphology and soil microbes of Machilus pauhoi seedling
  • Authors:WANG Yan, ZHONG Quanlin, XU Chaobin, ZHANG Zhongrui and CHENG Dongliang
  • Abstract:One-year old seedlings of Machilus pauhoi were used to determine the effect of adding a combination of N and P on the morphology of different orders of fine roots and soil microbes. For this, the phospholipid fatty acid (PLFA) analysis and root system scanning methods were used. The results were as follows:(1) Combined addition of N and P significantly improved (P < 0.05) specific root length and specific root area of the first-order and second-order fine roots, while it reduced specific root area of the third-order and fourth-order roots. (2) Root tissue density for the first-order and second-order fine roots tended to decline, contrary to that for the third-order and fourth-order. (3) Root average diameter of the first-order to the fourth-order roots was significantly reduced (P < 0.05). (4) Total microbial, fungal, and bacterial biomass all showed a tendency to reduce after first increasing, all reaching the maximum when treated with N:P in the ratio of 10:1. (5) Although the bacterial and fungal and actinomycetes biomass and total microbial were significantly and positively correlated with specific root length and specific root area for the first-and second-order roots, they were negatively correlated for the fourth-order roots. Although Gram-positive bacteria and fungal biomass were positive correlated with root tissue density for the third-order and the fourth-order, no significant correlations with the first-and second-order roots were observed. Root average diameter for all orders had no significant correlation with soil microbes. Our results suggest that the effect of short-term addition of a combination of N and P was the best when treated with N:P in the ratio of 10:1, which can improve the efficiency of nutrient uptake of Machilus pauhoi seedlings' fine roots. Plants may adapt to N deposition by adjusting the fine root morphological characteristics. Meanwhile, the response of underground biological communities such as soil microbes, and the relationship of microbes with fine roots, to N deposition also changes, which affects C and N cycles and the nutrient flow in underground ecosystem.
  • DownLoad:Effect of adding a combination of nitrogen and phosphorus on fine root morphology and soil microbes of Machilus pauhoi seedling.PDF
  • Effects of nitrogen additions on soil microbial respiration and its temperature sensitivity in a Tibetan alpine meadow
  • Authors:YE Chenglong, ZHANG Hao, ZHOU Xiaolong, ZHOU Xianhui, GUO Hui and HU Shuijin
  • Abstract:The soil C stock of the Tibetan Plateau is of global significance because of its large pool size and the potential positive feedback to climate warming. Soil microbial respiration is an important carbon (C) flux of the global C cycle, and is greatly affected by soil nitrogen (N) availability. Reactive N inputs often reduce soil microbial respiration, but how they affect the temperature sensitivity of soil microbial respiration is still poorly understood. Here, we examined the effect of N additions on soil microbial respiration and its temperature sensitivity (expressed as Q10), and assessed the relative importance of substrate availability and the chemical composition of soil organic C in explaining the variation in soil microbial respiration and Q10. A 4-year field experiment with four simulated N deposition levels, 0, 5, 10, and 15g N m-2 a-1 was conducted. Soil samples were collected from three levels of nitrogen addition rate (0, 5, and 15g N m-2 a-1) and incubated at 5℃, 15℃ and 25℃ in the laboratory. The results showed that N additions significantly increased soil dissolved organic C and available N (P < 0.05), but did not significantly affect soil pH, soil organic C, total N, available P, and total P. Moreover, N additions did not affect microbial biomass C, but significantly decreased microbial biomass N (P < 0.05). The solid-state 13C nuclear magnetic resonance showed that N additions decreased the relative content of O-alkyl C, but increased the relative contents of alkyl C, aromatic C, and carboxylic C, which resulted in higher aromaticity and aliphaticity of soil organic carbon under N addition treatments than that of the control treatment. We also found that N additions significantly decreased soil microbial respiration rate and cumulative C efflux under three temperatures (P < 0.05), but significantly increased Q10 under the incubation temperature of 15℃ and 25℃ (P < 0.05). Linear correlation analysis showed that microbial respiration was negatively correlated with the complexity of soil organic C, whereas Q10 under the incubation temperature of 15℃ and 25℃ was positively correlated with the complexity of soil organic C. These findings support the prediction based on kinetic theory that soil organic C, with recalcitrant molecular structure, has a high temperature sensitivity of respiration. Together, our results suggest that changes in chemical structure of soil organic C induced by N inputs may play an important role in regulating the response of soil microbial respiration to elevated temperature, and further increase the uncertainty in predicting net soil C losses in the scenario of warming on the Tibetan Plateau.
  • DownLoad:Effects of nitrogen additions on soil microbial respiration and its temperature sensitivity in a Tibetan alpine meadow.PDF
  • Effects of Dicranopteris dichotoma on soil dissolved organic carbon in severely eroded red soil
  • Authors:REN Yinbang, LÜ Maokui, JIANG Jun and XIE Jinsheng
  • Abstract:Understory, an important component of the forest ecosystem, plays an important role in maintaining forest structure and soil quality. To analyze the relationship between soil dissolved organic carbon (DOC), belowground biomass, and DOC leachates of aboveground biomass, we conducted a comparative experiment of the presence or absence of understory Dicranopteris dichotoma on severely eroded red soil. The results showed that the aboveground and belowground biomass, and the content of soil DOC increased significantly with understory D. dichotoma coverage (P < 0.05); the effect of D. dichotoma on the surface soil (0-20cm) was greater than the deep soil (20-100cm) (P < 0.05). The correlation analysis showed that there was a significant positive correlation between soil DOC storage and fine root biomass (P < 0.05), indicating that the vertical distribution of underground roots directly affects the soil DOC reserves. Moreover, there was a significant positive correlation between soil DOC with fresh leaf (Pinus massoniana and D. dichotoma) and litter (P. massoniana and D. dichotoma) leachates during vegetation restoration (P < 0.01), but there was only a significant correlation with fresh leaf (P. massoniana) leachates in the bare ground (P < 0.05). The effect of the litter leachates on the soil DOC storage was higher than the fresh leaves. The soil microbial biomass carbon and microbial entropy in D. dichotoma-covered land were significantly higher than bare land in the process of vegetation restoration. Therefore, D. dichotoma may provide more substrates to participate in soil material and nutrient cycling, contributing greatly to soil DOC, which further provides important nutrient reabsorption sources for restoration of P. massoniana forest in eroded areas. It is possible that D. dichotoma coverage increases microbial activity and promotes assimilation of soil microorganisms; thereby playing an important role in the accumulation of soil organic carbon by improving utilization of microbial carbon sources.
  • DownLoad:Effects of Dicranopteris dichotoma on soil dissolved organic carbon in severely eroded red soil.PDF
  • Application of three drought indexes in soil moisture inversion using remote sensing in marsh wetlands of arid area
  • Authors:GE Shaoqing, ZHANG Jian, SUN Wen, WANG Liping, GENG Yajun and FAN Shuangping
  • Abstract:Wetland hydrological conditions play a key role in the structure and function of the wetland ecosystem. In this study, we use three drought monitoring methods, Temperature Vegetation Dryness Index (TVDI), Perpendicular Drought Index (PDI), and Normalized PDI (NPDI) as well as soil moisture observation data in the field to study marsh wetlands of an arid area in the middle and lower reaches of the Shule River using a remote sensing technology based on the Landsat8 Operational Land Imager (OLI). We obtained the following results in this study:1) TVDI, PDI, and NPDI were significantly negatively correlated with soil moisture in different soil layers (P < 0.01), the goodness of fit among the three drought indexes was in the following order of magnitude NPDI > TVDI > PDI with soil moisture in different soil layers, and the fitting results using the NPDI index were the best with topsoil moisture; 2) there were numerous significant differences in soil moisture among different soil layers of the same marsh type (P < 0.05), and an increasing trend in the soil moisture of different marsh types was observed with increasing soil depth; 3) the soil moisture was significantly different between different marsh types of the same soil layer (P < 0.05), and the comparison of soil moisture in the different soil layers showed the following decreasing order of magnitude:marsh meadow > herbaceous marsh > seasonal saline marsh > inland salt marsh.
  • DownLoad:Application of three drought indexes in soil moisture inversion using remote sensing in marsh wetlands of arid area.PDF
  • Effects of grazing on nitrogen transformation in swamp meadow wetland soils in Napahai of Northwest Yunnan
  • Authors:WANG Xue, GUO Xuelian, ZHENG Rongbo, WANG Shanfeng, LIU Shuangyuan and TIAN Wei
  • Abstract:In this study, the typical swamp meadow wetland in Napahai, a Wetland of International Importance, in Northwest Yunnan was selected as the research site. Nitrogen transformations in swamp meadow wetland soils under the influence of grazing disturbance were measured and analyzed using in situ column interior control experiment methods. The results showed that the soil bulk density and pH were increased, and the soil moisture content, total organic carbon content, total nitrogen content, and NH4+-N content were decreased in surface soils with grazing disturbance. The mineralization and nitrification rates of swamp meadow wetland soils with the influence of grazing disturbance showed a significant decrease:pig arch > cattle-trampled > control. Both pig arch and cattle-trampled sites enhanced the mineralization and nitrification rates. Denitrification rates of swamp meadow wetland soils with the influence of grazing disturbance showed a significant decrease:pig arch > control > cattle-trampled (P < 0.05). Pig arch sites promoted N2O release but cattle-trampled sites inhibited N2O release. In contrast, both the mineralization and nitrification rates of swamp meadow wetland soils with the grazing disturbance had a significant positive correlation with soil bulk density and pH, and a significant negative correlation with soil moisture content, NH4+-N content, TOC, and TN. Denitrification rate had a significant negative correlation with TOC.
