海南热带雨林特有兰科植物华石斛潜在适宜生境预测

Prediction of Potential Suitable Habitat of Dendrobium sinense, an Endemic Orchid Species in Hainan Tropical Rainforest

摘要:

为探明华石斛(Dendrobium sinense)潜在适宜分布范围，运用地理信息系统GIS技术和MaxEnt模型，基于25个野外调查的分布数据，以气候变量和地形变量为环境预测因子，对华石斛当前及未来时期的适宜生境进行预测。结果表明，华石斛在海南岛内的潜在适宜生境面积约为403.4 km²，占海南岛总面积的1.1%，主要分布于海南热带雨林国家公园霸王岭分局、鹦哥岭分局、尖峰岭分局、吊罗山分局以及五指山分局管辖区域，零星分布于黎母山分局管辖区、五指山市南部、琼中县、万宁市、保亭县和三亚市等地。华石斛适宜分布区域极其狭窄，适宜生境斑块化，呈现较为严重的破碎化。海拔、降水量季节性变异系数、最湿季降水量及最暖月最高温是影响华石斛种群分布格局的主要环境因子，华石斛的最适宜生境条件为海拔1 070~1 600 m，降水量季节性变异系数0.80~0.88，最湿季降水量1 700~2 266 mm，最暖月最高温18 ℃~25 ℃。相比于当前，2050年在RCP4.5、RCP8.5气候情景下，华石斛的潜在适宜生境分别减少19.1%和19.5%，2070年减少19.7%和19.8%。预测模型的3个评估指标(AUC=0.997±0.003，Kappa系数=0.990±0.03，TSS=0.990±0.03)表明该模型具有较好的预测能力。目前华石斛种群主要分布于海南热带雨林国家公园内，需加强就地保护，同时兼顾对其附生宿主树的保护；猕猴岭东北部及南部、鹦哥岭南部存在大片非常适宜和高度适宜生境，可作为华石斛未知种群调查的重点区域。

Abstract:

To explore the potential suitable distribution range of Dendrobium sinense, its current and future suitable habitat based on the distribution data of 25 field surveys, with climate variables and topographic variables as environmental predictors were predicted by using GIS technology and MaxEnt model. The results showed that the potential suitable habitat area of D. sinense in Hainan Island was approximately 403.4 km², accounting for 1.1% of the total area of Hainan Island. It was mainly distributed in the jurisdiction of Bawangling Branch, Yinggeling Branch, Jianfengling Branch, Diaoluoshan Branch and Wuzhishan Branch of Hainan Tropical Rainforest National Park, with scattered distribution in the jurisdiction of Limushan Branch, the southern part of Wuzhishan City, Qiongzhong County, Wanning City, Baoting County, and Sanya City. The suitable distribution area of D. sinense was extremely narrow, and the suitable habitat was patchy, showing more serious fragmentation. Altitude, coefficient of variation of precipitation seasonality, precipitation in the wettest quarter and maximum temperature in the warmest month were the main environment factors affecting the population distribution pattern of D. sinense. The most suitable habitat for D. sinense was at an altitude of 1 070-1 600 m, with the coefficient of variation of precipitation seasonality of 0.80-0.88, precipitation in the wettest quarter of 1 700-2 266 mm, and the maximum temperature of 18 ℃-25 ℃ in the warmest month. Compared with the current, the potential suitable habitat under RCP4.5 and RCP8.5 climate scenarios of D. sinense decreased by 19.1% and 19.5% in 2050, and 19.7% and 19.8% in 2070, respectively. From three evaluation indexes (AUC=0.997±0.003, Kappa coefficient= 0.990±0.03, TSS=0.990±0.03), the prediction model had good prediction ability. At present, Dendrobium sinense populations are mainly distributed in Hainan Tropical Rainforest National Park, so it is necessary to strengthen in situ conservation and epiphytic host tree protection. There are large areas of highly suitable habitat in the northeast and south of Mihouling, as well as south of Yinggeling, making them as focus region for investigating unknown D. sinense populations.