| The hilly Loess Plateau is one of the most serious soil erosion areas in Loess Plateau.The Chinese government has launched several projects at various scales.The revegetation cover has substantially increased and has effectively controlled soil erosion in this region since the project of the Grain-for-Green Program,aiming to control soil erosion and improve environmental conditions,was initiated in 1999.Nevertheless,the large-scale conversion of cropland to forest has brought new problems in this area,such as biomass overload and excessive water consumption.The vegetation there continues to degrade because the revegetation does not match the site environment.To this end,it is necessary to evaluate the adequacy of current potential vegetation pattern and propose a reasonable revegetation plan.Accordingly,adjusting the vegetation structure as well as rearranging a reasonable layout has become an ideal choice for sustainable restoration of the area and alleviation of excessive restoration in some areas.The Near-Nature restoration mode has been used in revegetation planning all over the world.The Near-Nature theory restore the degraded ecosystem to an ecosystem with species composition,diversity,and community structure close to natural communities based on the ecological theory,through scientific and effective artificial assistance and management measures,relying on natural ecological processes.The structure of the restored ecosystem has functional diversity,stability and sustainability.In this study,the Yanhe River catchment covers an area of 7687km2 and located in the Hilly Loess Plateau Region was used as the research area.The study period was from 2016 to 2019.The goal of this study is to analyze the relationship between the distribution of native species and the response of environmental factors.Besides,this study measures the variation characteristics of functional traits.The suitability relationship with species distribution was discussed in depth,and priority restoration areas were identified based on the appropriate habitat suitability pattern in this area.The main conclusions obtained are as follows:(1)This study demonstrate that Temsea is the most important factor affecting the geographical distribution,and the SloD is the second most important factor affecting geographic distribution of the contribution rate of 13 environmental variables to the model.The SloD contributes more than 5%to the geographic distribution of 43 native species,which occupied an important position in the distribution of 11 species(>15%).Overall,it is shown that in the study of small-scale vegetation habitat suitability,the influence of climate and topographic factors on species distribution cannot be ignored.(2)The study on the habitat suitability of different vegetation types in this area show that the potentially suitable habitats for shrubs were larger than that of the forest,and herbaceous were distributed in many zones of the study area;the potentially suitable habitats for forest cover were distributed in the southern part of the Yanhe River catchment and the suitable areas were the narrowest and fragmented;the potentially suitable habitats for herbaceous were located in the center and the northwest parts of the study area which were the largest and concentrated.This study demonstrated that shrubs and herbaceous plant species in parts of the loess hilly area should be considered as the pioneer plants of revegetation in future revegetation plans.Moreover,the habitat suitability of native plants located in the middle of the study area such as Yan'an and An' sai in the assessment of the distribution pattern of habitat suitability.(3)In the correlation analysis of plant functional traits and the distribution layout of species habitat suitability,the results demonstrate that:the coefficient of variation about specific leaf area was significantly positively correlated with the suitability distribution of species suitability in the Yanhe River catchment,while the variation characteristics of other functional traits were not significantly correlated with the distribution of species suitability.Therefore,the coefficient of variation of specific leaf area is more suitable as a trait indicating the size of herbaceous species suitable area in the Yanhe River catchment.This research will provide references for vegetation restoration and construction and ecological sustainable management strategies.(4)This study identified the near-natural restoration priority areas in the Yanhe River catchment used the Prioritizr package.The denser priority restoration areas are in the central and southern parts of the study area and the Ansai county. |
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