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Volume 39,Issue 11
  • An overview of forest carbon measurement methods
  • Authors:ZHAO Miaomiao, ZHAO Na, LIU Yu, YANG Jilin, LIU Yi and YUE Tianxiang
  • Abstract:Forests are the main body of terrestrial ecosystems; they are not only huge carbon stocks, but also have a positive effect on mitigating climate warming. Effective scientific forest carbon inventory measurement methods help to elucidate the global carbon cycle. Generally, however, due to the complex structure of forest ecosystems, the estimation of forest carbon measurements has had problems of low accuracy and high uncertainty. In recent years, a large number of methods for estimating forest carbon have been developed domestically and overseas. These methods mainly include forest vegetation and soil carbon estimation methods based on the inventory of sample plots, growth harvesting-based empirical model estimation and remote sensing estimation based on quantitative remote sensing and radar observations data, flux observations based on multi-scale forest ecosystem networks, and numerical simulation based on terrestrial ecosystem process models. In actual forest carbon measurement, different (or even multiple) carbon measurement methods are often used depending on the characteristics of different forest types and data acquisition. From the main methods of ecological process model simulation, remote sensing inversion, and data assimilation techniques, and based on multi-source data from carbon flux observation, a control experiment and remote sensing, multi-disciplinary, multi-process, and multi-scale integrated network observations have been developed to fully understand the spatial and temporal distribution characteristics of carbon sources and sinks in the cycle process. Systematic and integrated studies on carbon cycles have been carried out at regional, continental, and global scales, and their response to global changes and human activities, in order to establish an efficient and reliable carbon measurement system. These research aspects will be the development trend of forestry carbon measurements in the future. With the preparation of greenhouse gas emission inventories in various countries, China urgently needs a scientific method system to measure forest carbon sources and sinks in order to increase their international voice and dominance in ecological and environmental issues, and provide suggestions and support for sustainable forest management and ecological and environmental protection. This paper analyzes the main characteristics, advantages, and disadvantages of various forest carbon measurement methods, and discusses existing problems and the future development trend in forest carbon measurement methods, providing reference for forest carbon measurements under different spatial and temporal scales.
  • DownLoad:An overview of forest carbon measurement methods.PDF
  • Influence of Moso bamboo invasion on forest plants and soil: a review
  • Authors:TONG Ran, ZHOU Benzhi, JIANG Lina, CAO Yonghui, GE Xiaogai and YANG Zhenya
  • Abstract:The stability and dynamic changes in plants and soil reflect the self-regulation and adaptability of forest ecosystems in complex habitats. The influence of Moso bamboo invasion on forest ecosystems has become a new research focus. This article reviewed the invasion mechanisms of Moso bamboo, and the influence of Moso bamboo invasion on forest plant viability, species diversity, vegetation carbon storage, soil physical and chemical properties, and the structure and function of soil microorganisms. Aimed at the problems existing in current research, we suggested that research should focus on enhancing the means of controlling Moso bamboo invasion, concentrating on the long-term monitoring of succession between different types of bamboo and forest interface, defining the stages of Moso bamboo invasion, and strengthening the study on the ecological effect after Moso bamboo invasion. This article is helpful to understand the interaction between the forest and Moso bamboo invasion, and forest response and adaptation to Moso bamboo invasion. It can be used as a reference to understand Moso bamboo invasion mechanisms, and predict the changing characteristics of plants and soil after Moso bamboo invasion.
  • DownLoad:Influence of Moso bamboo invasion on forest plants and soil: a review.PDF
  • Temporal and spatial patterns of phytoplankton species richness in the Pearl River Delta
  • Authors:JIA Huijuan, LAI Zini and WANG Chao
  • Abstract:The Pearl River Delta is the most economically active and densely populated region in South China. The production of domestic and industrial waste has increased considerably because of this economic development, and a 10% increase in waste production is estimated to have occurred in the past few years. The spatio-temporal patterns of phytoplankton species richness of the Pearl River Delta in 2012 were demonstrated in this study, based on data from 13 representative sampling sites covering most of the area of the river delta. During the investigation, 383 species from 7 groups were identified. The main groups were diatoms (Bacillariophyceae) and chlorophytes, accounting for 41.78% and 29.24% of the total numbers, respectively. Euglenophyta and Cyanobacteria were subsidiary groups. Physical and chemical variables were analyzed to assess key factors and their interaction mechanisms were demonstrated using redundancy analysis. The total species richness was significantly different among the stations in dry seasons, but not in wet seasons. In dry seasons, river water disturbance caused the suspension of diatoms. In wet seasons, exogenous supplementation occurred and the river became diluted, thereby causing a reduction in diatoms. The total species richness of the stations around Guangzhou and of several stations around the middle of the delta was higher than that of the other stations, which was mainly related to the spatial pattern of nutrient levels and the water exchange capacity. The spatial characteristics of different seasons showed that the species richness in dry seasons increased along the West River, the middle of the delta, and the area surrounding Guangzhou, indicating that nutrient contents were the most important factor. In contrast, in the wet seasons, the species richness on both sides of the delta was higher than that in the middle of the delta. This was influenced by water flow replenishment and water exchange capacity. Moreover, the proportional composition of various groups showed that diatoms accounted for the highest proportion of total phytoplankton species in the dry season, decreasing in the wet season. The proportion of diatoms decreased during floods, owing to the supplementation of chlorophytes, euglenophytes, and cyanobacteria through influx into the main river channel from dead zones. The percentage of diatoms in the Guangzhou station was significantly lower than that of the other stations. This was primarily because the Guangzhou station was located at the intersection of rivers, and there was algal supplementation by external rivers all year round, and secondly because the Guangzhou station was located in the center of the city. These areas have large water discharges, resulting in higher nutrient contents than other areas. On the basis of statistical analysis, we concluded that neutralization of exogenous supplementation and dilution of the river and the suspension of diatoms caused by river agitation not only affected the seasonal variations of species richness, but also the relative composition of different groups. The water exchange capacity and nutrient contents were the key factors determining the spatial distribution of species richness in the wet and dry seasons, respectively.
  • DownLoad:Temporal and spatial patterns of phytoplankton species richness in the Pearl River Delta.PDF
  • Niche and interspecific association of major nekton in the Hui-bie-yang sea area of Hangzhou Bay
  • Authors:LIU Hui, YU Cungen, ZHENG Ji, DENG Xiaoyan, ZHANG Ping, YAN Wenchao and XIE Xu
  • Abstract:Based on fishery survey data from the Hui-bie-yang sea area of Hangzhou Bay in the autumns of 2015 and 2017, the ecological relationship between major nekton was analyzed via niche breadth, niche overlap, cluster analysis, W-test, χ2-test, association coefficient (AC), and percentage of co-occurrence (PC). The results showed that there were 21 major nekton species in this area; of which, the dominant species were Harpodon nehereus and Exopalaemon annandalei, whose niche widths occupied the top two. Based on the niche breadth cluster analysis, the major nekton species were divided into three groups:wide niche breadth species, moderate niche breadth, and narrow niche breadth species. The niche overlap values varied from 0-0.93, which shows marked difference, indicating that the species had a similarity of ability in using resources, and there was a certain degree of competition between species. The VR and W results showed that the major nekton species were significantly positively correlated. The χ2-test suggested that there were significantly interspecific associations for 105 species pairs (χ2 ≥ 3.841). The results of AC and PC revealed that the association of interspecificity was strong, and tended to be positive correlation.
  • DownLoad:Niche and interspecific association of major nekton in the Hui-bie-yang sea area of Hangzhou Bay.PDF
  • Dynamic evaluation of grassland ecosystem services in Xilingol League
  • Authors:LOU Peiqing, FU Bolin, LIU Haixin, GAO Ertao, FAN Donglin, TANG Tingyuan and LIN Xingchen
  • Abstract:Evaluating the value of ecosystem services is an important indicator to measure the development status of grassland ecosystems. Quantitative analysis of dynamic changes in ecosystem service values is of great significance to protect grassland resources. This paper used MODIS images and annual precipitation data from 2000 to 2015 to build a quantitative system for evaluating the value of ecological services of Xilingol League. The values of six service functions of grassland ecosystem, namely, product provision, nutrient cycling, carbon and oxygen balance maintenance, water conservation, soil maintenance, and entertainment, were calculated and dynamic changes in each banner, city and county of the research area were discussed. The results show that the total service value provided by the grassland ecosystem in Xilingol League from 2000 to 2015 exhibited a fluctuating increasing trend, with a 2.52% annual growth rate and increasing 3.371 billion yuan. However, the development of grassland resources among banneres, cities and counties was imbalanced (annual growth rate range from -0.46% to 1.71%), and even showed negative growth in service value in Zhengxiangbai Banner (annual growth rate was -0.30%) and Taipusi Banner (annual growth rate was -0.46%). The value derived from service functions provided by grassland ecosystem varied greatly. The function of maintaining carbon and oxygen balance accounted for 35% of the total value, while product provisioning accounted for only 5%, and the function of water conservation, which played a vital role in the protection of grassland ecosystem only accounted for about 1.5%. This research will provide a reference for the dynamic estimation of grassland ecosystem services in Inner Mongolia Autonomous Region and even Beijing-Tianjin-Hebei region.
  • DownLoad:Dynamic evaluation of grassland ecosystem services in Xilingol League.PDF
  • Application of landscape ecological redline based on ecosystem services in mainland China's coastal reclamation area
  • Authors:XIAO Tiantian, LI Yangfan and XIANG Zhiyuan
  • Abstract:Natural features and ecosystem conditions at coastal zones have been changing with sea reclamation activities, intensive human exploitation, and utilization. The study area is located in a coastal reclamation area in mainland of China. Vector data for the coastal reclamation area were obtained using a human-computer interactive visual interpretation method. Based on the vector data, the impacts of coastal reclamation on changes in the landscape types and ecosystem services in the coastal reclamation area were evaluated. Important eco-zone and eco-fragile areas were identified based on the results of ecosystem service assessment. The main conclusions of this study were as follows:(1) The characteristics of the Landscape Ecological Redline in the coastal reclamation area showed a generally dispersed and regionally centralized distribution. (2) The Landscape Ecological Redline was distributed in the landscape of artificial wetland and remaining natural wetland. The sea reclamation area is important for researching the integration of land and sea. These results provide data support and methods for integrating the land and sea as a research case to improve management systems of the land and sea.