  • DownLoad:Effects of grazing on nitrogen transformation in swamp meadow wetland soils in Napahai of Northwest Yunnan.PDF
  • Effects of fertilization on soil respiration, heterotrophic respiration, and temperature sensitivity in an oil tea plantation
  • Authors:SHAO Rui, ZHAO Miaomiao, ZHAO Fen, SHEN Ruichang, LIU Lixiang, ZHANG Liyun and XU Ming
  • Abstract:As the largest carbon pool of terrestrial ecosystems, soils constitute important sources and sinks of global CO2 balance. Soil respiration is an important pathway of carbon fluxes between the atmosphere and terrestrial ecosystems. Further, soil respiration can also influence terrestrial carbon cycling through climate feedbacks, specifically temperature sensitivity (Q10). Oil tea (Camellia oleifera) is an important native woody oil crop, and has been widely developed in south China in recent years. High-level fertilization has been widely adopted to increase growth of oil tea trees and maintain soil fertility. In this study, the effects of fertilization on soil respiration, heterotrophic respiration and temperature sensitivity in an oil tea plantation were examined. Static chambers and gas chromatography were used to collect and analyze gas samples. To differentiate soil respiration and soil heterotrophic respiration, the trenching method was used. There were four treatments in this study:oil tea plots with fertilization (OF), oil tea plots without fertilization (CK), trenching plots with fertilization (OF-T), and trenching plots without fertilization (CK-T). The results showed that fertilization had no significant effects on either soil respiration or heterotrophic respiration. Soil CO2 effluxes in different treatments (OF, CK, OF-T, CK-T) were 77.91±2.59, 73.71±0.97, 66.82±1.02, and 66.84±3.94 mg C m-2 h-1, respectively. The temperature sensitivity of soil CO2 effluxes was 1.77±0.01, 1.75±0.03, 1.96±0.01, 1.79±0.03 in OF, CK, OF-T, and CK-T respectively. Fertilization significantly increased temperature sensitivity of soil heterotrophic respiration, with the Q10 values in the OF-T plots significantly higher than those in the CK-T plots. In addition, fertilization significantly increased soil NH4+-N and NO3--N contents in the surface layer (0-10cm). We also found significant linear relationships between the Q10 of soil CO2 effluxes and soil NH4+-N, as well as NO3--N contents. Our findings may provide basic data for greenhouse gas inventories and understanding their responses to climate change in a typical cash crop plantation in south China.
  • DownLoad:Effects of fertilization on soil respiration, heterotrophic respiration, and temperature sensitivity in an oil tea plantation.PDF
  • The effects of warming and nitrogen addition on soil nutrients in the soil solutions from a subtropical Cunninghamia lanceolata plantation
  • Authors:YUAN Xiaochun, YANG Jingqing, WANG Zheng, YUAN Shuo, YANG Zhouran, CHEN Yuemin and YANG Yusheng
  • Abstract:Climate change can alter soils by causing warming and nitrogen deposition. It is not clear whether the nutrient supply balance in the soil solution plays an important role in accelerating or weakening soil nutrient cycling. The aim of this study was to analyze the effects of warming and nitrogen addition on nutrients in the soil solutions taken from a subtropical Cunninghamia lanceolata plantation. Soil solution collectors were installed at soil depths of 0-15, 15-30, and 30-60cm in every sample plot. The soil solutions were collected using the negative pressure supplied by a vacuum pump, and the dynamic changes to the organic and inorganic components were analyzed for two years. The results showed that warming and warming+N addition significantly inhibited the dissolved total nitrogen (DTN) and NO3- concentrations in all the soil layers, and N addition had no significant effect on them due to the increase in mass vegetation absorption of these nutrients. In general, the short-term treatments of warming and N addition significantly decreased the concentrations of dissolved organic carbon (DOC), but had little effect on the K+, Ca2+, Na+, and Mg2+ concentrations in the soil solution. However, the effect of warming on the mineral elements in the soil solution was much greater than that of N addition. Warming increased the soil pore-size and permeability, which greatly promoted Fe3+ and Al3+ leaching and decreased Na+ and Mg2+ concentrations in the surface soil. The interaction between warming and N addition may have a combined effect that is more than the simple addition of a single factor. Therefore, further long-term monitoring to understand the internal mechanism of soil nutrient response to future climate change is needed.
  • DownLoad:The effects of warming and nitrogen addition on soil nutrients in the soil solutions from a subtropical Cunninghamia lanceolata plantation.PDF
  • Effect of the humidity/aridity gradient on the ecological stoichiometry of soil and leaves in Xishuangbanna tropical rainforest
  • Authors:LU Tongping, WANG Yanfei, WANG Liming, LIN Yongjing, WU Mengjuan, ZHANG Wenxiang and NIU Jie
  • Abstract:This study investigated the humidity/aridity gradient effects and ecological stoichiometry in Xishuangbanna tropical rainforest. The geographical pattern, characteristics of ecological stoichiometry and its response to altitude and humidity/aridity effects were studied in the soil and plants of Xishuangbanna tropical rainforest using field and laboratory analyses. The results showed that the ecological stoichiometry of soil and leaves in Xishuangbanna rainforest was influenced by altitude and humidity gradients, to varying degrees. The hydrothermal gradient of seasonal and montane rainforests was affected by altitude. The soil moisture content had a significant effect on soil organic carbon (SOC) (P < 0.01) in dry and wet seasons, which was significantly controlled by the altitude gradient. The effect of soil moisture content on soil total nitrogen (STN) and soil total phosphorus (STP) was more significant during the rainy season. The total phosphorus (TP) content in leaves increased with increasing water content, and the variation trend of leaf TN content in the dry season was consistent with the TP content. However, water content reduced the total nitrogen (TN) content when it increased to a certain extent during the rainy season. The significant correlation among soil moisture in the dry season, altitude, and the C/P of soil, similar to the correlation between C/N and water content of leaves in the dry season, indicated that the level of soil water content determines the mineralization of soil phosphorus and the ability of plants to absorb P under the water shortage. Leaf C/N has obvious implications for the feedback moisture content of plants. This further illustrates that the hydrothermal gradient is an important driver for the stoichiometry characteristics of soil-leaf ecosystems. Additionally, high temperature and rain may weaken the assimilation capacity of leaf C content in a seasonal rainforest, and leaf N content may decrease in terms of regional response to global change. Furthermore, the elemental cycles of soil-leaf systems would be shortened, and the dry season may weaken the limiting effect of P in plant ecosystems of montane rain forests because of the coupling effects of P cycles to other elements.
  • DownLoad:Effect of the humidity/aridity gradient on the ecological stoichiometry of soil and leaves in Xishuangbanna tropical rainforest.PDF
  • Effects of simulated insect herbivory on the growth and chemical defense of Alternanthera philoxeroides in different habitats
  • Authors:GAO Fanglei, GUO Sumin, YAN Ming, LI Junmin and YU Feihai
  • Abstract:Alien invasive plant species can invade various habitats and be grazed upon by different insects. Therefore, habitat conditions may affect the strategies of alien invasive plant species to defend against insect herbivory. We conducted a greenhouse experiment in which we grew ramets of the invasive herb Alternanthera philoxeroides collected from three different habitats (aquatic, semi-aquatic and terrestrial) and subjected them to two levels of simulated leaf herbivory, i.e. no defoliation (control) and 50% leaf removal. Simulated leaf herbivory significantly reduced root biomass, stem biomass, leaf biomass and total biomass of A. philoxeroides, but had no significant effect on root/shoot ratio, root mass ratio, stem mass ratio and leaf mass ratio. Root biomass, stem biomass, leaf biomass and total biomass of A. philoxeroides were higher in terrestrial environments than in semi-aquatic and aquatic environments, but root/shoot ratios in terrestrial habitats were significantly lower than in semi-aquatic and aquatic habitats. Simulated leaf herbivory significantly decreased lignin content of A. philoxeroides, but had no significant effect on the contents of tannins and phenols. Habitat types had no significant effect on lignin content of A. philoxeroides, but tannin content was significantly higher in terrestrial habitats than in semi-aquatic and aquatic habitats, and phenol content was also significantly higher in terrestrial habitats than in semi-aquatic habitats. These results suggest that the chemical defense of A. philoxeroides to insect herbivory may be higher in terrestrial habitats than in aquatic and semi-aquatic habitats. Total biomass of A. philoxeroides was significantly negatively correlated with phenol content under simulated leaf herbivory, and was significantly positively correlated with tannin content under both control and simulated leaf herbivory treatments. However, total biomass was not correlated with lignin content. These results indicate that insect herbivory can trigger a trade-off between growth and chemical defense in A. philoxeroides, i.e., herbivory results in investing in chemical defense at the cost of reduced growth, and habitat conditions have little effect on such a trade-off.
