基于MaxEnt的四川省红豆杉潜在分布区分析及适宜性评价

Predictive Distribution and Habitat Suitability Assessment of Taxus chinensis Based on MaxEnt in Sichuan Province

以四川省全国第二次重点保护野生植物资源调查中201个红豆杉分布点为基础数据源,筛选31个影响红豆杉分布的环境变量,应用Max Ent最大熵模型,结合Arc GIS地理信息系统,划定四川省红豆杉潜在分布区并进行适宜性评价,结果表明:(1)红豆杉在四川省的最适生区域面积11 508.750 89 km^2,占全省面积2.37%;适生区域面积13 340.487 64 km^2,占全省面积2.75%;较适生区域面积12 099.527 38 km^2,占全省面积2.49%;不适生区域面积448 368.743 5 km^2,占全省面积92.39%;最适生、适生及较适生区域主要位于茶坪山、龙门山、大巴山、华蓥山、大娄山、大相岭及邛崃山等盆周山地边缘;(2)31个影响红豆杉分布的环境变量中,海拔、年均温、7月降水量、昼夜温差月均值、最冷季度平均温度、降水量变异系数、最冷月最低温、坡度、3月光照强度、7月平均温度、最干季平均温度及11月平均温度是对红豆杉分布有主要影响的12个环境变量;(3)红豆杉最适生环境为气候较为温暖,年均温7.5℃~15℃,昼夜温差月均值7℃~10℃;海拔1 000 m^2 400 m;降水量充沛,7月降水量50 mm^160 mm,降水量变异系数50~75;光照充足,3月光照强度11 000 KJ·m-2·d-1~12 200 KJ·m-2·d-1的亚热带地区,植被覆盖率较高的山沟或山林中。

The 201 localities of Taxus chinensis were selected as the underlying data source found in the second national survey of key wild plant resources in Sichuan. A total of 31 environmental variables were screened that affect the distribution of Taxus chinensis. The potential distribution areas of Taxus chinensis in Sichuan were designated and their suitability was evaluated by using the maximum entropy model( Max Ent) and the Arc GIS geographic information system. The results have indicated that(1) the most suitable area size for the growth of Taxus chinensis in Sichuan is 11 508. 750 89 km^2,accounting for2. 37% of the total area of Sichuan; the suitable area size for the growth is 13 340. 487 64 km^2,account-ing for 2. 75%; the relatively suitable area is 12 099. 527 38 km^2,accounting for 2. 49%; and the unsuitable area size is 448 368. 743 5 km^2,accounting for 92. 39%. The area which is the most suitable,suitable and relatively suitable for the growth of Taxus chinensis is mainly distributed at the edge of the mountain regions around the Sichuan Basin,such as Chaping Mountains,Longmen Mountains,Daba Mountains,Huaying Mountains,Dalou Mountains,Daxiangling Mountains and Qionglai Mountains;(2) Among the 31 environment variables which have influence on the distribution of Taxus chinensis,12 of them have the major impact. To be specific,these major variables are altitude,annual temperature,precipitation in July,the monthly mean diurnal tempereture range,the average temperature in the coldest month,the precipitation variation coefficient,the lowest temperature in coldest month,the slope,the solar radiation in March,the average temperature in July,the average temperature in the driest season and the average temperature in November;(3)The most suitable environment for Taxus chinensis is highly vegetated subtropical ravine comparatively warm climate of 7. 5 ℃ ~ 15 ℃ in annual mean temperature,and 7 ℃ ~ 10 ℃ in mean diurnal range,altitude of 1 000 meters ~ 2 400 meters,abundant 50 mm ~ 160 mm precipitation in July with a 50 ~ 75 variation coefficient,solar radiation of 11 000 KJ·m-2·d-1 to 12 200 KJ·m^(-2)·d^(-1).