  • DownLoad:Application of landscape ecological redline based on ecosystem services in mainland China's coastal reclamation area.PDF
  • Developing a social context analysis tool to facilitate communities' conservation behavior in protected areas: an experiment in the Wuyishan National Park Pilot
  • Authors:HE Siyuan, SU Yang, WANG Lei and CHENG Hongguang
  • Abstract:This study used the "common pool resources" theory, "environment entitlement" theory, and "socio-ecological framework" to analyze how the existing institutions affect ecosystem management by communities and eventually the status of the ecosystem. To prove targeted policies, we eventually developed a context diagnostic tool for community resource use in protected areas. This tool is being updated and experimented in the Wuyishan National Park Pilot through knowledge co-production realized by communities' perception and researchers' observation. The key factors affecting resource accessibility mainly include land policy at the macro scale, protected area planning and management at the meso scale, and village convenance at the micro scale, indicating the combined effect of legal force and folk norms. The key institutions affecting access to ecosystem services and well-being include mainly the formal institutions, such as market and credit systems at the meso scale, and informal institutions that are long-formed for maintaining development, mainly through some collective actions. The study also suggests that a negotiation procedure is necessary to motivate communities' acceptance of new rules and participation in the construction of national park, during which the institutional changes are meant to sustain the ecosystem services. The negotiation thus aims to set management rules in a way that the (1) procedure is legitimate and fulfills the autonomy of the communities, (2) content respects the history and tradition, and is formed based on abundant available information, and (3) implementation of the agreement depends on clear cost-benefit analysis. In this way, the perception of ecosystem from communities may tend to converge with the goal of conservation. Therefore, the diagnostic tool can help prescribe targeted policies to improve ecosystem management during the experimental period in national parks, to reach a win-win goal for the integrity of ecosystem and human well-being through institutional change.
  • DownLoad:Developing a social context analysis tool to facilitate communities' conservation behavior in protected areas: an experiment in the Wuyishan National Park Pilot.PDF
  • Spatiotemporal change of land ecological security in Xinjiang
  • Authors:LIU Shidong, XU Liping and ZHANG Jie
  • Abstract:Land ecological security assessment can guide rational land use efficiently and coordinate the contradiction between ecological protection and regional economic development. Supported by the kernel density estimation method and Kriging spatial interpolation, the index system of land ecological security evaluation based on catastrophe progression method has been constructed, and the spatial variation coefficient method and grey prediction model have been used to analyze the land ecological security in Xinjiang. The results indicated that:(1) the overall level of land ecological security in Xinjiang has continuously improved. The land ecological security index increased from 0.76 in 2004 to 0.94 in 2017; the development trend of "unsafe→less safe→critical safety→safer" is apparent at the ecological security level; (2) the disequilibrium of land ecological security has been improved and spatial differences have been reduced in all counties and cities of Xinjiang. The spatial variation coefficient of land ecological security in Xinjiang increased from 0.51 in 2004 to 0.84 in 2017. There has been a sustained upward trend, with the fastest increase of 0.29 between 2009 and 2014; (3) the population of the research area increased by 27.59%, whereas the area of unused land and grassland decreased by 7.51‰ and 9.45‰, respectively. The uneven distribution of natural resources, extensive occupation of unused land and grassland for socio-economic development, and sharp increase in regional population may be the main problems of land ecological security in Xinjiang; (4) through the gray model prediction, the land ecological security of Xinjiang will be further improved in 2020, and the spatial difference of land ecological security will be further reduced. Compared with the scenario in 2005, the spatial variation coefficient will increase to 0.85 in 2020; the safety and critical safety zones will be increased by 2.06% and 11.24%, respectively; and the safer, less safe and unsafe zones will be reduced by 2.98%, 9.16%, and 1.15%, respectively.
  • DownLoad:Spatiotemporal change of land ecological security in Xinjiang.PDF
  • Improving management of Giant Panda National Park by quantitative assessment of ecological management
  • Authors:ZHAO Zhiguo, LUAN Xiaofeng, CHEN Junzhi, YE Jing, LI Jingxin, ZHANG Chao, LI Miaomiao, WANG Hekunyuan and YANG Li
  • Abstract:Quantitative evaluation of ecosystem management is a primary premise to protect regional ecological security, rationally exploit resources, and achieve sustainable development. In this study, we collected information on potential ecosystem service, human influence, conservation for flagship species, and ecological management. We developed an assessment indicator system for quantitative evaluation of ecosystem management in the Giant Panda National Park (Sichuan Area);Sixteen indicators were included. According to the entropy theory, the dataset created by indicators were selected to evaluate disorder or development tendency of the system quantitatively. The results showed the following. (1) Entropy flow of ecosystem management in the Giant Panda National Park was-0.8309, indicating that the degree of order of ecosystem is increasing and the health status is optimum. Entropy flow on five prefectures were positive; the ecosystem tended to be disordered and on the verge of degradation. (2) Negative entropy flow was from the primary industry (agriculture), whereas, the positive entropy was from flagship species conservation and effective environmental management. Entropy flow varied among different prefectures. The system received the maximum value in Baoxing Xian (0.0880) and the minimum value in Jiuzhaigou Xian (-0.1826). Based on rural residents' income and entropy flow assessment, several actions should be carried out as soon as possible.Management experience from demonstration area should be the priority, and it should be applied at hotspot for management, including Pingwu Xian,Baoxing Xian, and Mao Xian.The tradeoff between regional development and conservation should be balanced for management.
  • DownLoad:Improving management of Giant Panda National Park by quantitative assessment of ecological management.PDF
  • Establishment and application of the index system for health assessment of the middle and lower reaches of the Hanjiang River
  • Authors:SU Yifan, LI Weiming, AI Zhiqiang, LIU Defu, ZHU Chenghao, LI Jinjing and SUN Xuyang
  • Abstract:River ecosystem is one of the most important natural ecosystems. It plays a vital role in the exchange of material, energy and information. Humans have been altering natural rivers for different purposes such as navigation, irrigation, flood control, and power generation. While great social and economic benefits are achieved, these projects can cause ecological problems such as eutrophication, black and odorous water, and insufficient eco-flow. The problems of river ecosystem health as a result of human activities have drawn great attention. Questions remained unclear regarding river management. One is the method to evaluate river health condition affected by humans. The other is to minimize the adverse impact of water conservancy and hydropower projects on river ecosystem. In this study, a river health evaluation method was proposed from the perspective of ecosystem integrity, stability, and sustainability. The proposed method is based on the harmony theory, the comprehensive weight model combined with the least squares method, and the entropy coefficient method. A new framework for assessing river health was developed from the perspective of harmony and health between hydraulic engineering and the river ecosystem. As a case study, the method and framework were applied to the middle and lower reaches of the Hanjiang River, an important tributary of Yangtze River, China. The health status of the river ecosystem and crucial drivers were evaluated. The results indicated that:(1) a total of 11 indicators including sediment transport, river connectivity, eutrophication status, fish biological integrity index, etc. contributed to the index system for health assessment of the studied site; (2) the ecological environment of Hanjiang water was generally poor and change gradually along the river. River health levels were generally "healthy" in the upstream, mostly "sub-healthy" in the midstream, and "unhealthy" in the downstream. This indicates that pollution in Hanjiang River was more serious in the downstream; (3) the physical attributes of the river were altering to that of a lake due to an increasing number of cascaded dams and inter-basin water transfer projects. The speed of such a change scales with the extent of hydraulic engineering intervention. This study will serve as an important reference for basin management in Hanjiang River.
  • DownLoad:Establishment and application of the index system for health assessment of the middle and lower reaches of the Hanjiang River.PDF
  • Analysis of the coupling relationship between ecological vulnerability and economic poverty in Qinling-Dabashan contiguous poor areas: a case study of Shanyang County in Shaanxi Province, China
  • Authors:WANG Zhao, LIU Jianhong, LI Tongsheng, RUAN Zheng and WU Fengqi
  • Abstract:Shanyang County is one of the key counties of national poverty alleviation in Qingling-Dabashan contiguous poor areas. Shanyang County was used as a study area, and the ecological vulnerability index based on remote sensing and geographic information methods was assessed. In addition, a village-level poor economic evaluation index system was constructed, and the level of economic poverty of 239 villages in the study area was evaluated. Based on this, the coupling coordination degree of ecological vulnerability and economic poverty were evaluated, and the spatial variability of the coupling coordination degree was analyzed in the study area. The results showed that the overall vulnerability of Shanyang County was above the intermediate level, and the areas with high ecological vulnerability were mainly distributed in the valley width and strath terrace with frequent human activities and serious soil erosion. The overall poverty level in Shanyang County was high, and the terrain conditions, abundance of resources, traffic accessibility, and economic locations all contributed combined effects in the spatial distribution pattern of economic poverty in Shanyang County. The coupling coordination degree of ecological vulnerability and economic poverty were divided into six types. They included economic environmental common damage, economic environmental damage, economic damage, synchronous development, environmental lag, and economic lag type. The percentage of the synchronous development type was only 13%, and the overall coupling coordination degree of ecological vulnerability and economic poverty was low. The economic environmental common damage type, synchronous development type, and environmental lag type had a scattered distribution. The economic damage type, economic environmental damage type, and economic lag type were significantly concentrated, and the economic damage type and the economic lag type had distributions centered in the valley width and strath terrace, whereas the economic environmental damage type was distributed in the remote mountainous area. Based on the construction of the evaluation index system of ecological vulnerability and poverty, and applying the coupling theory to analyze the coupling coordination degree of spatial distribution at the county-village level, the goals of this study were to explore the cause for the mechanism of ecological vulnerability and poverty, and to improve the ecological environment in the Qingling-Dabashan contiguous poor areas. It is of great significance to target the regional poverty alleviation policy and realize sustainable development.