  • DownLoad:Effects of simulated insect herbivory on the growth and chemical defense of Alternanthera philoxeroides in different habitats.PDF
  • Impacts of rainfall on leaf PM (airborne particulate matter) detention in five commonly used urban tree species in northern China
  • Authors:LIU Chenming, ZHANG Zhiqiang, CHEN Lixin, ZOU Rui, ZHANG Lu, GAO Yuan and LI Dongmei
  • Abstract:It is widely acknowledged that urban trees and forests can significantly improve air quality by removing airborne particulate matter (PM) and thus safeguard the health of urban residents. However, it is very difficult to accurately assess the ability of tree species to capture PMs from the air as such processes are governed by several biotic and abiotic factors. Here, we present a first ever study that explores the effects of rainfall on the detention of PMs by leaves in five commonly used urban greening species in northern China, including Ginkgo biloba, Acer mono Maxim, Euonymus japonicus, Koelreuteria paniculata, and Eucommia ulmoides. Our specific objectives were to:1) quantify how much PMs detained on the leaves of five different tree species can be washed off by natural and simulated rainfall events, 2) compare the difference in PM removal between tree species under different amounts of rainfall, and 3) analyze the factors that might contribute to the differences in PM removal under different rainfall conditions. Leaves were uniformly collected from top, middle, and bottom layers of the tree canopy at four cardinal directions from the sampling trees after several minutes of rainfall and 12 days after rainfall. Each sampled tree leaf was sealed in a plastic bag immediately after collection. To measure the quantity of PMs trapped on leaves, the samples were washed and water used for washing was collected. Thereafter, 10% of the water was dried to determine the weight of total suspended particulates (TSP), while the remaining 90% of the water was passed through a 10μm mesh filter and then through a 2.5μm mesh filter. These filters were then dried to determine the weight of PM > 10μm (PM > 10) and PMs that were between 2.5 and 10μm (PM10-2.5). Then, 20% of the filtered water was dried to determine the weight of PMs that were < 2.5μm (PM2.5). Once the quantity of airborne particulate matter held per unit leaf area was determined for each of the study species, leaves were sampled after exposure to the following rainfall conditions:light rain (14mm), moderate rain (29mm), 30mm/h indoor simulated rain (equal to 15mm), and 12 days after rain (to determine the saturated dust held in summer). The result indicated that the amount of PM washed off from the leaves by rainfall varied greatly with the size of the particulates and the rainfall condition (including the intensity and amount of precipitation). For all species except Ginkgo biloba, PM10 could be washed off even under light natural rainfall condition and the amount and intensity of rainfall were critical factors in controlling PM removal. Overall, 50% and 90% of the TSP were removed by moderate rainfall and simulated torrential rainfall, respectively, due to higher intensity of rainfall. One major factor that contributes to the above observations is the surface structure of leaves:smooth surfaces, like leathery leaves, have better ability to trap PMs, which also wash-off more easily. Among the five species, Euonymus japonicus recorded the best overall absorption of particulates (washed TSP:(775.06±33.99)mg/m2, light rain), while Ginkgo biloba had an edge on absorbing particulates of small sizes (washed PM2.5:(426.55±40.83.99)mg/m2, moderate rain). We concluded that the species differed in their ability to trap airborne PMs and in the rate of removal of PM from the leaves by a rainfall event, and this was influenced by the differences in the surface structure of leaves of the species, rainfall amount and intensity, as well as the particulate size.
  • DownLoad:Impacts of rainfall on leaf PM (airborne particulate matter) detention in five commonly used urban tree species in northern China.PDF
  • Physiological and biochemical response of typical shrubs to drought stress in the Minjiang River dry valley
  • Authors:HE Jianshe, ZHANG Li, LIU Qianli, ZHU Xinwei, LIU Xingliang, FENG Qiuhong, LUO Da and SHI Zuomin
  • Abstract:Physiological process is essential for plant growth, and is sensitive to environmental change. The Minjiang River dry valley in the upper reaches of the Yangtze River is increasing as it is affected by human activity, environmental changes, and their interactions under global climate change scenarios. Water deficit is a major limiting factor in vegetation recovery in this region. Therefore, evaluation of the physiological and biochemical levels is important to determine drought stress adaptations in plants and the selection of drought-tolerant plants. The aim of this study was to investigate the adaptation mechanisms of selected shrubs to drought stress in the Minjiang River dry valley, and to provide a reference for selecting drought-tolerant shrubs. We selected six mountain shrubs from this region, including Hippophae rhamnoides, Bauhinia faberi, Sorphora davidii, Caragana arborescens, Berberis sargentiana, and Cotinus szechuanensis. We evaluated changes of anti-oxidant protective enzyme activities, membrane injury indexes, and osmotic adjustment substances in leaves of these shrubs subjected to increasingly severe drought conditions, using pot experiments. The results showed that the responses of different anti-oxidant protective enzymes of these shrubs to drought stress and subsequent oxidative stress were different. In all six shrubs, superoxide dismutase (SOD) activities first increased and then decreased with prolonged drought stress, peroxidase (POD) activities increased gradually as drought stress continued, whereas catalase (CAT) activities increased in the middle and late stages of drought stress, indicating various protective enzymes could be playing inter-coordinating roles at different stress stages. Malondialdehyde (MDA) in all shrubs showed a slow increase with the prolonged drought stress, indicating that the membrane lipid peroxidation of cells gradually increased, and plants began to experience toxicity. With prolonged drought stress, the membrane permeability of H. rhamnoides and B. faberi initially increased, then decreased, and finally returned to the initial level at the end of the stress period, probably because these two shrubs obtained drought resistance by drought hardening. Membrane permeability of S. davidii and C. szechuanensis remained unchanged between 0 and 4 days when exposed to drought stress, and then sharply increased after 8 days, and then was maintained at a relatively high level. These findings implied that the membrane structure and function of these two plants was still intact and physiological activities could still proceed normally at early stages of drought stress; however, the cell membranes suffered serious damage during the middle stages of drought stress. In all six shrubs, proline contents increased with increased drought stress, indicating that drought stress resulted in proline accumulation and thus improved cell osmotic adjustment capabilities. Principal component analysis can provide a quantitative evaluation of the different physiological and biochemical indexes for the seedlings under drought, which indicated that the six shrubs could be ranked from the most to least drought resistant as follows:B. faberi, H. rhamnoides, C. arborescens, C. szechuanensis, S. davidii, B. sargentiana. The study revealed that all six shrubs positively responded to drought stress through improved antioxidant enzyme activity and the accumulation of osmotic adjustment substances, which could help to reduce reactive oxygen injury, improve osmotic adjustment capabilities, and reduce cell damage.
  • DownLoad:Physiological and biochemical response of typical shrubs to drought stress in the Minjiang River dry valley.PDF
  • Effect of drought on leaf gas exchange in Summer Maize
  • Authors:MA Xueyan and ZHOU Guangsheng
  • Abstract:A large number of studies have been carried out to investigate how crop photosynthesis responds to drought, but few have investigated the response of crop leaf gas exchange to drought processes, and their response thresholds. Based on a prolonged drought experiment in summer maize conducted in 2013, which included five watering treatments, and began from the 7-leaf stage, we investigated how drought developed with different initial amounts of irrigation, and how leaf gas exchange parameters changed as the drought progressed. Then, we determined the thresholds of soil and leaf moisture content when leaf gas exchange parameters began to respond to drought. The results showed that treatments with different initial amounts of irrigation induced different drought processes. Drought occurred earlier, persisted longer, and was more severe with treatments receiving less irrigation. The net photosynthetic rate (Pn), transpiration rate (Tr), and stomatal conductance (Gs) of summer maize under different watering treatments decreased sharply at the initial stage of drought; however, these parameters declined slower as drought prolonged, and tended to be almost identical to those growing under normal environment conditions. This indicated the acclimation of maize photosynthesis in response to prolonged drought. The onset of agricultural drought was typically marked by a decline in soil moisture below a critical point, which significantly impact crops. As drought progressed, the plant constituents and physiological processes could be altered sequentially, while lower-level responses would lead to changes in higher-level responses, and eventually changes at an individual plant level. Plant leaf gas exchange was found to be more directly affected by leaf water status than soil moisture content. Therefore, we identified the tipping points when maize leaf gas exchange parameters started to be affected by drought based on the tolerance limits of normal distribution; these were then quantified by soil moisture and leaf moisture content, respectively. The results showed that, Pn, Tr, and Gs decreased sharply when the relative soil moisture of 0-30cm depth was lower than 53%, 51%, and 48%, respectively, and leaf moisture content was lower than 81.8%, 81.3%, and 81.2%, respectively. At the initial stage of drought, the intercellular CO2 concentration (Ci) decreased, and stomatal limitation value (Ls) increased, indicating that stomatal closure accounted for the major decline in maize photosynthesis. As drought progressed, Ci increased while Ls decreased, indicating that non-stomatal limitation, other than stomatal closure, contributes to the major decreases in maize photosynthesis. The point at which the dominant limiting factor of maize photosynthesis converted from stomatal to non-stomatal varied under different treatments. The conversion time was earlier in maize that received lower initial amounts of irrigation due to longer persistence and greater severity of drought, and later in maize that received relatively higher initial amounts of irrigation. However, the thresholds of relative soil moisture and leaf moisture content when the conversion occurred were almost identical under all five treatments. The critical relative soil moisture of 0-30cm depth was about 44%±2% and the corresponding leaf moisture content was about 77.6%±0.3%. The results could provide reference information for drought monitoring and assessment of summer maize.
