Assessment Of Extant And Potential Habitats Of Hainan Gibbon (Nomascus Hainanus)

The Hainan gibbon(Nomascus hainanus)belongs to the genus Crested gibbon of the Hylobatidae family and is endemic to China and the most endangered primate in the world,currently only found in the Bawangling area of Hainan Tropical Rainforest National Park in China.The main reason for the endangerment of the Hainan gibbon is the degradation and loss of habitat caused by historical human disturbance,which once reduced its population to 7-8 individuals.In recent years,with increased conservation efforts and the construction of national parks,the population of Hainan gibbons has grown to 36 individuals.However,there is still a lack of quantitative assessment of the quality of existing suitable habitat and potential habitat recovery,making it unclear whether suitable habitat for this species will be able to support a sustainable and effective population growth of Hainan gibbons in the future.This study investigated the composition,home range,habitat and dispersal corrdior of various family groups of Hainan gibbons with the aid of field field surveys,GIS and RS techniques,the MaxEnt model,Linkage-Mapper and field plant sample surveys,in order to assess the quality of the species’ habitat and make some judgements about its population development.The main findings are as follows:(1)The home ranges of each family group were measured using the Minimum Convexity CP(MCP)method,and the membership of each family group was investigated based on the activity loci of the Hainan gibbon population from field tracking surveys.The home range of each family group varied between 1.46-3.48 km2,with each family group requiring approximately 0.5 km2 of home range for each self-feeding Hainan gibbon,and at least 1.5 km2 for a family group(one male,one female and one juvenile).(2)The forest landscape and existing habitat quality in the Bawangling area in 2000 and 2020 were analysed using RS and GIS techniques and the MaxEnt model.The study found that primary forest provided 59.97% of the home range for Hainan gibbons and mixed forest consisting of primary and secondary forest provided 25.97% of the home range for Hainan gibbons.Only 18.45 km2 of high suitability habitat and27.19 km2 of secondary habitat existed for Hainan gibbons,of which80.67% of the home range was in high suitability habitat and 18.29% was in secondary habitat;(3)The connectivity of suitable habitat for Hainan gibbons was assessed based on the connectivity index(PC)and(IIC)values and the patch importance index(d PC).The results show that the PC and IIC values are lower than the mean value of 0.5 when the dispersal distance threshold is less than 1 km.d PC values indicate that 85.47% of high suitable habitat plays an important role in habitat connectivity,and therefore the connectivity between suitable habitats for Hainan gibbons is extremely fragile and fragmented at present;(4)The results of the ecological corridor simulations indicate that there are currently three dispersal responses that allow for population dispersal of Hainan gibbon populations A,B and C.The dispersal corrdior of Hainan gibbons consist mainly of secondary forests in the successional to young(25-60 years)stages.The above study helps to supplement and improve the basic information on the membership of each family group of Hainan gibbons and the needs of the home range,which is important for expanding suitable habitats for Hainan gibbons,building natural forest corridors for Hainan gibbons and achieving population growth of Hainan gibbons,as well as providing reference for habitat surveys and ecological corridor construction for primates.