  • DownLoad:Analysis of the coupling relationship between ecological vulnerability and economic poverty in Qinling-Dabashan contiguous poor areas: a case study of Shanyang County in Shaanxi Province, China.PDF
  • Integrated assessment of marine ecological vulnerability in the Yangtze River Estuary using GIS
  • Authors:HE Yanlong, YUAN Yiming, WANG Teng, ZHANG Haofei and CHEN Yaohui
  • Abstract:Climate change, eutrophication, and habitat fragmentation are ubiquitous ecological problems in the world. It is important to conduct scientific assessment of the external pressure and the resilience of ecosystems for the ecological management and restoration. In the case of the Yangtze River Estuary, as the end of the basin, huge amounts of pollutants were carried into the area, which resulted in the degeneration of the ecosystem during the past decades. However, little is known about the tendency of ecological vulnerability in this area under the effects of human activities and climate change. Consequently, the ecological vulnerability in the Yangtze River Estuary was assessed using geographic information system (GIS) software combined with spatial principal component analysis (SPCA). An analytical hierarchy process (AHP) was used to determine the evaluation factor weightings. According to the ecological vulnerability index (EVI) values, the eco-environmental vulnerabilities of the study area were classified into five levels:potential (< 0.5), light (0.5-0.8), moderate (0.8-1.0), heavy (1.0-1.2) and very heavy (1.2-1.5). The results showed that the inner mouth area of the Yangtze River Estuary was the most vulnerable. There was a significant decrease tendency in EVI from the inside to the outside of the mouth. The spatial distribution of the very heavy vulnerable areas within the mouth has shifted southward in the last five years. The extremely vulnerable area of about 2000 km2 has changed in the assessment area with extremely vulnerable area decreased by 7% and severely vulnerable area decreased by 5%. One the other hand, the ecological environment status out of the Yangtze River Estuary has obviously improved from 2013-2017. In general, the input of large amount of land-based pollutants and the instability of the ecosystem caused by human activity were the main factors for the high vulnerability of the Yangtze River Estuary.
  • DownLoad:Integrated assessment of marine ecological vulnerability in the Yangtze River Estuary using GIS.PDF
  • An Ecopath evaluation of system structure and function for the Laoshan Bay artificial reef zone ecosystem
  • Authors:LIU Hongyan, YANG Chaojie, ZHANG Peidong, LI Wentao and ZHANG Xiumei
  • Abstract:Based on an investigation in the Laoshan Bay artificial reef zone from 2014-2016, a trophic model of the Laoshan Bay artificial reef ecosystem was constructed using Ecopath with Ecosim software to analyze the energy flow pattern and attributes of the ecosystem, estimating the carrying capacity of Chlamys farreri. The model included 17 functional groups, covering nearly all the main processes of the energy flow in Laoshan Bay artificial reef ecosystem. Network analysis showed that the trophic level of the functional groups varied from 1.0-4.255, and Conger myriaster occupied the highest trophic level. Five discrete trophic levels were found, and the mean trophic transfer efficiency was 10.8%, with a mean transfer efficiency of 10.9% from detritus and 9.8% from the primary producers within the ecosystem. The total system throughput was estimated to be 14256.510 t km-2 y-1, with 68% originated from detritus. The ratio of total primary productivity to total respiration of the system, the connectivity index, and the omnivory index were 1.127, 0.293, and 0.333, respectively, showing an ecosystem with a high maturity, a complex food web, and a high internal stability. The key species index analysis showed that Sebastes schlegelii had a high keystone index and relative overall effect, indicating that it may play an important ecological role in the current ecosystem. The ecological capacity of the ecosystem for Chlamys farreri culture is 189.679 t/km2; the current stock may increase by 18.55% of the current level.
  • DownLoad:An Ecopath evaluation of system structure and function for the Laoshan Bay artificial reef zone ecosystem.PDF
  • Analysis of temporal-spatial patterns and influencing factors of urban ecosystem carrying capacity in urban agglomeration in the middle reaches of the Yangtze River
  • Authors:SHEN Wei, LU Fengxian, QIN Yaochen, XIE Zhixiang and LI Yang
  • Abstract:The urban agglomeration in the middle reaches of the Yangtze River is within a typical ecologically sensitive area as well as a key development area in China. Scientific assessment of its ecological carrying capacity has important scientific value and practical significance. On the basis of both the components and structural characteristics of urban ecosystems, in this study, we used state-space techniques to construct a comprehensive evaluation index system for the urban ecosystem carrying capacity from three dimensions:socio-economic coordination, resource and environmental supply, and ecological elasticity. Spatial analysis, multiple regression, and geographically weighted regression were used to analyze the temporal-spatial patterns and other factors influencing the urban ecosystem carrying capacity in an urban agglomeration in the middle reaches of the Yangtze River from 2006 to 2015. The results indicated that:(1) the urban ecosystem carrying capacity of study area presents a W-shaped fluctuating increasing trend. The dimension of socio-economic coordination follows a fluctuating decreasing tendency, while the dimensions of resource and environment supply and ecological elasticity are increasing with fluctuations. (2) With regard to the perspective of spatial patterns, the urban ecosystem carrying capacity of study area is characterized by an obvious space correlation and heterogeneity. Two hot spots formed in the Poyang Lake urban agglomeration and the area around the Dongting Lake, and two cold zones formed in the core area of the Wuhan urban agglomeration and the urban agglomeration around Changsha-Zhuzhou-Xiangtan. (3) The factors of social development level, income level of urban inhabitants, population density, economic development efficiency, resource supply level, and environmental pollution control level exert significant effects on the spatial differentiation pattern of the urban ecosystem carrying capacity in urban agglomeration in the middle reaches of the Yangtze River. Moreover, the intensity shows a spatial heterogeneity characteristic.
  • DownLoad:Analysis of temporal-spatial patterns and influencing factors of urban ecosystem carrying capacity in urban agglomeration in the middle reaches of the Yangtze River.PDF
  • Precipitation pulse patterns and their spatiotemporal variation in desert steppes: a case study in the Darhan Muminggan Joint Banner
  • Authors:SONG Yifan, LU Yajing, GUO Zhongxiao, XU Xiaomin, HAO Weigang, LIU Huiwen and HAN Zhenhua
  • Abstract:Against the backdrop of global climate change, precipitation patterns in desert steppes have undergone varying degrees of disturbance. There is a particular significance in recognizing these alterations for both the hydrology and ecology of the changing environments of desert steppes. In this study, daily data from three meteorological stations located in regions of different precipitation gradients in the Darhan Muminggan Joint Banner were used to analyze precipitation patterns in desert steppes and their variation characteristics. Unlike previous studies on this topic, this research utilized precipitation events from areas of different precipitation gradients for comparison at the same temporal scale. Precipitation events of different levels were analyzed to determine the precipitation composition of desert steppes and its spatiotemporal variation. The results indicated that, overall, as the annual precipitation decreased, the fluctuation in the number of precipitation days and the precipitation amount in the study area gradually increased. Also, the fluctuations in precipitation amount were significantly greater than the fluctuations in the number of precipitation days, which meant that precipitation amount had greater spatiotemporal variability than the number of precipitation days. The proportions of the number of precipitation days of 0-5 mm, 5-10 mm, and >10 mm precipitation events were 77%-80.9%, 11.5%-12.2%, and 7.6%-10.9%, respectively, while the precipitation amount proportions of 0-5 mm, 5-10 mm, and >10 mm precipitation events were 25.2%-32.2%, 21.9%-25.4%, and 42.4%-52.9%, respectively. The mean precipitation amounts on a rainy day with 0-5 mm, 5-10 mm, and >10 mm precipitation events were 1.2-1.3 mm/d, 7.0-7.1 mm/d, and 17.8-19.2 mm/d. From the annual distribution of precipitation events of different levels, which were affected by the combination of the southeast monsoon and the terrain, it could be seen that the 0-5 mm precipitation events were mainly concentrated from June to September in the growing season. The 5-10 mm precipitation events occurred mostly in July, and the >10 mm precipitation events predominantly occurred in August. Both the amount of precipitation and the number of precipitation days showed an increasing trend in the study area. A major feature of pulse precipitation from 1960 to 2013 in the desert steppe region of the study area was that 0-5 mm precipitation events showed an increasing trend in terms of both the precipitation amount and the number of precipitation days. In the Bailingmiao and Mandulla regions, where annual precipitation was relatively low, both the number of precipitation days and the precipitation amount showed an increasing trend for all precipitation levels. This was another significant feature of precipitation events in the study area. However, in the Xilamuren region, where the annual amount of precipitation is relatively high, there has been a shift in the internal precipitation structure from large and medium precipitation events to small precipitation events, although the annual precipitation continues to show an increasing trend. The annual precipitation and growing-season precipitation had 2.84-4.5 a main periods. The differences among the precipitation gradients are inconspicuous, and from the perspective of the precipitation events of different levels, the overall trend indicates that the higher the precipitation level, the shorter the cycle of precipitation events.
