气候变化对巨柏适宜生境分布的潜在影响和预测

Prediction of suitable habitat distribution and potential impact of climate change on distribution patterns of Cupressus gigantea

随着全球气候变化,植物的生长和生存模式均受到影响。预测气候变化下物种潜在的地理分布范围变化,是判断该物种如何响应气候变化的重要手段,有助于制定科学的物种保护策略。巨柏(Cupressus gigantea)是雅鲁藏布江中游末段及主要支流尼洋河近江河段河岸带的特有物种,也是国家一级重点保护植物,其分布范围主要在朗县至米林市丹娘乡的雅鲁藏布江两岸及尼洋河河谷的巨柏公园,生存受到区域自然资源开发和气候变化的明显影响。该研究基于巨柏当前地理分布数据､地形因子､当前及未来气候条件下的环境因子数据,利用最大熵(MaxEnt)模型､广义线性模型(GLM)和广义相加模型(GAM)与ArcGIS空间分析分别对西藏当前及未来2081-2100年2种气候变化情景(高排放模式SSP5-8.5和低排放模式SSP1-2.6)下的巨柏生境适宜性进行模拟分析。研究结果表明:(1)巨柏的潜在地理分布范围较狭窄,适生区集中分布在加查县至米林市的雅鲁藏布江两岸和米林市至工布江达县的尼洋河两岸,在隆子县､贡嘎县､错那县等地呈零星分布;(2)对巨柏潜在地理分布影响较大的环境因子有最冷季平均气温、温度季节性、昼夜温差月均值和海拔,适宜范围分别为-1.62-2.14℃､565.29-603.78、11.66-12.97℃和2898-3550 m;(3)三种模型模拟结果均表明与潜在地理分布面积相比,未来气候变化情景下巨柏的总适生区面积呈现扩大的趋势,且SSP5-8.5情景下巨柏适生区面积的扩增程度明显高于SSP1-2.6气候情景;(4)与当前适生区质心相比,未来情景下的巨柏适生区质心整体呈向西南偏移的趋势,巨柏的分布区也呈向藏西南雅鲁藏布江中游方向较高海拔迁移的趋势。该研究探究了巨柏生长的关键影响因子及巨柏对气候的响应状况,对巨柏保护具有十分重要的科学意义和实践指导价值。

Aims The growth and survival patterns of species might be affected by global climate change.Predicting changes of the potential range of geographic distribution for a certain species under climate change is important to understand the response of the species to climate change,and helps to formulate scientific conservation strategies for the species.Cupressus gigantea is an endemic species of both the Yarlung Zangbo River and one of the first class National Protection Wild Plants.However,this species faces dual pressures from resource development and climate change.We here research the distribution pattern on the both side of the Yarlung Zangbo River from Nang County to Danniang Town of Nyingchi.Methods In this investigation,we simulated the habitat suitability of C.gigantea under current and two climate change scenarios from 2081 to 2100(SSP5-8.5:high emission scenario and SSP1-2.6:low emission scenario)in Xizang by using maximum entropy models(MaxEnt),generalized liner models(GLM)and generalized additive models(GAM)with ArcGIS spatial analysis based on the current actual geographical distribution information.All the data were obtained by field investigation,with topographic factor variables and environmental data being collected or predicted under current and future climatic conditions,respectively.Important findings The results of the study show that:(1)The potential geographical distribution of C.gigantea was narrow,with the suitable distribution areas beings concentrated in Gyaca County to Gongbo’gyamda County,through which the Yarlung Zangbo River in Xizang.And others were scatterly distributed in LhünzêCounty,Gonggar County,and Cona County in eastern Xizang.(2)Environmental factors which had significant impacts on the potential geographic distribution of C.gigantea were the average air temperature of the coldest quarter,temperature seasonality,mean of monthly(maximum temperature-minimum temperature),and altitude with suitable ranges of-1.62-2.14°C,565.29-603.78,11.66-12.97°C and 2898-3550 m,respectively.(3)The general suitable area of C.gigantea under future climate change scenarios tended to expand compared with the potential geographic distribution area,and its expansion of the suitable area range of C.gigantea under the SSP5-8.5 climate scenario was much higher than the SSP1-2.6 climate scenario.(4)The center of mass in the future scenario displayed an overall trend to the southwest,and the distribution area of C.gigantea also showed a trend to the southwest of the middle reaches of the Southwest Yarlung Zangbo River.Our findings provided the scientific significance and practical guidance for investigating key environmental factors for the growth,restoration and conservation of C.gigantea.