  • DownLoad:Effect of drought on leaf gas exchange in Summer Maize.PDF
  • Grassland vegetation cover inversion model based on random forest regression: A case study in Burqin County, Altay, Xinjiang Uygur Autonomous Region
  • Authors:CHEN Yan, SONG Yuqin and WANG Wei
  • Abstract:As a large country with extensive grassland resources, China is facing severe grassland degradation. Studying trends in grassland vegetation cover change provides a basis for identifying the driving forces of grassland degradation and associated risk assessment. In previous studies, parametric regression models have typically been applied to estimate vegetation cover. However, the harsh assumptions of parametric regression have always been neglected. In the current study, vegetation cover monitoring data and vegetation indices (NDVI, SAVI, MSAVI, EVI), extracted from Landsat remote sensing images, were used to build random forest regressions, which are non-parametric models. These models were subsequently compared with traditional linear regression models. To build and test these models, 205 samples were collected from 2010 to 2015 (data from 2012 were not included) in alpine meadow, mountain meadow, lower-flat meadow, temperate meadow steppe, desert steppe, steppe desert, and desert in Burqin County, Xinjiang Uygur Autonomous Region. Among these samples, 150 samples were used to build models, and the remainder was used as testing data. Two sets of Landsat remote sensing images, Level 1 Standard Product and Surface Reflectance Product, were applied separately, and both included TM data for 2011-2012 and OLI data for 2013-2015. In total, two random forest models and 23 linear models were built. The results indicated that the predictive ability of the random forest models was clearly stronger than that of most of the linear models. Moreover, it was not necessary to test the assumptions for the random forest models, whereas none of the linear models' assumptions in this study could be satisfied perfectly. In the case study, random forest regression was applied to estimate the trend in grassland vegetation cover change in the last decade in the study area based on 663 sampling points. Among these, data for 2005-2009 were based on Landsat ETM+, data for 2010-2011 were based on Landsat TM, and data for 2013-2015 were based on Landsat OLI. It was clear that sensor differences would have a certain influence on the inversion results. Therefore, we also simultaneously built a random forest model for MODIS-EVI data, as this would not be affected by sensor differences, and the results calculated using MODIS data were considered to be a standard. For Level 1 standard data, the results based on Landsat ETM+ were significantly smaller than the results based on MODIS data. For surface reflectance data, the influence of different sensors on the results could be markedly reduced. Finally, to quantify the uncertainty of vegetation cover change trend based on surface reflectance data, we used a random forest model to verify vegetation cover extracted from different sensors during the same period, and found that the uncertainty was between -10% and 11%. In conclusion, random forest regression is assumed to be a better model to inverse vegetation cover than linear models. For its application in time series studies, Landsat surface reflectance production could significantly reduce the influence of sensor difference, although the uncertainty was still approximately ±10%. In the current study, we assessed many grassland types, and to improve the accuracy of prediction, vegetation indexes should be calculated separately in further studies. In addition, efforts should be made to reduce the uncertainty associated with the data from different types of sensor.
  • DownLoad:Grassland vegetation cover inversion model based on random forest regression: A case study in Burqin County, Altay, Xinjiang Uygur Autonomous Region.PDF
  • A coordinated decomposition between leaf litter and absorptive roots across eight temperate and subtropical tree species in China
  • Authors:FAN Pingping, LÜ Meirong, LI Xueying, SHI Xiaomei and LÜ Jing
  • Abstract:Leaves and fine roots ( < 2mm) account for the majority of annual litter production in forests. Whether their decomposition is coordinated would largely influence species effects on terrestrial ecosystem C cycling. Currently, the relationship between leaf and root decomposition is still highly uncertain, which may be caused by the ambiguous and arbitrary definition of fine roots. Within fine roots, only the distal root tips (R1) or root branches (R1-3) are functionally comparable to leaves as resource acquisition organs (absorptive roots). Here, we investigated decomposition of leaf litter and absorptive roots using litter bags for two years across eight temperate and subtropical tree species in China. Results showed that decay rates k (a-1, negative exponential model) were positively correlated between leaf litter and absorptive roots when all eight temperate and subtropical trees were examined in combination, but when tree species were separated by climate zones or growth forms, the correlation was influenced by the soil depth at which leaf litter decomposition occurred, and the type of absorptive roots. N remaining in the leaf and root was not correlated when all eight trees were examined in combination. However, N remaining in the leaf and root was highly and positively correlated between leaf and R1-3 among subtropical trees after one year of decomposition, and between leaf and R1 among temperate trees after two years of decomposition. Here, the correlation between the decomposition of leaf and root was mainly influenced by whether both leaf and root decomposition were controlled by the same or related litter chemistry. In this study, all litter decay rates were positively related to acid soluble C fractions, but negatively related to acid insoluble C fractions. Summarizing results from our study and other studies, we found that the relationship between leaf and root decomposition was largely affected by species. Therefore, species composition dynamics due to climate change would largely affect above-and below-ground relationships and thus ecosystem C cycling.
  • DownLoad:A coordinated decomposition between leaf litter and absorptive roots across eight temperate and subtropical tree species in China.PDF
  • The responses of hydraulic architecture and growth of Quercus aliena to rainfall reduction
  • Authors:CHEN Zhicheng, LU Haibo, LIU Shirong, LIU Xiaojing, LIU Chang and WAN Xianchong
  • Abstract:In recent years, drought has caused increasing forest mortality at a global scale due to climate change, which draws wide attention. The main cause of drought-induced tree mortality is presumed to be out of the carbon-water balance in trees. This study investigated the effects of rainfall reduction on a secondary natural forest of Quercus aliena in Baotianman Mountains by imitating climate change. Three rainfall-intercepted plots were established in situ in a Q. aliena forest in Baotianman Mountain in April 2013, aiming to study the effects of reduced rainfall on the physiological relations of water-carbon, and growth of Q. aliena. The results showed that the predawn and midday water potential values of Q. aliena in the rainfall reduction plots were significantly lower than those of the control trees, and the lowest midday water potential value of rainfall-reduced Q. aliena was (-1.36±0.11)MPa. However, the water potential value which induced the xylem of Q. aliena lost 88% of hydraulic conductance was -3.19MPa, and the water potential value of Q. aliena at stomatal closure was -2.5MPa. Thus, rainfall reduction did not severely disturb the hydraulic architecture of Q. aliena in this region. After reduced rainfall, there were no significant differences in total nonstructural carbohydrates concentrations in leaves, phloem and xylem between rainfall-reduced trees and the control treatment. In summary, the rainfall-reduced Q. aliena trees did not show hydraulic failure or carbon starvation. However, the xylem vessel density and the leaf stomatal density of the rainfall reduction treated Q. aliena were significantly higher than those of control trees, and the xylem vessel diameter and the stomatal length were significantly smaller, which indicated that significant physiological and structural adaptations of rainfall-reduced Q. aliena trees occurred to cope with drought. During the relative drought, rainfall-intercepted Q. aliena showed a bimodal curve of the diurnal variation of stomatal conductance, while the control trees showed a unimodal curve. On the contrary, during the moist period, the diurnal dynamics of stomatal conductance of the rainfall-intercepted Q. aliena trees showed a monopeak curve similar to the control, and the peak value was significantly higher than that of control trees. There were no significant effects of reduced-rainfall on wood density, Huber value, specific leaf area and transversal growth of tree trunk of Q. aliena trees. Our results indicated that rainfall-reduced Q. aliena trees did not show hydraulic failure and carbon starvation, and the growth of Q. aliena was also not significantly influenced by reduced rainfall. However, their hydraulic structure showed adaptive adjustment to cope with more serious drought in future.