  • DownLoad:Precipitation pulse patterns and their spatiotemporal variation in desert steppes: a case study in the Darhan Muminggan Joint Banner.PDF
  • Spatial downscaling of forest biomass based on remote sensing
  • Authors:LIU Qinru and SUN Rui
  • Abstract:Forest biomass is an important indicator that can be used to evaluate global carbon-oxygen balance and climate change. At present, the spatial resolution of existing global forest biomass products based on spaceborne large footprint LiDAR data is too coarse to meet the needs of local forest investigation and dynamic monitoring. Therefore, it is necessary to determine a downscaling method to produce high spatial resolution forest biomass products from coarse resolution products. Two areas with different forest distribution patterns in Maryland, USA, were selected in this study to establish statistical relationships between low resolution multispectral data upscaled from TM data and forest aboveground biomass (AGB), which were upscaled from CMS (Carbon Monitoring System) forest AGB products or directly from GEOCARBON AGB products. The statistical relationships were then used as a downscaling model to downscale the forest AGB products from a spatial resolution of 1 km to 30 m. Results showed that the spatial distribution of downscaled 30 m-resolution biomass from simulated forest AGB was roughly the same as that of the CMS biomass. The RMSE was between 59.2 Mg/hm2 and 65.5 Mg/hm2. The correlation coefficient reached 0.7. Downscaled 30 m-resolution biomass from GEOCARBON forest AGB had a higher RMSE, which was between 75.3 Mg/hm2 and 79.9 Mg/hm2. Compared with the linear model, the non-linear model showed the relationship between AGB and multispectral data more effectively. In general, there was an AGB underestimation at high values and overestimation at low values.
  • DownLoad:Spatial downscaling of forest biomass based on remote sensing.PDF
  • Response in productivity of natural vegetation to drought in northeast China based on MODIS
  • Authors:YU Chenglong and LIU Dan
  • Abstract:Drought has a far-reaching influence on global terrestrial ecosystems. There is a typical difference between dry and wet areas, and a trend of a gradual increase in dry areas toward northeast China. This study was conducted to determine the response of natural vegetation productivity to drought in northeast China. Using the data published by MODIS, precipitation data, scPDSI, and statistical methods, characteristics of drought distribution and precipitation distribution in northeast China (including Heilongjiang Province, Jilin Province, Liaoning Province, and the eastern region of Inner Mongolia) were investigated and the spatio-temporal evolution law of NPP (Net Primary Productivity), LAI (Leaf Area Index), and CUE (Carbon Use Efficiency) of natural vegetation were analyzed. The response of natural vegetation to independent drought events and persistent drought were investigated based on the above research results. The results showed that:① From the average level in 2002-2013, the annual average of NPP and LAI of forests was significantly higher than that of grasslands, and the annual average of CUE was slightly lower than that of grasslands; ② Forests and grasslands responded to independent droughts by lowering NPP and LAI, which were significantly lower in the third year after the drought than before, LAI was significantly higher in the second year after the drought year than before, and the change lasted at least four years after the drought year. NPP and LAI of grassland had significant changes only in the year of independent drought; ③With the persistence of drought, the proportion of NPP in forests increased, and the increasing likelihood of ΔLAIDryn in the forests with lower LAIBaseline was greater with the duration of drought. Grasslands also had a certain ability to be suitable for persistent drought, and the increasing likelihood of ΔNPPDryn, ΔLAIDryn, and ΔCUEDryn in the grasslands with lower NPPBaseline, LAIBaseline, and CUEBaseline was respectively greater with the duration of drought; ④ The level of CUE change in the forest or grassland was rarely significant, and the law of change was less significant than NPP and LAI regardless of the independent drought event or the persistent drought. This study contributes to improving the evaluation of the influence of drought on natural ecosystems.
  • DownLoad:Response in productivity of natural vegetation to drought in northeast China based on MODIS.PDF
  • Differences in community characteristics, species diversity, and their coupling associations among three Quercus acutissima forests in Qiaoshan
  • Authors:ZHANG Weiwei, XUE Wenyan, YANG Bin and ZHAO Zhong
  • Abstract:To understand the coupling relationship between forest community characteristics and species diversity, three typical communities (pure forest of Quercus acutissima, mixed forest of Q. acutissima with various broad-leaved trees, and mixed forest of Q. acutissima with Pinus tabuliformis), were selected at Qiaoshan, southern Loess Plateau, to measure the community characteristics (height, diameter at breast height, and coverage). According to these indices, important values and species diversity were calculated, and redundancy analysis (RDA) was performed. The results showed that (1) the height and diameter at breast height and clear tree bole height of the arbor layer of Q. acutissima with P. tabuliformis were the highest in the mixed forest; the shrub height, shrub crown width, shrub ground diameter, shrub coverage were the highest in the mixed forest of Q. acutissima with various broad-leaved trees; and the herb ground diameter, herb coverage, and herb crown width were the highest in pure forest of Q. acutissima. (2) In three different forests, the important value of Q. acutissima in the tree layer was maximal, and the dominative species in the shrub layer were Sophora viciifolia, Celastrus orbiculatus, and Lespedeza bicolor, and that in the herb layer was Carex tristachya. (3) The biodiversity index of trees and shrubs in the mixed forest of Q. acutissima with P. tabuliformis were the highest, while the diversity index of herbs in the mixed forest of Q. acutissima and various broad-leaved trees were the highest. (4) There were differences in the relationships between the community structure characteristics and species diversity of different types of Q. acutissima forests. In the mixed forests of Q. acutissima with P. tabuliformis, the DBH, new twig length, and height of the shrub had the highest impact on species diversity. In the mixed forests of Q. acutissima with various broad-leaved trees, the height and crown width of the shrub had the highest impact on species diversity. In the pure forests of Q. acutissima, the DBH had the highest impact on species diversity. (5) Tree diameter breast height, tree height, and species diversity in the Q. acutissima with P. tabuliformis forest and in the mixed forest of Q. acutissima with various broad-leaved trees were higher than that in the pure forest of Q. acutissima. We can conclude that these two forest types have high wood productivity and ecological protection capacity, and can be the direction of future forest management.
  • DownLoad:Differences in community characteristics, species diversity, and their coupling associations among three Quercus acutissima forests in Qiaoshan.PDF
  • Estimation of carbon sequestration potential of forest biomass in China based on National Forest Resources Inventory
  • Authors:LIU Yingchun, GAO Xianlian, FU Chao, YU Guirui and LIU Zhaoying
  • Abstract:Forests are the largest carbon pools and sinks of terrestrial ecosystems worldwide. Forest carbon sequestration is an important method for reducing industrial greenhouse gases (GHG) emissions, and an option for conducting nationally determined contributions (NDCs) in most countries that signed the Paris Agreement, which aims to help humans limit global temperature increases by no more than 2℃ from pre-industry level. Most countries prepare national GHG inventories based on forest resources inventory data, which is considered as the most acceptable method. However, a few countries estimated the carbon sequestration potential of forests to offset the industry GHG emission in the future because of the uncertainty of forest carbon sequestration. Estimation of the carbon sequestration potential of forests based on forest resources inventory requires an improved understanding of forest growth and forestry sustainability. In this study, based on the publicly available National Forest Resources Inventory of China, we established a forest volume increase model for natural and planted forests of 36 forest types and five age groups at the national and provincial levels. We used the biomass expansion factor (BEF) to calculate the annual biomass from volume and estimated the carbon carrying capacity and carbon sequestration potential of China's forest biomass in a baseline scenario (maintaining the current state of afforestation, management, disturbance, climate, harvesting, etc.). The results showed that the annual volume increase in natural forests was lower than that in planted forests. For natural forests, the volume slowly increased initially, then rapidly, and then slowly again. Young and over-mature forests increased slowly, while the middle, pre-mature and mature forests increased rapidly. For planted forests, the volume initially increased rapidly and then then slowly. Young, middle, and pre-mature forests increased rapidly, while mature and over-mature forests increased slowly. The carbon carry capacity of Chinese forests was 12.82 Pg C in the baseline scenario, in which the natural and planted forests showed values of 6.2 Pg C and 6.6 Pg C, respectively. The planted forests will reach a peak in 2085, and the natural forests will continue to absorb carbon after 2140. In 2200, the carbon sequestration potential of China's forest biomass will be 6.52 Pg C compared to the forest carbon stock in 2001. Thus, China's forests can conservative sequestrate of 6.52 Pg C even without any improvement or enhancement in forest management. The carbon sequestration potential is 6.52-13.57 Pg C based on our study and published studies. This study can help to improve forest productivity model and planning of climate change mitigation policies and forest management.
  • DownLoad:Estimation of carbon sequestration potential of forest biomass in China based on National Forest Resources Inventory.PDF
  • Effects of pruning Caragana microphylla shrubs on the spatial distribution patterns of neighbouring plant communities
  • Authors:DING Xinfeng, HAO Guang, DONG Ke, WANG Yukun, GAO Shaobo, CHEN Lei, HE Xingdong, ZHAO Nianxi and GAO Yubao
  • Abstract:Over recent decades, the Inner Mongolia Steppe has degraded seriously owing to global climate change and extreme human activities, and the population of Caragana microphylla (a native leguminous shrub) spread quickly in the degraded regions. To relieve the pressure of shrub-encroachment and promote the restoration of degraded grasslands, several measures, such as pruning, have been carried out. However, little is known about how pruning affects the community patterns and soil physical and chemical properties. In the present study, we selected a C. microphylla-dominated grassland in Zhenglan Banner, Inner Mongolia Autonomous Region, and set up pruning and non-pruning (control) plots with a combination of sites at different distances to the shrub edge (0.5 and 2.5 m distances, named 0.5 and 2.5 m-site), as treatments to investigated the soil characteristics and spatial distribution patterns of neighbouring plant communities by Null-model. The results were as follows.(1) Soil total carbon, soil total nitrogen, and Pielou evenness index were significantly (P < 0.05) influenced by pruning treatments, but not by sites, being significantly higher under pruning treatments than those under non-pruning treatments; (2) Under non-pruning treatments, the community spatial distribution patterns were dominated by competition; however, under pruning treatments, community spatial distribution patterns showed less competition, and the 2.5 m-site under the pruning treatments was dominated by facilitation; (3) Only a few pairwise species were detected to have significant negative or positive interactions (the Standardized Effect Size was greater than 2 or less than -2), and they consisted of the dominant species of their communities. However, they still played a key role in explaining community spatial distribution patterns. The number of pairwise species that have significant negative interactions under pruning treatments was less than that under non-pruning treatments, suggesting less competition in pruning communities. The results not only provided an experimental basis for exploring variations in community spatial distribution patterns by pruning C. microphylla, but also provided practical guidance for the restoration of shrub-encroached grasslands.
