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野桂花和管花木犀的适宜分布区及主要气候变量分析

花匠小妙招
2024-12-28 08:25

摘要

基于野桂花〔Osmanthus yunnanensis （Franch.） P. S. Green〕和管花木犀（O. delavayi Franch.）的分布记录和气候变量，利用MaxEnt模型预测其现代适宜分布区和未来（2070年）潜在适宜分布区，利用贡献率、置换重要值和Jackknife检验评价影响其分布的主要气候变量，并利用限制因子映射工具模拟各分布区主要气候变量的分布模型。结果表明：当正则化参数为0.5、参数组合为线性+二次型（L+Q）时，野桂花和管花木犀MaxEnt模型的AIC值最小，分别为1 170.4和817.9，AUC值最大，分别为0.976和0.948，表明优化参数后的MaxEnt模型预测精度非常高。利用该模型预测的野桂花和管花木犀的现代适宜分布区相似，主要包括四川、云南、广西西部、西藏东南部和贵州西部，其适生区面积分别占中国总面积的3.52％和4.21％，高度适生区面积分别占中国总面积的1.02％和1.14％。在RCP8.5气候情景下，野桂花的未来潜在适宜分布区向东部和北部扩张，适生区和高度适生区的面积分别为8.21％和0.30％；而管花木犀的未来潜在适宜分布区向西部和北部扩张，适生区和高度适生区的面积分别为4.41％和1.10％。依据贡献率、置换重要值和Jackknife检验，影响野桂花和管花木犀分布的主要气候变量均为气温季节性变化、年平均气温和年降水量；并且，在存活概率为0.5时，野桂花适宜分布区3个气候变量的方差范围大于管花木犀，说明野桂花的生态适应范围更广。另外，年平均气温限制了野桂花分布区的东界，年降水量制约其向北移动；年降水量限制了管花木犀分布区的南界。研究结果显示：优化参数后的MaxEnt模型预测结果非常准确，预测的野桂花和管花木犀的现代适宜分布区均为四川、云南、广西西部、西藏东南部和贵州西部，而其未来潜在适宜分布区却存在差异；温度和降水是影响其分布的主要气候变量，但不同分布区的主要气候变量却存在差异。

Abstract

Based on distribution records and climatic variables of Osmanthus yunnanensis （Franch.） P. S. Green and O. delavayi Franch.， their present suitable distribution areas and potential suitable distribution areas in the future （in 2070） were predicted by using MaxEnt model， and the main climatic variables affecting their distributions were evaluated by using contribution rate， permutation importance， and Jackknife test， meanwhile， the distribution models of main climatic variables in each distribution area were simulated by using limiting factor mapping tools. The results show that when regularization parameter of 0.5 and parameter combination of linearity+quadratic type （L+Q）， AIC values of MaxEnt models of O. yunnanensis and O. delavayi are the smallest with values of 1 170.4 and 817.9， respectively， and AUC values are the largest with values of 0.976 and 0.948， respectively， indicating that the prediction accuracy of MaxEnt model after parameter optimization is very high. The present suitable distribution areas of O. yunnanensis and O. delavayi predicted by this model are similar， which mainly include Sichuan， Yunnan， West Guangxi， Southeast Tibet， and West Guizhou， and their areas of suitable distribution area account for 3.52％ and 4.21％ of total area of China， respectively， while their areas of highly suitable distribution area account for 1.02％ and 114％ of total area of China， respectively. Under the climatic scenario of RCP8.5， potential suitable distribution area in the future of O. yunnanensis expands to the east and north， and areas of suitable distribution and highly suitable distribution areas are 8.21％ and 0.30％， respectively； while potential suitable distribution area in the future of O. delavayi expands to the west and north， and areas of suitable distribution and highly suitable distribution areas are 4.41％ and 1.10％， respectively. According to contribution rate， permutation importance， and Jackknife test， main climatic variables affecting distributions of O. yunnanensis and O. delavayi are variation of temperature seasonality， annual mean temperature， and annual precipitation； in addition， variance ranges of three climatic variables of O. yunnanensis in suitable distribution area are greater than those of O. delavayi when survival rate of 0.5， indicating that the ecological adaptive range of O. yunnanensis is wider. Moreover， annual mean temperature constrains the east border of distribution area of O. yunnanensis， while annual precipitation constrains its movement toward north； annual precipitation does the south border of distribution area of O. delavayi. It is suggested that the prediction result of MaxEnt model after parameter optimization is very accurate， and the predicted present suitable distribution areas of O. yunnanensis and O. delavayi are Sichuan， Yunnan， West Guangxi， Southeast Tibet， and West Guizhou， but there is difference in their potential suitable distribution areas in the future； temperature and precipitation are the main climatic factors affecting their distributions， but there are differences in main climatic factors among different distribution areas.