  • DownLoad:The responses of hydraulic architecture and growth of Quercus aliena to rainfall reduction.PDF
  • Spatial-temporal dynamics of upland meadow coverage on Wugong Mountain based on TM NDVI
  • Authors:ZHANG Xueling, ZHANG Ying, NIU Dekui, ZHANG Wenyuan, LI Zhi, LI Zhenzhen and GUO Xiaomin
  • Abstract:Taking the upland meadow on Wugong Mountain as a study area, and based on the TM (Thematic Mapper) remote sensing image, this study used ENVI 5.1 and ArcGIS 10.0 software to calculate the vegetation coverage distribution pattern and to analyze the dynamic changes to upland meadow on Wugong Mountain. The results indicated that the area showed a progressively decreasing trend that fell by 9.72% during the study period. During the past 20 years, with the establishment of the Wugong Mountain Scenic Area and the development of tourism, the ecological restoration of upland meadow has meant that vegetation coverage has increased;the vegetation coverage distribution characteristics showed that vegetation was high in the southeast and low in the northwest. The low vegetation coverage meadow area was concentrated on a precipice on the northwest slope and on part of the ridge line, whereas meadow coverage was high on the southeast slope.The degradation and improvement of upland meadow coexisted in the study area. It was degraded in the northernmost end of the upland meadow and the low altitude area of the southeast and south slopes of Bai Hefeng-Jiu Longshan area; the vegetation showed improvement on the southern slope of Fa Yunjie. At the same time, the distribution pattern of vegetation coverage and terrain factors were closely related (P < 0.05):vegetation coverage showed regular change with the change in aspect.Its distribution was in the order:sunny slope > flat area > shady slope.Vegetation coverage rose firstly with the rise of slope and peaked at 15°-25°, but then fell along with the rise of the slope.It reached its lowest value at 45°-90°.Vegetation coverage showed a wavelike decline with increasing altitude, and achieved a maximum value at an altitude of 1000-1200m, and a minimum value at the peak region of 1800-1918.3m. This research showed that the methods employed were feasible and accurate and could be used to investigate large area distributions and variations in mountain meadow coverage. However in order to analyze the evolution and trends on upland meadow more accurately and reliably, the image data for different season should be used in a follow-up study that includes the long-term monitoring of vegetation coverage in the study area.
  • DownLoad:Spatial-temporal dynamics of upland meadow coverage on Wugong Mountain based on TM NDVI.PDF
  • Effects of precipitation control on plant diversity and biomass in a desert region
  • Authors:SUN Yan, HE Mingzhu and WANG Li
  • Abstract:In the context of global climate change, drought and extreme precipitation events will have far-reaching influences on species diversity and productivity of desert plant communities. Studying response mechanisms of plant communities to precipitation fluctuations is of great significance for the scientific management of desert ecosystems. By using rain shelters and drip irrigation systems to control precipitation input, this study evaluated the effects of extreme drought (decreasing precipitation by 50%, D1 treatment), drought (decreasing precipitation by 25%, D2 treatment) and increasing precipitation (increasing precipitation by 50%, W1 treatment; increasing precipitation by 25%, W2 treatment) on species diversity and biomass of desert plant communities. After one-year precipitation control experiments, we found that there was no significant difference in shrub and grass diversity indices, nor shrub biomass, under D1, D2, W1 and W2 treatments. The above-ground biomass of grass layers was sensitive to the precipitation changes. Grass biomass was (10.54±2.36) g/m2 under D1 treatment, in contrast, grass biomass reached (105.69±28.60)g/m2 with 50% precipitation enhancement (W1 treatment). Grass biomass showed a linear increasing trend with precipitation enhancement and was significantly correlated with soil water content of the shallow layer (40cm depth, P < 0.05). Therefore, biomass of grass layers were closely related to short-term (one year) precipitation fluctuations. Based on long-term location experiments, this study will further explore the effects of precipitation change on desert plant community characteristics, the results of which will provide data and theoretical support for response mechanism studies of desert ecosystems against the background of global climate change.
  • DownLoad:Effects of precipitation control on plant diversity and biomass in a desert region.PDF
  • Comparative analysis of burn index adaptability when evaluating grassland fire severity
  • Authors:GONG Dapeng, LI Bingyi and LIU Xiaodong
  • Abstract:The burn index, based on remote sensing images, is widely used to study fire severity. The quantitative evaluation of grassland fire severity by selecting a suitable burn index has great significance when studying vegetation recovery and management. A burnt area of Hulunbuir pasture land was selected as the study area. Landsat8 OLI images were used to develop a regression model of the Composite Burn Index (CBI) using four different burn indices (Normalized Burn Ratio, NBR; NIR-SWIR-Temperature Version1, NSTV1; differenced Normalized Burn Ratio, dNBR; and Relative differenced Normalized Burn Ratio, RdNBR), and the accuracy of the model was tested. The ability to detect fire severity at different levels by the four different burn indices was compared. The results showed that dNBR (n=70, R2=0.856) had the best fitting effect in the polynomial regression model; but there were some differences between the four burn indices when identifying grassland fire intensity at different levels. The NSTV1 index performed best at moderate severity (1 < CBI ≤ 2). For non-fire (CBI=0), low severity (0 < CBI ≤ 1), and high severity (2 < CBI ≤ 3), the dNBR index performed best with accuracies up to 80%, 62.5%, and 100%, respectively; A map of grassland fire severity, which was drawn using the dNBR index, had the highest overall accuracy at up to 82.1%. The Kappa coefficient was also up to 0.76. In conclusion, the dNBR index is the most suitable remote sensing index for analyzing and evaluating grassland fire severity.
  • DownLoad:Comparative analysis of burn index adaptability when evaluating grassland fire severity.PDF
  • Radial growth response of two conifers to temperature and precipitation at upper forest limits in Shika Snow Mountain, Northwestern Yunnan Plateau
  • Authors:ZHANG Yun, YIN Dingcai, SUN Mei, LI Liping, TIAN Kun and ZHANG Weiguo
  • Abstract:The Northwestern Yunnan Plateau, located in the southeastern edge of the Tibet Plateau, is a region sensitive to global climate change. Multiple tree species form the upper treeline on different snow mountains within the region, making the mountains ideal sites for dendrochronological studies. However, climate-growth relationships in the Shika Snow Mountain (one of the typical snow mountains in the region) are unclear, and improved understanding of tree growth response to climate change in Shika is fundamental to predicting growth under future climate change. To detect growth response of multiple species to climate change, we developed residual chronologies of Picea likiangensis and Pinus densata at upper distributional limits in Shika Snow Mountain, Northwestern Yunnan Plateau, using dendrochronology. We used response function to study relationships between residual chronologies and climatic factors, aiming to elucidate the main climatic factors affecting radial growth of conifers in the Northwestern Yunnan Plateau. To further analyze and verify the relationships between radial growth and temperature and precipitation, redundancy analysis was applied. Results showed that temperature was the main factor influencing conifer growth at the upper forest limits in the Shika Snow Mountain; temperature and precipitation have a lag effect on tree radial growth and the two conifers responded differently to climatic factors. Specifically:(1) The radial growth of P. likiangensis was affected by temperature and precipitation, showing a significantly negative correlation with mean minimum temperature of the previous October, and a significantly positive correlation with mean maximum temperature of the previous November and temperature of the current July. Precipitation of the previous August and current May inhibited growth of P. likiangensis. (2) The radial growth of P. densata was significantly and positively correlated with mean temperature and maximum temperature of the previous October and mean temperature of the previous November, and showed a significantly negative correlation with mean temperature and maximum temperature of the current July. However, no significant correlation was detected between growth and precipitation. (3) The redundancy analysis presented similar results as the response function analysis, further indicating that the method can effectively quantify the relationship between tree radial growth and climatic factors. This study provides a theoretical basis for the management and protection of forest ecosystems in the Northwestern Yunnan Plateau faced with climate change.
  • DownLoad:Radial growth response of two conifers to temperature and precipitation at upper forest limits in Shika Snow Mountain, Northwestern Yunnan Plateau.PDF
  • Correlations between landscape pattern and plant diversity at multiple spatial scales: a case study of Hunshandak Sandland
  • Authors:FAN Min, PENG Yu, WANG Qinghui, MI Kai and QING Fengting
  • Abstract:Landscape pattern is one of the important factors affecting plant diversity. However, the effect of landscape pattern in sandy areas remains unclear at various spatial scales. To investigate correlations between landscape pattern and plant diversity, as well as their scale dependence, the present study used field surveys and remote sensing technology to establish plant diversity indices and landscape metrics for the Hunshandak Sandland, northern China. Correlations among alpha diversity, beta diversity, and 33 landscape metrics were screened using bivariate correlation analysis at ten spatial scales (100, 200, 300, 400 500, 600, 700, 800, 900, and 1000m), and significant models were selected by stepwise regression analysis and verified by comparing fitted and field values. We found that landscape metrics influenced plant diversity in a scale-dependent manner The landscape pattern indices had a greater influence on Shannon diversity and β diversity than other diversity indices. The R2 (0.138) of the Shannon diversity by stepwise regression was highest at the 100m scale, whereas the R2 (0.2) of those of β diversity by stepwise regression was highest at the 900m scale. Comparison of the fitted and field values indicated that the Pielou, Shannon, and Whittaker indices were significant at the 500m scale, which confirmed that landscape pattern metrics significantly influence pant diversity at the 500m scale in sandy grassland. This demonstrates the importance of considering the scale effects of landscape pattern during plant diversity conservation and indicates that landscape pattern should be optimized and maintained in order to manage and preserve plant diversity in sandy grassland communities.