  • DownLoad:Effects of pruning Caragana microphylla shrubs on the spatial distribution patterns of neighbouring plant communities.PDF
  • Ecological stoichiometry of Form. Quercus pannosa and Form. Pinus squamata in the Yaoshan Nature Reserve, Yunnan
  • Authors:YANG Xing, WANG Ping, GAO Dawei, GAO Ningning, LI Lushan, YANG Xiaoliu and ZHONG Qianjuan
  • Abstract:We aimed to elucidate the nutrient element content and soil nutrient supply capacity of two forest ecosystems-Form. Quercus pannosa and Form. Pinus squamata-in the Yaoshan Nature Reserve of Yunnan, by using four sample plots. The analysis of C, N, and P content; ecologic stoichiometry; and its correlation with "leaf-litter-soil" in the four sample plots revealed the following. (1) The content of C and N in the same component was significantly different, and the content of P was not significantly different. There were significant differences in the content of C and N among the components in the same sample plot, and it decreased in the following order leaf > litter > soil. The content of P decreased in the order leaf > soil > litter. (2) The C:P and N:P ratios of leaf, and the C:N ratio of litter and soil were not significantly different in the four sample plots, whereas, the other indicators were significantly different. The C:N, C:P, and N:P ratios of leaf, litter, and soil in the same land were significantly different, and decreased in the order litter > leaf > soil. (3) The leaf-soil C content and C:P ratio, and litter-leaf N:P ratio in the Form. Q. pannosa exhibited highly significant or significant correlation. There was highly significant or significant correlation between the litter-leaf C and N content, leaf-soil P content, and C:N and N:P ratios in the Form. P. squamata. (4) The lack of soil N is the main factor limiting plant growth. Phosphorus is mainly derived from soil mineral weathering, rather than the short-term biological cycle.
  • DownLoad:Ecological stoichiometry of Form. Quercus pannosa and Form. Pinus squamata in the Yaoshan Nature Reserve, Yunnan.PDF
  • Stoichiometric characteristics of leaves and litter in typical forest types on Sejila Mountain, southeastern Tibet
  • Authors:CAO Lihua, YIN Weiling, LIU Heman, YANG Hong, LIAN Yuzhen and GUO Fenglei
  • Abstract:The contents and dynamics of nutrients in leaves and litter are important for plant-soil nutrient cycling in forest ecosystems. Forests are one of the most important terrestrial ecosystems in southeastern Tibet, where the litter layer develops in an alpine climate. In this study we investigated the contents and stoichiometry of the most important nutrients (carbon, nitrogen, phosphorus, and potassium) in relation to the leaf age and stage of forest litter decomposition on Sejila Mountain (elevation approximately 3400-4150 m) in southeastern Tibet. We measured the organic carbon (OC), total nitrogen (TN), total phosphorus (TP), and total potassium (TK) contents in 1-a-old and 2-a-old leaves, and at different stages of litter decomposition (non-decomposed[ND], semi-decomposed[SD], and completely decomposed[CD]), in typical forest types (Rhododendron aganniphum, Abies forrestii, and Quercus aquifolioides). The OC contents of the leaf and litter showed the following rank order:2-a-old leaf > 1-a-old leaf > ND > SD > CD (65.71%, 71.29%, 60.58%, 41.15%, and 29.86%, respectively). The litter OC content decreased with an increasing litter decomposition. The leaf OC contents were higher than the average for China (45.5%). The leaf OC contents were significantly higher in the coniferous forest than in the broad-leaved forest, and those in both forest types were higher in older leaves than in new leaves (72.89% and 58.32% for 1-a-old leaves, and 78.31% and 64.29% for 2-a-old leaves, in the coniferous and broad-leaved forests, respectively). The contents of N, P, and K in the leaf were higher in the 1-a-old leaves than in the 2-a-old leaves. The TN content of the 1-a-old leaves was higher in the broad-leaved forest (11.23 g/kg) than in the coniferous forest (10.55 g/kg), whereas the TN content of the 2-a-old leaves in the coniferous forest (9.39 g/kg) was higher than that in the broad-leaved forest (7.15 g/kg). The TN and TP contents of litter were highest in the SD forest, which indicated that net fixation occurred during initial decomposition, whereas complete decomposition resulted in a net release of nitrogen and phosphorus. The litter TK content was elevated with increased decomposition, and thus showed net fixation during the decomposition process. The litter TN contents were lower than the average for Chinese forests (12.03 g/kg), and the average values were 6.59, 8.24, and 9.55 g/kg for ND, SD, and CD forests, respectively. The litter TP contents were higher than the average for Chinese forests (0.74 g/kg), and the average values were 1.17, 2.49, and 1.87 g/kg for ND, SD, and CD forests, respectively. The litter TK contents were 2.19, 3.33, and 4.67 g/kg for ND, SD, and CD forests, respectively. The leaf C:N, C:P, and C:K ratios were higher in the 2-a-old leaves than in the 1-a-old leaves; the ratios at each leaf age were 87.81 and 60.79 for C:N, 539.25 and 375.49 for C:P, and 139.15 and 101.20 for C:K, respectively. The litter C:N, C:P, and C:K ratios were decreased with increased decomposition. The ND, SD, and CD ratios were 90.20, 43.36, and 35.68 for C:N; 520.34, 167.60, and 159.13 for C:P; and 297.73, 129.97, and 64.42 for C:K, respectively. The leaf N:P ratios were low (6.09 and 4.76), and significantly lower than the global average (16.0), which was indicative of nitrogen limitation. The litter N:P ratios for ND, CD, and SD were 5.86, 4.51, and 3.90, respectively. The results provide valuable information on plant-soil nutrient cycling in forest ecosystems in southeastern Tibet.
  • DownLoad:Stoichiometric characteristics of leaves and litter in typical forest types on Sejila Mountain, southeastern Tibet.PDF
  • Litter decomposition rate of the Caragana korshinskii shrub: influencing factors in the desertified grassland ecosystems of Ningxia
  • Authors:LIU Jianan, CHANG Haitao, ZHAO Juan, ZHANG Anning, CHEN Wei, ZHANG Jing, LUO Yaxi and LIU Rentao
  • Abstract:In Yanchi County, Ningxia, the decomposition rates of C. korshinskii litter and the associated soil environment were sampled in microhabitats beneath very small, small, medium, and large shrub canopy sizes. Our study found that (1) during the decomposition process, soil moisture content and soil temperature indicated similar distributions in the four types of shrub canopy size, however, soil pH and soil electrical conductivity changed significantly among the four types. (2) no significant differences within the three mesh sizes between the four types of shrub canopy size in the decomposition rate of shrub litter in the litter bag was found. (3) no significant differences in the litter decomposition rate of shrubs in the litter bag within the three mesh sizes in the medium shrub microhabitat was found. In the very small shrub microhabitat, the decomposition rate of shrub litter within the three mesh sizes were 4 mm (40.95%) > 0.01 mm (38.51%) > 2 mm (32.14%) at 120 d. However, it followed the order of the three mesh sizes of 2 mm (37.64%) > 4 mm (35.20%) > 0.01 mm (26.68%) at 150 d. In the small shrub microhabitat, the decomposition rate of shrub litter within the three mesh sizes followed the order of 0.01 mm (46.81%) > 4 mm (41.07%) > 2 mm (34.75%) at 120 d, whereas it was found to follow the order of the three mesh sizes, being 2 mm (37.64%) > 4 mm (35.20%) > 0.01 mm (26.68%) at 150 d. In the large shrub microhabitat, the decomposition rate of shrub litter within three mesh sizes was 4 mm (39.65%) > 2 mm (36.65%) > 0.01 mm (35.96%) at 120 d. However, it was found to follow the order of the three mesh sizes, being 2 mm (48.05%) > 4 mm (35.96%) > 0.01 mm (30.80%) at 150 d. (4) according to the Olson index, it took 0.95 and 4.1 years for C. korshinskii litter within the three-size meshes to decompose at 50% and 95% respectively in the microhabitats of very small and medium shrub sizes. The litter in the small shrub microhabitats spent 0.63 a and 2.74 a (4 mm), 1.90 a and 8.21 a (2 mm), and 0.95 a and 4.1 a (0.01 mm), of the large shrub size spent 0.95 a and 4.1 a (4 mm), 0.63 a and 2.74 a (2 mm), and 1.90 a and 8.21 a (0.01 mm) with decomposition rates of 50% and 95%. It was concluded that differences in shrub canopy size microhabitats indicated little influence on litter decomposition rates. The results of this study suggest that the interaction between shrub size and soil faunal groups influences the litter decomposition process in the desert grassland ecosystems of Ningxia.
  • DownLoad:Litter decomposition rate of the Caragana korshinskii shrub: influencing factors in the desertified grassland ecosystems of Ningxia.PDF
  • Responses to non-structural carbohydrates and nitrogen and phosphorus content in the leaves of Magnolia sinensis along different altitude gradients
  • Authors:KANG Xikun, CHEN Xiaohong, GONG Wei and ZHANG Tengju
  • Abstract:Non-structural carbohydrates (NSC), nitrogen (N), and phosphorus (P) are important energy sources for plant growth, and their deficiencies affect plant growth factors. Magnolia sinensis is a rare and endangered species of wild plant in Sichuan province, and studies of its NSC, N, and P can reflect its nutritional supply level and adaptation strategies to the environment. The present study was conducted to evaluate M. sinensis at six altitudes (1840, 1960, 2070, 2170, 2270, 2390 m) in Lushan, and the NSC, N, and P content and their stoichiometry in the leaves at different altitudes were analyzed. The results showed that the soluble sugar content of M. sinensis in 2390 m leaves was significantly higher than that in 1840 m leaves. The NSC content at different altitudes was extremely significant, showing a unimodal change of "low-high-low" with increasing altitude. The NSC content of 2170 m leaves was the highest, and the carbohydrate supply was sufficient, ratio of soluble sugar/starch increased with altitude, N content and N/P ratio decreased with altitude, and N/P ratio was less than 14. The NSC/N ratio at 2390 m was significantly higher than that at 1840 m. The results showed that the soluble sugar and NSC content in the leaves of M. sinensis were not affected by the altitude, a higher soluble sugar content was beneficial for resisting the low-temperature environment, and growth was mainly limited by nitrogen but not by carbon. The protective strategies of NSC, N, and P in the limited distribution range of the endangered plant M. sinensis were determined, providing information on carbon metabolism and adaptation strategies used by this plant.
