Browsing by Author "Xiao, Yi"

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    Hidden Loss of Wetlands in China.
    (Current biology : CB, 2019-09) Xu, Weihua; Fan, Xinyue; Ma, Jungai; Pimm, Stuart L; Kong, Lingqiao; Zeng, Yuan; Li, Xiaosong; Xiao, Yi; Zheng, Hua; Liu, Jianguo; Wu, Bingfang; An, Li; Zhang, Lu; Wang, Xiaoke; Ouyang, Zhiyun
    To counter their widespread loss, global aspirations are for no net loss of remaining wetlands [1]. We examine whether this goal alone is sufficient for managing China's wetlands, for they constitute 10% of the world's total. Analyzing wetland changes between 2000 and 2015 using 30-m-resolution satellite images, we show that China's wetlands expanded by 27,614 km2 but lost 26,066 km2-a net increase of 1,548 km2 (or 0.4%). This net change hides considerable complexities in the types of wetlands created and destroyed. The area of open water surface increased by 9,110 km2, but natural wetlands-henceforth "marshes"-decreased by 7,562 km2. Of the expanded wetlands, restoration policies contributed 24.5% and dam construction contributed 20.8%. Climate change accounted for 23.6% but is likely to involve a transient increase due to melting glaciers. Of the lost wetlands, agricultural and urban expansion contributed 47.7% and 13.8%, respectively. The increase in wetlands from conservation efforts (6,765 km2) did not offset human-caused wetland losses (16,032 km2). The wetland changes may harm wildlife. The wetland loss in east China threatens bird migration across eastern Asia [2]. Open water from dam construction flooded the original habitats of threatened terrestrial species and affected aquatic species by fragmenting wetland habitats [3]. Thus, the "no net loss" target measures total changes without considering changes in composition and the corresponding ecological functions. It may result in "paper offsets" and should be used carefully as a target for wetland conservation.
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    Reassessing the conservation status of the giant panda using remote sensing
    (NATURE ECOLOGY & EVOLUTION, 2017-11-01) Xu, Weihua; Viña, Andrés; Kong, Lingqiao; Pimm, Stuart L; Zhang, Jingjing; Yang, Wu; Xiao, Yi; Zhang, Lu; Chen, Xiaodong; Liu, Jianguo; Ouyang, Zhiyun
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    Spatial models of giant pandas under current and future conditions reveal extinction risks.
    (Nature ecology & evolution, 2021-07-26) Kong, Lingqiao; Xu, Weihua; Xiao, Yi; Pimm, Stuart L; Shi, Hao; Ouyang, Zhiyun
    In addition to habitat loss and fragmentation, demographic processes-the vagaries of births, deaths and sex ratio fluctuations-pose substantial threats to wild giant panda populations. Additionally, climate change and plans for the Giant Panda National Park may influence (in opposing directions) the extinction risk for wild giant pandas. The Fourth National Giant Panda Census showed pandas living in 33 isolated populations. An estimated 259 animals live in 25 of these groups, ~14% of the total population. We used individual-based models to simulate time series of these small populations for 100 years. We analysed the spatial pattern of their risk of extinction under current conditions and multiple climate change models. Furthermore, we consider the impact of the proposed Giant Panda National Park. Results showed that 15 populations face a risk >90%, and for 3 other populations the risk is >50%. Of the 15 most at-risk populations, national parks can protect only 3. Under the Representative Concentration Pathway 8.5 climate change scenario, the 33 populations will probably further divide into 56 populations. Some 41 of them will face a risk >50% and 35 face a risk >90%. Although national parks will probably connect some fragmented habitats, 26 populations will be outside national park planning. Our study gives practical advice for conservation policies and management and has implications for the conservation of other species in the world that live in isolated, fragmented habitats.
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    The effectiveness of the zoning of China's protected areas
    (Biological Conservation, 2016-12-01) Xu, Weihua; Li, Xiaosong; Pimm, Stuart L; Hull, Vanessa; Zhang, Jingjing; Zhang, Lu; Xiao, Yi; Zheng, Hua; Ouyang, Z
    Increasing human numbers and aspirations threaten protected areas worldwide. China faces especially strong pressure since many people live inside protected areas. It has sought to balance human needs and conservation goals within them by creating mixed zoning schemes loosely based on UNESCO's Man and the Biosphere Programme. These include strictly-protected core zones, buffer zones allowing limited human use, and experimental zones that examine different land-use options. To test the efficacy of this zoning, we employed field surveys and remote sensing to assess the penetration of agricultural and urban land into 109 national nature reserves in China for 2000 and 2010. Human disturbance was lowest in core zones and highest in experimental zones in both 2000 and 2010. Over this period, 82% of the reserves were unchanged or had decreased human disturbance. Nonetheless, overall human disturbance increased by 7%, 4%, and 5% in the core, buffer and experimental zones respectively. Almost all the increase in the core zone was in four wetland reserves, where human actions converted large areas to agriculture. Some 58% of reserves experienced some human disturbance in core zones in 2010, demonstrating a need for more effective zoning. The findings have broader implications for protected area management globally because they highlight the strengths and weaknesses of zoning for balancing human needs and species conservation.