  • DownLoad:Correlations between landscape pattern and plant diversity at multiple spatial scales: a case study of Hunshandak Sandland.PDF
  • An analysis of temporal dynamics of litter-layer beetles in broad-leaved Korean pine forest in Jiaohe, Jilin Province
  • Authors:LIU Shengdong, MENG Qingfan, GAO Wentao, LI Yan, ZHAO Hongrui and LI Tianqi
  • Abstract:Broad-leaved Korean pine forest is a typical zonal forest community in the eastern forest area of China, with high biodiversity. The temporal dynamics of the diversity of litter-layer beetles was investigated in broad-leaved Korean pine forest in Jiaohe, Jilin Province, and the responses of dominant groups were compared in different times, in order to provide scientific basis for the protection and utilization of litter-layer beetles in forests. Litter-layer beetles were collected by pitfall traps in adult beetles entire active period from mid May to late August during 2012 to 2013 at 4 sampling plots in the broad-leaved Korean pine forest. In total, 9849 specimens were collected, belonging to 22 families and 79 species, among which Carabidae, Silphidae, and Staphylinidae were the dominant groups. The species number, individual number and diversity index of litter-layer beetles were the highest in early July, and time had a significant impact on the number of individuals (P < 0.05). There was a low correlation among each index of litter-layer beetles, some species were more sensitive to environmental changes. The individual number of Carabidae in early July was significantly higher than during other times, and temporal dynamics of species number and individual number were not accordant. Additionally, the adaptability of Carabidae was higher than that of Silphidae and Staphylinidae in August. The individual number of Silphidae in early July was significantly higher than at other times (P < 0.01), and the temporal dynamics of species number and individual number were consistent. The adaptability of Silphidae was higher than that of Staphylinidae in July. The response of Silphidae to time change was the most sensitive, and their individual number could increase rapidly when the environmental conditions were appropriate. The variation of species and individual number of Staphylinidae was relatively small at different times, and the sensitivity of Staphylinidae to time change was the lowest. Because of the special life habits, the activity peak of predatism and saprophagous litter-layer beetles may be linked to the number of prey insects during every period.
  • DownLoad:An analysis of temporal dynamics of litter-layer beetles in broad-leaved Korean pine forest in Jiaohe, Jilin Province.PDF
  • Population structure and dynamic characteristics of endangered Syringa pinnatifolia Hemsl.
  • Authors:JIANG Zaimin, HE Zisen, SU Hao, ZHAO Han and CAI Jing
  • Abstract:Syringa pinnatifolia Hemsl. is a unique rare and endangered species in China. In this study, surveys on the natural population of S. pinnatifolia in the Gangou Preserve in the Helan Mountain and Xiangshan in Zhongwei city were conducted for the first time. Characteristics of population structure were described by establishing a static life table and drawing a population survival curve. Their future development trends were researched quantificationally by population dynamic prediction and time series analysis. The results showed that the Xiangshan population fit the growing type, and the Helan Mountain population fit the declining type. Both populations were sensitive to external interference. The population development of S. pinnatifolia was primarily maintained by middle-and old-aged individuals, with a lack of seedlings to different degrees. The population survival curves tended to be the Deevey-Ⅱ type. Mortality and risk curves both showed that the mortality at each age level rose in a fluctuating manner as age increased, and the range of fluctuation in the Xiangshan population was the most significant. Survival analysis also showed that Xiangshan population entered the decline phase earlier than the Helan Mountain population. Combined with the habitat conditions, the Helan Mountain region was more suitable for the survival of S. pinnatifolia. Dynamic indexes and the results of time series analyses indicated that the population of S. pinnatifolia had the following dynamic characteristics:early stage, declining; middle stage, stability; and late stage, recession. The lack of young individuals was one of the main reasons for its endangerment. Consequently, suggestions are put forward based on the closure of hillsides to facilitate afforestation, the strengthening of research on highly efficient breeding technology of S. pinnatifolia, and the implantation of artificial rearing measures to ensure the normal development of its population.
  • DownLoad:Population structure and dynamic characteristics of endangered Syringa pinnatifolia Hemsl..PDF
  • Characteristics of population structure and community species diversity of an extremely small population of protected Phyllitis scolopendrium
  • Authors:HUANG Xiangtong, YIN Hang, HUANG Qijian, CUI Kaifeng, ZHAO Ying, JIN Hui, LIU Qibin and DUAN Hongjun
  • Abstract:For Phyllitis scolopendrium, a second-class national protected wild plant with extremely small populations, which is distributed in a narrow region of the Changbai Mountains, we analyzed the population size, distribution frequency and density, individual features, and the variation of internal and external populations at 729 and 1008m above sea level (asl). The plant height, substitute age structure, distribution pattern, community biodiversity, and similarity of various layers were also described. Results showed that P. scolopendrium was a typical occasional species, which showed a patchy distribution pattern. At 729m asl, the population density was the highest (91 per 400m2), with a distribution frequency of 93.75% and highest density of 30/25m2. At 1008m asl, the population density was only 31 per 400m2, with a distribution frequency of 43.75% and highest density of 15/25m2. Based on the analyses of morphological features, including plant height, leaf number, sporangium leaf number, maximum leaf length and width, minimum leaf length and width, canopy width, and leaf thickness, we found that the morphological features of the internal population showed the highest variation, indicating a decreasing trend with increasing height/age. Additionally, variations in plant height, mature sporangium leaf number, maximum leaf length and width, canopy width, and leaf thickness all showed significant differences (P < 0.01), indicating that the two populations were from different species types. Plant height showed a double peak pattern. Trough value of type 01 population occurred at 15.1-20.0cm, whereas the trough value of the type 02 population occurred at 10.1-15.0cm. There was a significant update process in both types, and a break of the type 01 population at 40.1-45.0cm. We analyzed the age structure of type 01 and 02 populations and found that there were five age classes of the type 01 population, which showed a normal distribution pattern, whereas the type 02 population had four age classes, which showed an inverted J distribution pattern. Type 01 and 02 populations were at juvenile and middle age stages, with no trend of senescence. Based on the spatial pattern analysis, we found that P. scolopendrium showed a negative binomial distribution pattern. The diversity indices, including Shannon-Wiener, Pielou, and Margalef, showed that the similarity index of tree, shrub, and herb layers in the two types was low, indicating a low biodiversity status compared with the local climax community. Phyllitis scolopendrium was considered a companion species because of lower importance value in type 01 and 02 communities. Similarity analyses showed that plants in tree and shrub layers were the most similar, followed by the herb layer with values of 66.67%, 69.23%, and 38.46% respectively, indicating that the herb layer had the most variation.
  • DownLoad:Characteristics of population structure and community species diversity of an extremely small population of protected Phyllitis scolopendrium.PDF
  • Photosynthetic characteristics differ between emergent and floating-leaved macrophytes
  • Authors:XIE Chun, ZHOU Changfang, LONG Shuiyun, WANG Wenlin, XIA Qindong, PINGCUO Sangzhu and XU Zixuan
  • Abstract:Emergent and floating-leaved macrophytes, two different life forms of primary producers in shallow lakes and riparian zones, play important roles in nutrient cycling and energy flow of aquatic ecosystems. To investigate the differences in photosynthetic characteristics between the two forms of macrophytes, chlorophyll fluorescence, pigment composition, and special leaf weight (SLW) of four emergent macrophytes (Acorus calamus L., Pontederia cordata L., Thalia dealbata Fraser, Zizania latifolia (Griseb.) Stapf) and four floating-leaved macrophytes (Nymphaea mexicana Zucc., Brasenia schreberi J. F. Gmel., Nymphoides indica (L.) O. Kuntze, Trapa bispinosa Roxb.) growing in natural habitats were compared. In general, emergent macrophytes showed higher electron transport rate (ETR) and non-photochemical quenching (NPQ) under high irradiation, as well as relatively higher initial slope (α) of ETR curve under low light, than did floating-leaved plants. Broader ranges on maximum quantum yield of PSⅡ (Fv/Fm), ETR, NPQ, maximum potential ETR (Ps), maximum ETR (ETRm) and saturating irradiance (Em) were also found among different species of emergent macrophytes. Average chlorophyll (Chls) and carotenoid (Cars) contents were also higher in emergent macrophytes than in floating-leaved ones. However, due to the discrepancy of SLW, the trends of pigment amount among species on a fresh matter basis differed from those per leaf area unit. Among the four emergent macrophytes, T. dealbata and P. cordata exhibited relatively higher photosynthetic ability, and all fluorescence parameters together with pigment ratios (Chl a/b, Chls/Cars) indicated they belonged to the sun type. However, A. calamus and Z. latifolia exhibited relatively lower photosynthetic ability, and part of the parameters were closer to the shade type. All four floating-leaved species exhibited as sun type. This suggests that the heterogeneity of environments contributes to the discrepancy of leaf photosynthetic abilities. Emergent leaves grow in highly diverse environments, so their photosynthetic parameters have broad ranges, whereas the environments for floating leaves are relatively stable, so their parameters are limited to small ranges. It may not be necessary for floating-leaved macrophytes to develop NPQ and internal heat dissipation to prevent high irradiation damage. In conclusion, special attention should be paid to both environmental heterogeneity and discrepancy of adaptation abilities when selecting aquatic macrophytes for wetland restoration.