  • DownLoad:Responses to non-structural carbohydrates and nitrogen and phosphorus content in the leaves of Magnolia sinensis along different altitude gradients.PDF
  • Large scale shrub coverage mapping of sandy land at 30m resolution based on Google Earth Engine and machine learning
  • Authors:CHEN Qian, LI Xiaosong, XIU Xiaomin and YANG Guangbin
  • Abstract:Compared with the humid region in southern China, the sandy land vegetation is characterized by low coverage and a scattered spatial distribution in the north. Shrub is a dominant vegetation type in this region and plays an important role in sand control, food/timber product provision, etc. In view of the current lack of the medium- and high-resolution remote sensing products for shrub coverage at large-scale in arid regions, we proposed a new approach to estimate shrub coverage at large scale based on Collect Earth sample collector and Google Earth Engine (GEE) platform. Then this approach was applied to Mu Us sandy land, one of the four major sandy lands in Northern China. The results showed that:(1) Collect Earth sample collector could effectively obtain the ground shrub coverage sample data set for distinguishing shrubs from tall trees and herbaceous vegetation, which laid a foundation for the establishment of shrub coverage estimation; (2) Using Landsat data, other ancillary data, and the machine learning algorithm in GEE, the shrub coverage could be estimated effectively. The CART model had a deterministic coefficient R2 of 0.73 and a Root Mean Square Error (RMSE) of 13.66% with the estimated Accuracy (EA) of 61.8%. For SVM model, R2, RMSE, and EA were 0.72, 13.73%, and 61.6%, respectively. (3) The GEE-based approach proposed in this study could provide support to shrub coverage estimation in sandy land at the national and even the global scale with a potential application.
  • DownLoad:Large scale shrub coverage mapping of sandy land at 30m resolution based on Google Earth Engine and machine learning.PDF
  • Changes in floodplain vegetation in Poyang Lake wetlands
  • Authors:XIE Dongming, HUANG Qinghua, YI Qing, ZHU Zaiyu, ZHOU Guohong, TIAN Lei, ZHOU Yangming, JIA Junsong, QIAN Haiyan and XU Yuefeng
  • Abstract:The biodiversity and biomass of floodplain vegetation are important indexes to explain the ecosystem of wetlands and key methods to probe the response mechanism to water level change. Poyang Lake is the largest fresh-water lake in China and one of the most important wetlands globally. In a field survey, 3s technology and DEM data were used to analyze the variation in plant species diversity and biomass along the elevational gradient in Poyang Lake wetlands with α and β biodiversity indexes. The results showed that there was a complex gradient of both biodiversity and biomass characteristics for the floodplain vegetation (P < 0.001). The index of biodiversity is highest at 14-15 m in Banghu Lake and Sizhoutou floodplain; the index of biodiversity is the highest at 15-16 m in Zhanbeihu Lake and Beishenhu Lake floodplain, but the index of biodiversity is not obvious in Changhuchi Lake floodplain. The correlation between biodiversity/biomass and elevation was nonlinear, and with increasing elevation, the biomass initially increased to a peak value and then decreased. The maximum volume of biomass measured in the fronted floodplain and the shallow lakes were different (P < 0.05); the maximum volume of biomass was located at an elevation of 14-15 m in fronted marshland, and at an elevation of 15-16 m in the shallow lakes.
  • DownLoad:Changes in floodplain vegetation in Poyang Lake wetlands.PDF
  • Characterization of aggregate microstructure of black soil with different number of freeze-thaw cycles by synchrotron-based micro-computed tomography
  • Authors:JIANG Yu, FAN Haoming, HOU Yunqing, LIU Bo, GUO Xinyu and MA Renming
  • Abstract:In Northeast China, seasonal freezing and thawing have been shown to cause significant physical changes in soil. The change in soil microstructure might be attributed to the freeze-thaw action during early spring. The freeze-thaw action affects soil microstructure directly by affecting soil aggregate, which is the basic unit of soil structure. Synchrotron-based X-ray micro-computed tomography can nondestructively capture images of the interior structure with high resolution and strong contrast, and therefore, is an excellent tool to investigate the 3-D microstructure of soil aggregates. Samples of soil aggregates were collected from laboratory freeze-thaw tests with different number of freeze-thaw cycles, and the aggregates were scanned with micro-CT at a resolution of 3.25 μm. The microstructure of aggregates was visualized and quantified by the digital image analysis method using Image J software. The results showed that with the increase in number of freeze-thaw cycles, the soil porosity increased, and the proportion of extended pore and pores > 100 μm also increased. When the number of freeze-thaw cycles was >7, the aggregate porosities increased with the increase in number of freeze-thaw cycles. The results showed that the number of freeze-thaw cycles significantly influenced the structural characteristics of black soil aggregates. This study provides a theoretical basis for the study of freeze-thaw erosion and control of soil erosion during thawing in spring.
  • DownLoad:Characterization of aggregate microstructure of black soil with different number of freeze-thaw cycles by synchrotron-based micro-computed tomography.PDF
  • Research on the characteristics of soil nematode communities in alpine meadow in northern Tibet by using high-throughput sequencing
  • Authors:XUE Bei, HOU Lei and XUE Huiying
  • Abstract:The goal of this study was to examine the diversity of soil nematodes in the alpine meadows of northern Tibet. In August 2017, the changes in soil nematode communities at different soil depths were analyzed using high-throughput sequencing to reveal the community composition and structural characteristics. A total of 990 operational taxonomic units were extracted from five samples and were sorted into 3 classes, 7 orders, 25 families, and 30 genera. Enoplea was dominant in the different samples at the class level. The Chao1 index, Shannon index, and Ace index were used to evaluate the alpha diversity of the samples, and the results showed that the 5-10 cm soil layer had a relatively high abundance. A heatmap analysis showed the composition similarity of the community was 20-25 cm < 15-20 cm < 0-5 cm < 5-10 cm < 10-15 cm. A redundancy analysis of the soil nematode phyla and the chemical parameters in the soil showed that K+, soil water content, organic matter, and Zn2+ were the most related to the soil nematode community structure. Differences were noted in the species and abundance of soil nematodes at the different depths, which provides a basis for studying the characteristics of soil nematode communities in the alpine grasslands in northern Tibet.
  • DownLoad:Research on the characteristics of soil nematode communities in alpine meadow in northern Tibet by using high-throughput sequencing.PDF
  • Forest soil organic carbon and nitrogen storage and characteristics of vertical distribution in Qinghai Province
  • Authors:WANG Yanli, ZI Hongbiao, CHENG Ruixi, TANG Litao, SUOER Azhi, LUO Xueping, LI Jie and WANG Changting
  • Abstract:Forest soil plays a key role in regulating carbon and nitrogen cycle and mitigating the effects of global climate change. However, due to the differences in forest type, age, and altitude, there is still a great uncertainty about the estimation of forest soil carbon and nitrogen reserves. In this study, we used the measured data from Qinghai forest soil to estimate the density of organic carbon, nitrogen, and the storage of organic carbon and nitrogen pool, and their vertical distribution patterns. The results indicated that 1) the soil organic carbon density showed a unimodal change with the altitude with a maximum (34.33 kg/m2) at the altitude of 3100-3400 m; the nitrogen density increased with the increase in altitude, and ranged from 1.39 to 2.93 kg/m2. 2) In the 0-30 cm soil layer, the soil organic carbon and nitrogen density decreased with an increase in the soil depth, and their ranges were from 3.84 to 4.63 kg/m2 and 0.22 to 0.27 kg/m2, respectively. 3) Total soil carbon storage was 1098.70 Tg, and the total nitrogen storage was 61.78 Tg in the forest soil of Qinghai province at 0-100 cm soil layer. 4) There was a positive correlation between the altitude and nitrogen content, as well as between the altitude and nitrogen density (P < 0.01). There was a negative correlation between the soil depth and organic carbon content, and a positive correlation between the soil depth and organic carbon density and nitrogen density (P < 0.01). These results indicate that the altitude and soil depth are key factors influencing the distribution of organic carbon and nitrogen in forest soils in Qinghai Province.
  • DownLoad:Forest soil organic carbon and nitrogen storage and characteristics of vertical distribution in Qinghai Province.PDF
  • Effects of thinning and understory removal on soil nitrogen mineralization rate and temperature-sensitivity in a moso-bamboo plantation
  • Authors:LI Guangmin, CHEN Fusheng, XU Zhiwen, LIU Juan, ZHANG Yang, FANG Xiangmin and WAN Songze
  • Abstract:Nitrogen (N) is an essential element for plant growth, and only inorganic N can be directly absorbed by plants. Thus N mineralization and its temperature sensitivity are of significance to the biogeochemical cycle and ecosystem function. In the present study, field experiments in combination with thermostatic cultivation were conducted to investigate the effects of thinning intensities[25%thinning (25%Th) and 50%thinning (50%Th)] and understory removal (UR) on soil N mineralization and its temperature sensitivity in Moso plantation. The results showed that 25%Th significantly increased the soil N ammonification rate (P < 0.01), but it decreased the nitrification rate (P < 0.01). By contrast, 50%Th and UR had significant effects on the nitrification rate, but not on the ammonification rate. Specifically, 50%Th remarkably increased the nitrification rate (P < 0.01), whereas UR decreased the nitrification rate (P < 0.01). Correlation analysis showed that there were negative correlations between the ammonification rate and soil organic carbon content (SOC), total nitrogen content and total phosphorus content; the soil nitrification rate showed positive correlations with SOC and soil water content, but negative correlation with ammonium nitrogen (NH4+-N) content. Q10 was used to indicate the correlation between temperature and N mineralization. 25%Th decreased the Q10 of net N mineralization and ammonification, while UR increased that of nitrification. In general, Q10 under different treatments were 1.17 and 1.36. In conclusion, 25%Th and understory conservation are beneficial to soil N supply in Moso plantation.
