| Plant species with extremely small populations(PSESP)are the national key protected plants in urgent need of priority rescue.Studying the scope and quality of species habitat can provide scientific basis for species protection and resource management.According to the characteristics of PSESP,Maxent model was used to study the potential distribution of Taxus cuspidata under the influence of climate,topography,soil and vegetation factors,and Jackknife cutting method was used to study the environmental variables and factors affecting the potential distribution.The abundance of T.cuspidata was used as the indicator of habitat quality,and the environmental variables used in the distribution study were used as the evaluation factors.Fuzzy mathematics was used to construct a single factor evaluation function.According to the evaluation results of HSI model,the potential distribution area of T.cuspidata was divided into high and low suitable areas.using the same method,Evaluating the degree of direct human disturbance to T.cuspidata made use of population density and distance from road by same method.and the Northeast before and after adding human interference factors.A comparative analysis of habitat quality of T.cuspidata before and after adding human disturbance factors was done.The main conclusions were as follows:(1)T.cuspidata was mainly distributed in Changbai Mountains of Northeast China,showing the characteristics of distribution along the mountainous areas,with a potential area of 57,600 square kilometers,with serious habitat fragmentation and landscape fragmentation index of 0.045.The main environmental factors affecting the potential distribution of T.cuspidata were altitude,vegetation type,isothermality,slope,summer average temperature and soil type.The distribution range of T.cuspidata was mainly restricted by climatic factors on regional scale.The degree of habitat fragmentation was greatly increased by topographic factors on landscape scale,while the influence of vegetation and soil factors were not obvious.(2)Using HSI model and fuzzy mathematics method to evaluate the habitat quality of T.cuspidata was accurate,and AUC value was 0.87.The evaluation results showed that the actual high suitable areas were concentrated in eastern Jilin and southeastern Heilongjiang,with an area of about 108,000 square kilometers.The actual low suitable areas were mainly concentrated in Zhangguangcailing area of Heilongjiang and southeastern Jilin with an area of about 39,000 square kilometers.T.cuspidata showed habitat preference for environmental assessment factors except soil available water capacity and had a clear optimum range.(3)At present,the main form of human disturbance was direct destruction,which caused the average loss the quantity of T.cuspidata more than 30%.About 13.5%potential distribution area of T.cuspidata was reduced by human indirect disturbance.For the protection of T.cuspidata,the public’s awareness of the PSESP should be strengthened first.Secondly,we proposed strategies of in-situ conservation,establishment of conservation plots and near-field conservation depending on the size,dispersion and quality of the habitat patches of potential species distribution,which can be helped with enhanced transplant to improve the quantity and structure of the population. |
