Vegetation Habitat Suitability Modeling And Climate-change Risk Assessment Of China’s Inland Wetlands

Wetlands are among the most productive ecosystems on our planet,offering crucial ecosystem services to the biosphere and human societies.However,global wetlands are under dire threats from anthropogenic activities and climate change,and risk extensive degradation and loss,which calls for timely climatic risk assessments and the development of climatesmart conservation strategies.Understanding key environmental factors and their contributions to species habitat suitability would benefit wetland conservation efforts,especially in regard to selecting vulnerable species and delimiting priority wetlands in the context of climate change.Ecological niche models(ENMs)are an effective tool for projecting species habitat suitability,but the application of ENMs in wetlands is rare owing to limited survey data.Thus,this study applied and optimized ENMs to investigate the current and future habitat suitability of the dominant plant species to characterize habitat changes and climatic risks across the inland wetland regions of China.Results from this effort are essential for identifying priority areas of wetland conservation,estimating the effectiveness of current conservation projects under climate change,and developing climatesmart conservation strategies.To accomplish the goals,this study drew on a massive dataset including species occurrence records derived from field surveys and herbarium specimens.Linear mixed-effects models combined with numerous environmental predictors were applied to assess the difference in sensitivity to limiting environmental factors among species groups.This study identified that:(1)Among a series of ENM algorithms,machine learning tools(i.e.,Generalized Boosting Model,Random Forest,and MAXENT)presented higher accuracy and stability in modeling species habitat suitability in wetlands.The performance of ENMs used in wetlands could benefit from incorporating soil and topo-hydrological factors in addition to climatic variables and selection of proper spatial resolution that allows for a better depiction in habitats of target species.(2)Climatic(e.g.,isothermality,precipitation of the growing season,precipitation of coldest quarter),soil(e.g.,soil nutrient availability,soil p H),topo-hydrological(e.g.,water table depth,slope),and human-related variables are the key factors driving species habitat suitability in wetlands.The results from linear mixed-effects models showed that species of different types(e.g.,woody/non-woody,annual/perennial)had significant differences in their sensitivity to the key environmental factors.(3)Native wetland species likely face habitat shrinkage under the threat of climate change,especially woody species.In comparison to the moderate warming scenario(RCP4.5),the suitable habitats are less stable,and the habitat loss is more severe under the extreme warming scenario(RCP 8.5).In the meantime,climate change would enhance the suitability of non-wetland species and invasive species,which would facilitate their expansion and invasion in China’s inland wetlands and further change the composition and structure of wetland vegetation communities.(4)Climate change is projected to pose differential regional impacts on the survival of wetland species.Northeast China is a hotspot with most wetland species under high climatic risk in the future.Wetlands of the Middle-Lower Yangtze Plain are also threatened with reduced habitats for native wetland species and predicted expansion of non-native wetland species.Due to the potential improvement in physical conditions,native wetland species of the Tibetan Plateau would experience a distinct expansion of potential habitats,as well as potential encroachment of non-wetland species.(5)There is an apparent mismatch between projected wetland conservation hotspots and current national reserves,and only less than 20% of projected conservation hotspots are currently protected,showing conservation gaps in the existing wetland protection framework.Therefore,incorporating climate change factors into China’s current wetland protection framework and establishing new wetland reserves based on climate change monitoring and climatic risk assessments are key tasks for future wetland management efforts.Based on the results,the study proposes four suggestions for the improvement of China’s wetland protection framework:(1)incorporating the future climatic risks and potential species adaption in regional and national conservation plans;(2)paying more attention to preserving natural wetlands while ensuring no net loss in wetland area;(3)improving the national wetland inventory and monitoring network;(4)incorporating the conservation of small wetlands in the wetland protection framework.