  • DownLoad:Effects of thinning and understory removal on soil nitrogen mineralization rate and temperature-sensitivity in a moso-bamboo plantation.PDF
  • Plant diversity and its relationship with soil factors in the middle reaches of the Heihe River based on the soil salinity gradient
  • Authors:ZHAO Min, ZHAO Ruifeng, ZHANG Lihua, ZHAO Haili and ZHOU Yuangang
  • Abstract:Wetlands are a unique ecosystem formed by the interaction of water and land, and have the function of maintaining different plant community types, and greatly promote species richness of the region. Thus, wetlands have become a hot research area for biodiversity conservation. Wetlands are important for water and carbon cycle regulation, wildlife survival, biological diversity, and economic value; however, human activities along with severe environment changes have led to critical loss and degradation of wetland ecosystems. In particular, soil salinity accumulation exerts a significant impact on wetland plant diversity. In previous studies, soil salinity has been considered an important factor affecting plant diversity in arid and semiarid areas. This study aimed to characterize the relationship between plant diversity and other soil factors along the soil salinity gradient in the middle reaches of the Heihe River. There were 27 sites along the middle reaches of the Heihe River and a total of 87 sampling plots were investigated from July to August 2017. These included 9 sampling plots for trees and shrubs (30 m×30 m) and 78 sampling plots for herbs (1 m×1 m). Soil characteristics were analyzed, including soil salinity (SA), soil pH (pH), water content (WC), bulk density (BD), soil organic matter (SOM), total nitrogen (TN), total phosphorus (TP), available nitrogen (AN), available phosphorus (AP), and available potassium (AK). The sampling plots were divided into three salinity gradients by cluster analysis and included low salinity (S1), middle salinity (S2), and high salinity (S3) gradients. The results showed that a total of 102 plant species occurred in the plots, belonging to 30 families and 71 genera, indicating that the plant composition was relatively rich. Along the increasing soil salinity gradient, the community composition changed significantly, and the number of families, genera, and species decreased. The Margalef richness index (R) decreased from 1.03 to 0.55 and the Shannon-Weiner diversity index (H) decreased from 1.45 to 1.08, indicating that plant diversity decreased with the increasing gradient in the study area. The effects of other soil factors on plant diversity under different salinity gradients were studied using a redundancy analysis (RDA). The results showed that there were differences in soil factors affecting plant diversity under different salinity gradients. In low salinity pH, AK, and TN, in middle salinity pH, AP, and AK, and in high salinity SOM, TP, AK, and AN affected plant diversity. These findings are of great significance to the maintenance and management of plant diversity in the middle reaches of the Heihe River.
  • DownLoad:Plant diversity and its relationship with soil factors in the middle reaches of the Heihe River based on the soil salinity gradient.PDF
  • Species diversity of soil arbuscular mycorrhizal fungi in karst vegetation succession process
  • Authors:LIN Yan, HE Yuejun, HE Minhong, WU Chunyu, FANG Zhengyuan, HAN Xu, XU Xinyang and WANG Shixiong
  • Abstract:The karst ecosystem maintains rich microbial diversity, and the composition and structure of arbuscular mycorrhizal fungi changes with karst vegetation succession. In this experiment, we used a space-time substitution method to collect soil from tree, bush, and herb communities from Huaxi Guiyang, Zhijin Bijie, and Huajiang Guanling from a typical karst area located in Guizhou. Using Illumina HiSeq molecular sequencing technology, we performed an operation taxonomic unit (OTU) clustering analysis and compared the annotated species with those in a database to explore the soil arbuscular mycorrhizal fungi (AMF) species diversity during the different karst succession stages. There were 275 Glomeromycota OTUs in 19 species from 4 orders, 8 families, and 13 genera in the karst habitat soil. AMF abundance at the genus level showed that Rhizophagus was the dominant genus, and Huajiang had the highest AMF richness. The common species Septoglomus constrictum, Rhizophagus intraradices, Claroideoglomus sp.MIB8381,and Entrophospora infrequens were distributed at different stages of the vegetation succession at every sampling site. The Shannon and Simpson's indices of AMF changed at the different stages of succession as follows:in Huaxi, tree/bush > herb (P < 0.05); in Huajiang, bush/herb > tree (P < 0.05); and in Zhijin, tree > bush > herb, but these relationships were not significantly different. The Chao1 and abundance-based coverage estimation (ACE) indices showed that in Huajiang, bush/herb > tree (P < 0.05). The Spearman correlation analysis showed that soil total phosphorus was significantly and negatively correlated with the ACE index of AMF, and it was negatively correlated with the Chao1 index. Available phosphorus was negatively correlated with the Shannon and Simpson's indices. The canonical correlation analysis showed that soil total nitrogen, available nitrogen, organic matter, total phosphorus, and available potassium were significantly correlated with the community distribution of AMF. The results showed that although there was no uniform variation law, the diversity of soil AMF increased or decreased with the process of karst vegetation succession, which was closely related to the physicochemical properties of the soil, and the influence of phosphorus was the greatest.
  • DownLoad:Species diversity of soil arbuscular mycorrhizal fungi in karst vegetation succession process.PDF
  • Effects of biochar on soil nutrient, enzyme activity, and bacterial properties of Chinese fir plantation
  • Authors:HU Huaying, YIN Danyang, CAO Sheng, ZHANG Hong, ZHOU Chuifan and HE Zongming
  • Abstract:This paper aims to explore the interaction mechanism of the soil properties and nutrient contents, enzyme activity of the soil, and the abundance and activity of soil bacterial community structure and diversity, and impact analysis of three in Chinese fir plantation's red soil in southern China after biochars application. We cultivated and determined bacterial community in soil environment of the artificial Chinese fir forest by adding different biochars based on high-throughput sequencing technology. Four enzymes related to soil C and N cycling were selected to analyze the relationship between the four enzymes and the soil nutrient content and relative abundance of the soil bacteria. The results showed that the biochar application improved the soil pH, total phosphorus, available phosphorus, available potassium, and promoted the activities of soil-α-glucosidase, soil-β-glucosidase and urease, but had no significant effect on catalase. The increase of the Chinese fir leaf biochar was greater than fir wood chip biochar, while the total carbon content of soil with fir wood chip biochar was higher than that of the Chinese fir leaf biochar because the raw materials for biochar preparation and its own properties and substance content were different. The activity of C cycle soil-glucosidase increased more with low addition of biochar than with high addition of biochar, while the soil urease activity related to the N cycle increased with the increase of the biochar addition, especially 3% BL600 treatment had a significant effect on soil urease. Adding cedar leaf charcoal to soil could increase the soil bacterial abundance, while wood charcoal reduced the soil bacterial abundance, and low temperature charcoal was higher than high temperature charcoal. Adding biochar had direct influence on the soil pH value, total carbon, total phosphorus, available phosphorus and available potassium content. The soil composition and properties had different effects on the living habits and functions of different bacterial populations. The soil enzyme activities were closely related to soil bacteria. The changes in bacterial abundance caused changes in the soil enzyme activities. Therefore, the soil enzyme activities and bacterial communities relative abundance had a certain correlation with the response to the addition of biochar.
  • DownLoad:Effects of biochar on soil nutrient, enzyme activity, and bacterial properties of Chinese fir plantation.PDF
  • The ecological plasticity and its responses to soil factors of ramets of Phragmites australis in Zhalong wetland
  • Authors:JIAO Dezhi, YU Xinyu, WANG Yushen, PAN Lin and YANG Yunfei
  • Abstract:Phragmites australis in the Zhalong wetlands can not only form large areas of mono-dominant communities, but also form different community patches. By using large sample sizes and statistical analysis, a comparative study was performed on the height and biomass of ramets of P. australis populations in aquatic, wet, xeric, and saline-alkali habitats in wetlands. The results showed that in these four habitats, from June to October, the height and biomass of ramets of P. australis population were the highest in the aquatic habitat, and the lowest in the saline-alkali habitat; the height of ramets in the aquatic habitat was 1.5-2.3 times higher than that in the saline-alkali habitat; and the biomass of ramets in the aquatic habitat was 2.0-5.1 times larger than that in the saline-alkali habitat, while the difference and different orders among habitats were relatively stable. In the four habitats, the coefficients of variance in ramet height (19.45%-31.56%) among habitats were higher than those within habitats (8.07%-17.61%). The ramet height had a greater plasticity among habitats, while the coefficients of variance in ramet biomass (33.43%-5.61%) among the aquatic, wet, and saline-alkali habitats were lower than those within the habitats (44.85%-79.82%). Additionally, the ramet biomass had a greater plasticity within habitats. The ramets of P. australis populations in different habitats had great morphological plasticity in growth and production, showing obvious environmental effects, in which the soil moisture was the main positive driving factor (R > 0.80) of plasticity variation.
