Spatial distribution of endangered orchids in the Yangtze River Watershed

Key words: 
• Yangtze River watershed /
• Orchidaceae plants /
• spatial autocorrelation /
• kernel density /
• distribution pattern

Abstract:   Objective  This study, with an investigation of the scientific and standard identification of the migration of Orchidaceae, a protected and flagship group, in the Yangtze River Watershed, is aimed at an exploration of the spatial distribution of endangered orchids and the determination of key protected species and hot spots so as to serve the better research and protection of rare and endangered orchids.   Method  Taking the representative Orchidaceae plants in the Yangtze River Watershed from 1981 to 2019 as the research object, 130 species distribution points of 10 species including Neottianthe and Pleione were selected based on the field investigation and Global Biodiversity Information Facility (GBIF) database. Then, with the guidance of the theory of phytogeography and the conduct of a GIS spatial analysis, the spacial distribution of endangered orchids was investigated employing kernel density, Moran index and hot spot distribution.   Result  (1) The period between 1998 and 2019 witnessed the disappearance of Orchidaceae plants in Guangxi and Guizhou, a decrease in high-density areas of them in the Yangtze River Watershed, changes in the median density areas as well as their migration from central Sichuan to north Sichuan. (2) There was a significant positive correlation between the level of endangerment of Orchidaceae plants and their spatial location and the correlation between 1998 and 2019 was stronger than that of 1981−1997. (3) There was a shift of high risk areas: from 1981 to 1997, the high risk areas of Orchidaceae were mainly distributed in Guizhou and Hubei whereas from 1998 to 2019, they were mainly distributed in Hubei Province.   Conclusion  There have been changes in the distribution of Orchidaceae plants and a reduction in quantity which mainly attribute to global warming, infrastructure construction, illegal harvesting and excessive deforestation and in the future Hubei would become the focus of attention. [Ch, 1 fig. 5 tab. 31 ref.]