  • DownLoad:Photosynthetic characteristics differ between emergent and floating-leaved macrophytes.PDF
  • Dynamic evaluation of ecological security and its driving factors in the process of urbanization of islands: a case study of Pingtan Island
  • Authors:GAO Sheng, CAO Guangxi, HONG Tao, ZHAO Lin and XU Min
  • Abstract:With the acceleration of the urbanization process of islands, the contradiction between the development and construction of islands and the ecological safety has become increasingly prominent. It is of great significance to promote the coordinated development of the social, economic, and ecological environment of Pingtan Island by objectively evaluating the dynamic changes and the driving forces of the ecological conditions in the development and construction of Pingtan Island. We selected 2001 as the ecological security status evaluation benchmark year. In addition, natural and socio-economic indexes from 2005 to 2015 were selected to construct the Driving forces-Pressure-State-Impact-Responses (SPSIR) evaluation index system for ecological security assessment of Pingtan Island. Using the comprehensive index method, it was observed that the driving factors and impact factors were relatively stable in the evaluation years. The dynamic trends of the pressure and state factors were similar. The dynamic changes in the response factors were relatively stable before the establishment of the comprehensive test area in 2009, but the fluctuation was most obvious from 2009 to 2012. Response factors, pressure factors, and state factors have a significant impact on the ecological security index. Response factors, taken together, was the key factor impacting ecological security index. The ecological security status of Pingtan Island is on the rise, but the ecological security situation was relatively stable in 2001 and 2005 to 2009. Since the establishment of the comprehensive experimentation area, the ecological security index has risen the maximum, especially during the period from 2009 to 2011. From 2011, the ecological security index reached 0.7612, which was a good threshold compared to the ecological security situation of 2010 and then showed a slight decline at a smooth state from 2012 to 2015. Correlation coefficients between the state index, driving force index, response index, and safety index were higher, and the response index was greater than the correlation coefficient of the pressure index. Through principal component analysis and path analysis, it was found that the principal component scores in 2011 and 2015 were the highest, with 1.5277 and 1.1974, respectively. The response factors play a crucial role in the ecological security of Pingtan Island. Among these, Transportation investment ratio, Health and social security investment ratio, Public facility investment ratiohave direct and indirect impacts on the ecological security of Pingtan Island. These results support the empirical case and relevance of the theoretical system of island environmental assessment, and provide a reference for the ecological security assessment of the domestic island urbanization process.
  • DownLoad:Dynamic evaluation of ecological security and its driving factors in the process of urbanization of islands: a case study of Pingtan Island.PDF
  • Standard of payment for ecosystem services in a watershed based on InVEST model under different standpoints: a case study of the Weihe River in Gansu Province
  • Authors:WU Na, SONG Xiaoyu, KANG Wenhui, DENG Xiaohong, HU Xiangquan, SHI Peiji and LIU Yuqing
  • Abstract:Standard of payment is the core content of a payment for ecosystem services (PES) project. Considering the conversion of farmland to a variety of forestlands, based on the definition of the PES standard range, we calculated the increments of ecosystem services in the Weihe River Basin in Gansu Province with the InVEST model and the weighted method, using the land use, meteorological, soil, socioeconomic, and questionnaire survey data, to improve operability of the payment standard. The difference between forestland and farmland in ecosystem services was used to characterize the main increments of ecosystem services of water yield, sediment retention, and water purification. The number of ecosystem services for forestland came from the weighted sum of weights (the ratio of each kind of converted forest area accounted for the total conversion area) and the number of ecosystem services per unit area of corresponding forest. Additionally, setting the increased value of ecosystem services as the payment upper limit and taking the opportunity cost of participators as the lower limit, the differentiated PES standard of returning farmland to forest in 15°-25° and above 25° sloping farmland were studied from the standpoint of a new round of national policy oriented towards returning farmland to forest. Furthermore, from the standpoint of fair distribution of benefits, the differentiated PES standard in different net income regions, coupled with opportunity cost input and ecosystem services output, were explored. The results showed that the PES standard of returning farmland to forest was range from 146.39×104 Yuan km-2 a-1 to 481.98×104 Yuan km-2 a-1 in the Weihe River Basin of Gansu Province. With returning farmland to forest, the annual value of water yield would increase by 1.49×104 Yuan/km2; the annual value of sediment retention would increase by 479.55×104 Yuan/km2; and the annual value of water purification would increase by 0.94×104 Yuan/km2. Secondly, the results showed that the areas in sloping farmland (15°-25°), which were the upstream faces of important drinking water sources in first-level protected and reserved areas, accounted for approximately 10% of the sloping farmland. If all above-mentioned areas in sloping farmland (15°-25°) changed to the forestland, PES funds of 13.95×108 Yuan to 33.55×108 Yuan would be needed. For those above 25°, PES funds ranging 12.96×108 Yuan to 28.35×108 Yuan would be needed. For the areas in sloping farmland (15°-25°), the increased annual values of water yield, sediment retention, and water purification were 13.35×104, 337.42×104, and 0.81×104 Yuan/km2, respectively. Values for the areas above 25° were 15.99×104, 302.90×104, and 0.76×104 Yuan/km2, respectively. The ranges of PES for the areas in sloping farmland (15°-25° and above 25°) were 146.39×104 to 351.58×104 Yuan km-2 a-1 and 146.39×104 to 319.65×104 Yuan km-2 a-1. Finally, compared with other districts, the maximum net income of returning farmland to forest appeared in the Maiji district, and the minimum was represented in the Longxi district. Their ranges of PES were 202.23×104 to 727.92×104 Yuan km-2 a-1 and 96.99×104 to 136.53×104 Yuan km-2 a-1, respectively.
  • DownLoad:Standard of payment for ecosystem services in a watershed based on InVEST model under different standpoints: a case study of the Weihe River in Gansu Province.PDF
  • The evolution rules and the driving mechanisms behind rural settlement in the peak-cluster depressions of Guizhou Province, China, over the past 50 years
  • Authors:LI Yangbing, LI Ruikang, LUO Guangjie, XIE Jing and XU Qian
  • Abstract:It is important to identify the regional differences of the evolution model and the functional transformation of rural settlement driven by various influenced factors. This study explores the evolution model, the internal mechanism, and their regional differences of rural settlement driven by multiple backgrounds in typical peak-cluster depressions under different natural and social economic conditions over the past 50 years, especially the last 10 years. This was achieved by using high resolution remote sensing data from a long time series. The research result are as follows:(1)the distribution of rural settlement is influenced by the cropland, terrain, and roads, and there are regional differences in the coupling relationship between the increased areas of rural settlement hotspots and increased rural settlement patches; (2) there are agglomeration and uniform distribution trends in the evolution of the rural settlement pattern; (3) the regional differences of rural settlement characteristics and evolution stages in the study area are very clear; (4) the scale change, evolution stage, and evolution model of rural settlements in peak-cluster depression areas have some common features and some individual differences; and (5) the main driving forces behind evolution are the external factors and self-adjustment by the settlement farmers.
  • DownLoad:The evolution rules and the driving mechanisms behind rural settlement in the peak-cluster depressions of Guizhou Province, China, over the past 50 years.PDF
  • Influence of human factors on the economic productivity of grey water in China
  • Authors:BAI Tianjiao, SUN Caizhi and ZHAO Liangshi
  • Abstract:There is an urgent need for solutions to enable the sustainable development of the water resource environment and economy in China. The present study investigated the economic productivity of grey water (EPGW), which was defined as the ratio of gross domestic product to grey water footprint. Based on an analysis of regional characteristics and spatial correlation of the EPGW in the 31 provinces, cities and autonomous regions in China (the data of Hongkong and Macao special administrative regions and Taiwan Province have not been counted) from 2000 to 2014, we used the spatial Durbin model to examine the relationship between human factors and the EPGW. We found that the EPGW in China increased over time and that the nationwide productivity increased from 19.85 yuan/m3 in 2000 to 107.93 yuan/m3 in 2014, and the 15-year average EPGW was 52.19 yuan/m3. In the eastern region, the EPGW was significantly higher than that of the central and western regions and was lowest in the western region. The difference in average productivity, over 15 years, between the eastern region and the central and western regions was > 50 yuan/m3. From 2000 to 2014, the EPGW in China exhibited a significant positive auto-correlation in regards to spatial distribution, and the spatial agglomeration degree was higher and not randomly distributed. In recent years, however, interregional differentiation in the EPGW has intensified. From the national perspective, the optimization of industrial structure, urbanization, and social welfare are conducive to the growth of the EPGW in local regions. Therefore, improving the level of education and social welfare has positively affected the EPGW in other areas. Improving education, urbanization, social welfare, and the proportion of tertiary industry could positively impact the EPGW of the eastern region. And improving education could also have a significant positive impact on the EPGW of the eastern region's outer area. Reducing social welfare in the central region has positively affected the EPGW of the adjoining and surrounding areas. The total effect coefficient of urbanization reached 4.8446 in the western region, and improving social welfare positively affected the EPGW of the western region's outer area. In addition, various regions need to reduce the disparity between the EPGW of urban and rural areas, improve the GDP of rural areas, and promote a healthy development in both economy and environment. On the basis of these observations, we propose various suggestions that could further promote the coordinated development of water environment and economy in China.