  • DownLoad:The ecological plasticity and its responses to soil factors of ramets of Phragmites australis in Zhalong wetland.PDF
  • Effects of long-term application of phosphorus fertilizer on fungal community diversity, composition, and intraspecific interactions and variation with application rate in a lime concretion black soil
  • Authors:MA Lei, ZHAO Wenhui, GUO Zhibin, WANG Daozhong and ZHAO Bingzi
  • Abstract:Phosphorus (P) deficiency is a limiting factor for agricultural production in the region covered with lime concretion black soil. Application of chemical P fertilizer is a common strategy to improve P availability. Numerous studies have demonstrated the essential role of P fertilization on soil fertility and crop yield, whereas relatively little is known about the effects of long-term P application on the belowground fungal community. The overall objective of this study was to investigate the effects of long-term P fertilization on fungal community diversity, composition, and intraspecific interactions in a lime concretion black soil, and to assess how the effects varied with application rate. Soils from a 21-year field experiment located in Mengcheng County, Anhui Province, were used, with treatments including three levels of P application rates, i.e. (1) P0:unamended control, (2) P1:chemical P fertilizer was applied at P2O5 45 kg/hm2, and (3) P2:chemical P fertilizer was applied at P2O5 90 kg/hm2. ITS1 gene pyrosequencing was employed to characterize the fungal community diversity and composition. The results showed that long-term P fertilization significantly improved soil fertility. Compared with the P0 treatment, the total P (TP) from the P2 and P1 treatments was 40.00% and 24.00% higher, and the available P (AP) was 384% and 144% higher, respectively. The Shannon index decreased with the P application rates, and was significantly negatively correlated with TP (r=-0.678, P=0.045) and AP (r=-0.677, P=0.045). Ascomycota was the dominant phylum in the studied soil, with its relative abundance being 65.71%-79.86%. Principal coordinate analysis (PCoA) revealed that the fungal community structure differed significantly among the different treatments. Redundancy analysis (RDA) further suggested that the fungal community structure was mainly determined by TP and dissolved organic carbon (DOC). Compared with the P0 treatment, the relative abundance of Ascomycota from P2 and P1 was 9.87% and 11.75% higher, and that of Sordariomycetes was 28.63% and 15.97% higher, respectively. Conversely, the relative abundance of Mortierellomycota from P2 and P1 was 42.63% and 43.81% lower, and that of Mortierellomycetes was 43.82% and 42.63% lower, respectively. Long-term P fertilization resulted in a significant enrichment of saprophytic fungi, namely, the genera of Plenodomus, Penicillium, and Arthrobotrys were enriched in the P1 treatment, and the genera of Cyphellophora, Zopfiella, Guehomyces, Mortierella, and Mucor were enriched in the P2 treatment. However, pathogenic (i.e., Simplicillium and Magnaporthiopsis) and symbiotic (i.e., Sagenomella and Nigrospora) fungi were depleted in the P1 and P2 treatments, relative to that of the P0 treatment. Co-occurrence network analysis revealed that long-term P fertilization increased network complexity, as reflected by the larger edge number and higher average degree in the P1 and P2 treatments than in the P0 treatment, which may enhance the network stability by reducing the spread of indirect effects in the treatments with P application. Moreover, the P1 and P2 treatments had a higher ratio of positive edges, indicating more cooperators in the P1 and P2 treatments, whereas more defectors occurred in the P0 treatment. Our results demonstrated that long-term P application can improve P availability, reduce fungal community diversity, alter fungal community structure, increase saprophytic taxa, eliminate pathogenic and symbiotic taxa, and enhance network complexity and stability in lime concretion black soil.
  • DownLoad:Effects of long-term application of phosphorus fertilizer on fungal community diversity, composition, and intraspecific interactions and variation with application rate in a lime concretion black soil.PDF
  • Characteristics of the spatial ecological niche of Bacillus-like genera in a microbial fermentation bed used for pig raising
  • Authors:LIU Bo, CHEN Qianqian, RUAN Chuanqing, WANG Jieping, ZHANG Haifeng, LIU Guohong, CHEN Zheng, PAN Zhizhen and LIU Xin
  • Abstract:The aim of this study was to investigate the characteristics of the spatial ecological niche of the Bacillus-like genera in a microbial fermentation bed (MFB) used for pig raising. To understand the ecological relationship between the environment and Bacillus-like genera, and thereby clarify the functions of pig feces degradation, odor elimination, pig disease prevention, and resource utilization, the random sampling method was used to obtain a total of 14 samples from the upper (0-20 cm) and under (40-60 cm) layers of the MFB. Nutrition condition analysis and metagenome sequencing methods were used to analyze the nutrition characteristics of the litter samples (organic matter, total nitrogen, humic acid, crude fiber) and growth conditions (moisture, pH), with identification of the Bacillus-like genera and determination of their relative abundance (reads). Cluster analysis, correlation analysis, spatial distribution analysis, and ecological niche width and overlap were used to reveal the characteristics of the spatial ecological niche and the relationships between it and other factors. A total of 24 Bacillus-like genera within six families were identified in the samples from the MFB (including two non-Bacillus genera), of which the genera Ammoniibacillus, Desulfuribacillus, and Tuberibacillus were all newly recorded genera in China. The three genera with the highest relative contents (reads) in the measured ecological niche were Bacillus (reads=8020), Lactobacillus (reads=4565), and Tuberibacillus (reads=1418), respectively. The total numbers of the Bacillus-like genera showed no significant differences (P > 0.05) between the upper and under layers of the ecological niche in the MFB. However, differences in the Bacillus-like genera were found at the level of their subcommunity structure:the top five genera with the highest contents were Bacillus (532.86), Lactobacillus (480.43), Geobacillus (88.86), Gracilibacillus (70.00), and Paenibacillus (40.86) in the upper layer, and Bacillus (612.86), Tuberibacillus (188.57), Lactobacillus (171.71), Paucisalibacillus (60.00), and Ureibacillus (46.71) in the under layer. The results showed that the five highest ecological niche breadth values of Bacillus-like genera were those of Bacillus (10.5159), Ornithinibacillus (8.6094), Paenibacillus (7.8463), Oceanobacillus (6.9927), and Rummeliibacillus (5.7417). The results indicated that the Pianka measurement values of the spatial ecological niche overlap between any two Bacillus-like genera ranged from 0.00-0.99, some of them had a high overlap, such as Gracilibacillus and Ammoniibacillus, while some of them had almost no overlap, such as Desulfuribacillus and Aneurinibacillus. Moreover, there existed a relationship between the ecological niche breadth and ecological niche overlap:the genera with a wide ecological niche breadth, such as Bacillus, had niche overlap values from 0.20-0.80 with the other genera, while those with a narrow ecological niche breadth, such as Geobacillus, had niche overlap values under 0.20 or over 0.80.
  • DownLoad:Characteristics of the spatial ecological niche of Bacillus-like genera in a microbial fermentation bed used for pig raising.PDF
  • Visualization of Knowledge Maps in the Field of Domestic Ecological Engineering Based on CiteSpaceV
  • Authors:
  • Abstract:Ecological engineering is an important part of ecological civilization construction, Using CitespaceV literature visualization analysis tool, we conducted relevant research on the literature of ecological engineering in Chinese core periodicals and CSSCI periodicals of the Chinese Academic Journals Network Publishing Bank from 1992 to 2017, and plotted the knowledge maps of the research authors, research institutions, and research hotspots. Analyze the research status of domestic eco-engineering projects and discuss and discuss hot topics in the current field, aiming at providing reference for China"s eco-engineering research. Research shows that: (1) Research in the field of domestic ecological engineering began blowout growth in 1997, and began to fluctuate after 2000. (2) Miao Zehua, Yan Jingsong, and ZuoYuhui are scholars with a large number of articles. However, there are few contacts among scholars, which is not conducive to the development of the field. (3) The Shijiazhuang College of Economics, the Institute of Geographic Sciences and Natural Resources Research of the Chinese Academy of
  • DownLoad:Visualization of Knowledge Maps in the Field of Domestic Ecological Engineering Based on CiteSpaceV.PDF
  • Bibliometric assessment of international seagrass research using the web of science database
  • Authors:
  • Abstract:Seagrass and seagrass meadow ecosystems and their adjacent environment are important parts of the offshore marine ecosystem and serve many important ecological service functions. Compared with mangroves and coral reefs, scientists and the public pay less attention to seagrass, and knowledge of the current status, trends, and hotspots gained from international seagrass research are limited. The literature regarding seagrass research was retrieved from the Web of Science's SCI-E database from 1983 to 2017 and bibliometric information visualization analysis methods were applied to conduct a systematic bibliometric assessment of annual publications, research strength, research hotspots, and topics. The goals of this study were to clarify the trends and hotspots of international seagrass research, and to generate valuable reference information for related researchers. The results showed that the amount of international seagrass research literature exhibited an obvious upward trend from 1983 to 2017. The top three countries in this field are the United States, Australia, and Spain. The institution with the most publications was Florida State University, followed by the Spanish National Research Council and National Oceanic (Consejo Superior De Investigaciones Cientificas, CSIC), and the National Oceanic and Atmospheric Administration (NOAA). Authors with a relatively larger total number of publications were Duarte CM, Marba N, and Fourqurean JW; Santos R had the greatest number of publications in the past three years. The most frequently listed journals were the Marine Ecology Progress Series, Aquatic Botany, and Estuarine; Limnology and Oceanography had the highest impact factor (3.969) of the top 15 journals. In cooperation with countries, institutions, and authors, Spain, Denmark, the Netherlands, and Mexico formed a close cooperation network. CSIC and NOAA were two centers in the cooperation network of institutions. Duarte CM, Marba N, and many other scholars exhibited close academic cooperation. The three hot topics of seagrass research were summarized through the analysis of association of high-frequency keywords, and were the effects of environmental stress (pollution) on seagrass meadows, growth and physiological ecology of seagrass, structure and function of seagrass and its related ecosystems. The Chinese Academy of Sciences, Ocean University of China, and other institutions have made important contributions to the study of seagrass in China. Because of the later start of seagrass research, there is a gap between scholars in China and those in European and American countries regarding the number of publications and average citations per article. However, the literatures published in recent years has increased rapidly. It is expected that there will be a strong developmental trend in seagrass research in the future.
  • DownLoad:Bibliometric assessment of international seagrass research using the web of science database.PDF

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