  • DownLoad:Influence of human factors on the economic productivity of grey water in China.PDF
  • Climate effects on NDVI change of upland meadow in Dahaituo Nature Reserve over 30 years
  • Authors:SONG Chao, YU Qiyin, XING Shaohua, WU Zhanjun, LI Yongxia, REN Zhihe and LIU Yongsheng
  • Abstract:Hebei Dahaituo Nature Reserve is located in a warm, temperate, deciduous broad-leaved forest area in China. Meadow vegetation, which are sensitive to outside interference, are mainly distributed on top of Dahaituo Mountain. To determine the change and response of vegetation to climate change in the Dahaituo Nature Reserve and surrounding area, we collected a series of data, including Thematic Mapper(TM) remote sensing image data for the last 30 years and climate data from 1980 to 2015, including annual average temperature, average temperature in July, average temperature in January, annual precipitation, average precipitation in June to August, and terrain data. We analysed the relationship between the change in the meadow vegetation Normalized Difference Vegetation Index (NDVI) and climate change using the moving average method, the M-K method, correlational analyses, and partial correlation analyses. The results showed that:(1) NDVI of the meadow vegetation in Dahaituo Nature Reserve showed a downward trend in the past 30 years, after rising, achieved the best growth conditions in 2003, then gradually decreased. (2) The change in annual precipitation varied, but generally increased slightly. Annual average temperature showed a significant upward trend, with the temperature rise mainly caused by increased winter (January) temperatures. (3) NDVI of the meadow vegetation and average annual temperature were negatively correlated, whereas NDVI of the meadow vegetation and annual precipitation tended to be positively associated.
  • DownLoad:Climate effects on NDVI change of upland meadow in Dahaituo Nature Reserve over 30 years.PDF
  • Analysis of current situation and assessment of spatial layout of nature reserves in the Tibet Autonomous Region
  • Authors:LI Shicheng, LI Shaowei, XINA Ji, CIRENLUOBU, YANG Zhen, DENG Yujie and SUN Wei
  • Abstract:Assessment of the spatial layout of nature reserves can provide scientific basis for policy-makers. Most previous studies concerning nature reserves in the Tibet Autonomous Region only focused on a single nature reserve, and almost no studies have paid attention to the layout of all nature reserves in the Tibet Autonomous Region. In this study, on the basis of national nature reserves list data and employing classification, time series analysis, and spatial overlapping methods, we analyzed the current situation and spatial-temporal changes of nature reserves in the Tibet Autonomous Region and assessed the rationality of their spatial layout from the perspectives of human and nature dimensions. The results suggest that:(1) At the end of the year 2015, there were 47 nature reserves in the Tibet Autonomous Region with an area of 413.7×103 km2, ranking the first place in China. Fragile ecosystems and national key protected plants and animals in the Tibet Autonomous Region were mostly covered by national and provincial nature reserves. (2) Before the year 2000, the spatial patterns of newly established nature reserves during 1990-2015 expanded from the southeastern Tibet Autonomous Region to the mid-western Tibet Autonomous Region; after 2000, more newly established nature reserves appeared in the central of the Tibet Autonomous Region. The spatial layout of nature reserves is becoming more rational. (3) From the perspective of the human dimension, the mean human influence intensity of the total nature reserves is about half of that of the Tibet Autonomous Region, indicating that the contradiction between ecological protection and human activities is not serious in terms of the spatial layout of nature reserves. For several nature reserves whose human influence intensity is greater than the average value, their spatial layout can be optimized. (4) From the perspective of the nature dimension, the densities of nature reserves in each eco-geographic region or vegetation zone are close, but the percentages of nature reserve areas in each eco-geographic region or vegetation zone are obviously different, which means that the spatial layout can be optimized further.
  • DownLoad:Analysis of current situation and assessment of spatial layout of nature reserves in the Tibet Autonomous Region.PDF
  • Differences in responses of macroinvertebrate traits and functional diversity to environmental variables at different spatial scales between ecoregions in the Wei River basin, China
  • Authors:LI Shengli, YI Maohong, CHEN Kai, DING Ning, WANG Beixin and YAO Huarong
  • Abstract:Using the macroinvertebrates collected from mountain and lowland ecoregions in the southern basin of Wei River as indicators, we compared the differences in the composition of 29 macroinvertebrate trait categories and seven traits and functional diversity indices between the two ecoregions. The combination of the joint analysis of R (environmental×sites), L (species×sites), and Q (trait×species) (RLQ) and fourth-corner analysis methods was conducted to explore the relationships between macroinvertebrate trait composition and land use and physical and chemical variables. We then used a generalized linear model (GLM) to compare differences in the responses of macroinvertebrate traits and functional diversity to environmental variables at different spatial scales between the two ecoregions. Our results showed that 18 of the 29 biological traits and 6 of the 7 traits and functional diversity indices significantly differed between the two ecoregions. Macroinvertebrates with biological traits such as none and shelters of leaf parts or wood refuge, lightly sclerotized, well protected exoskeleton or external protection, herbivores, and predators preferred habitats in the mountain ecoregion, while biological traits with integumentary respiration, soft body, and collector-gatherers tended to frequently occur in the lowland ecoregion under higher intensity of human activities. All traits and functional diversity indices, except functional evenness, were significantly higher in the mountain ecoregion than in the lowland ecoregion, which demonstrated that environmental stressors significantly decreased the biological traits and functional diversity in lowland areas. The combination of RLQ and fourth-corner methods revealed that the traits demonstrated a predictable response of trait patterns along the environmental gradient. The GLM model predicted that the functional and trait diversity in mountain and lowland ecoregions could be explained by different environmental variables at different spatial scales, with catchment urban land use, water temperature, and total nitrogen explaining most variations within the biological traits and functional diversity in the mountain ecoregion; but with reach scale agriculture land use and average water depth mainly explaining the decrease of the functional diversity in the lowland ecoregion.
  • DownLoad:Differences in responses of macroinvertebrate traits and functional diversity to environmental variables at different spatial scales between ecoregions in the Wei River basin, China.PDF
  • Evaluation of non-use value and analysis of influence factors affecting Crossoptilon mantchuricum in China
  • Authors:ZHANG Yinbo, LIU Yingli, DU Leshan and WANG Wenzhi
  • Abstract:The economic value assessment of wild species is key to conservation biology, and is the theoretical basis of species conservation, ecological compensation, and the economics of ecosystems and biodiversity (TEEB) action plan. This research used the contingent valuation method (CVM) to evaluate the non-use value of an endemic threatened bird Crossoptilon mantchuricum. The results showed that 503 effective questionnaires were completed, in which willingness to pay (WTP) accounted for 70.97% of the responses. The average individual WTP for Crossoptilon mantchuricum was 28.39-36.88 yuan/a, and the total non-use value ranged from 21.89×109 to 28.44×109 yuan/a. The Logit model estimate of the factors influencing WTP suggested that cognition degree, number of times respondents have seen Crossoptilon mantchuricum, the education and income levels positively affected WTP, and that cognition degree had the greatest effect. However, the age of the respondents negatively affected WTP. After comparing the domestic valuations of the species, the scope of the assessment, the WTP unit, and the total sample setting were also considered to be factors that can directly influence the final result of the species valuation.
  • DownLoad:Evaluation of non-use value and analysis of influence factors affecting Crossoptilon mantchuricum in China.PDF
  • Review of development, frontiers and prospects of wetlands eco-hydrological models
  • Authors:WU Yanfeng and ZHANG Guangxin
  • Abstract:The variability of eco-hydrological condition caused by climate change and human activities exerted a significant detrimental influence on water and ecological security in watershed region and national scale. The eco-hydrological model is an important and efficient tool for revealing interactive mechanism between ecological processes and hydrological processes. This paper reviews concept, connotation, construction methodologies and classification as well as domestic and international development of eco-hydrological models, then focuses on the key fields in the studies:ecological regulation and water resources management in wetlands, wetlands restoration and conservation and adaptive water resources management for watershed scale as well as evaluation of eco-hydrological variability under the condition of climate change and corresponding mitigation measures. Considering the problems and weakness in studies, we proposed the development trends of future research and key problems to be solved in wetland eco-hydrological models.
  • DownLoad:Review of development, frontiers and prospects of wetlands eco-hydrological models.PDF
  • The key scientific issues and thinking on the construction of “Sponge City”
  • Authors:LI Lan and LI Feng
  • Abstract:"Sponge City" has emerged as a hot scientific and governmental research topic given its ability to effectively control disasters resulting from urban storm water and flooding. "Sponge City" not only supplies groundwater and addresses water shortages but also improves urban water environments, biodiversity, and urban landscapes, all of which contribute to the development of an urban economy and society. Accordingly, "Sponge City" has become a principal force in the new generation of urban construction projects. The scientific construction of a "Sponge City" has become especially important in light of the recent urban flooding in the country. This paper summarizes the background, concept, and connotation of "Sponge City" construction, its relationship with ecological infrastructure, its construction route, and its main technology. We identified several key scientific issues and a construction perspective for "Sponge City" based on four aspects, including improving the ecosystem services of "Sponge City," identifying valuation indicators and establishing a management system, and promoting awareness. This paper identified issues related to the construction of "Sponge City" and examines how its contents must be improved in the future. We also advanced the overall framework of "SPONGE," which includes service, participation, organization, natural ecology, green infrastructure, and ecological pattern. The key contents and vital parts of a "Sponge City" are generalized from this framework, which is expected to provide important materials for further research on this topic.
  • DownLoad:The key scientific issues and thinking on the construction of “Sponge City”.PDF

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