基于青冈和滇青冈生态位模拟的湿润和半湿润常绿阔叶林替代分布及气候解释

Displacement distribution and climate explanation on humid and semi-humid evergreen broadleavedforests using niche model of Cyclobalanopsis glauca and C. glaucoides in China

关键词:  青冈, 滇青冈, 湿润常绿阔叶林, 半湿润常绿阔叶林, 生态位模拟, 替代分布

Key words:  Cyclobalanopsis glauca, C. glaucoides, humid evergreen broadleaved forest, semi-humid evergreen broadleaved forest, niche model, displacement distribution

摘要:

为揭示湿润常绿阔叶林和半湿润常绿阔叶林替代分布的气候制约变量,该研究选择其代表性优势树种青冈(Cyclobalanopsis glauca)和滇青冈(C. glaucoides)为研究对象,收集两个物种的标本分布点数据和19个生物气候变量图层数据,运用MaxEnt模型,模拟其潜在分布区,通过判别分析(DFA)、方差分析(ANOVA)和核密度分析三种方法量化两个树种的生态位差异,解释两类植被地理替代分布规律及其主导气候变量。结果表明:(1)青冈和与滇青冈MaxEnt拟合的AUC值分别为0.995和0.986,准确预测了两物种的潜在分布; 青冈适宜于20°～30° N的亚热带及北热带地区,滇青冈集中分布于云贵高原亚热带区域。(2)DFA和ANOVA的结果一致,表明昼夜温差月均值(bio2)、等温性(bio3)、降水季节性变化(bio15)是造成二者生态位分异的主导气候变量。(3)核密度分析显示昼夜温差月均值(bio2)、等温性(bio3)、温度季节性变动系数(bio4)是影响两物种生态位分化的主导温度变量; 降水季节性变化(bio15)、年降水量(bio12)、最干月降水量(bio14)、最干季降水量(bio17)、最冷季降水量(bio19)是两物种生态位分化的主导降水变量。上述结果说明等温性、温度季节性变化、降水季节性变化等表征气候季节性差异的变量是造成湿润与半湿润常绿阔叶林出现替代分布的主要原因。

Abstract:

To explain the geographical displacement law and the dominant climate variables between humid evergreen broadleaved forests(HEBF)and semi-humid evergreen broadleaved forests(SHEBF), Cyclobalanopsis glauca and C. glaucoides were selected as research objects because the both species are the typical dominant tree species of the HEBF and SHEBF, then the specimens data of the both species and the 19 bio-climate variables map layer were collected to simulate their distribution area using MaxEnt model. Moreover, the niche differences were quantitatively analyzed by the kernel density analysis, discriminant function analysis(DFA)and analysis of variance(ANOVA)to reveal the dominant climate variables which affect the niche differentiation between the both species, then the geographical displacement law and the dominant climate variables between the HEBF and SHEBF were analyzed. The results were as follows:(1)The AUC values of C. glauca and C. glaucoides were 0.995 and 0.986 respectively, which accurately predicted the potential distribution of the both species; C. glauca was suitable for the subtropical and north-tropical regions of 20°to 30° N, but C. glaucoides was mainly distributed in subtropical area of Yunnan-Guizhou Plateau.(2)The results of DFA and ANOVA were consistent, and the mean diurnal range(bio2), isothermality(bio3)and the precipitation seasonality(bio15)were the climate variables that promoted the niche differentiation of the two species.(3)Kernel density analysis showed the mean diurnal range(bio2), isothermality(bio3)and temperature seasonality(bio4)were the dominant temperature variables affecting the niche differentiation of the both species; and the precipitation seasonality(bio15), annual precipitation(bio12), precipitation of the driest month(bio14), precipitation of the driest quarter(bio17)and precipitation of the coldest quarter(bio19)also significantly affected the niche differentiation of the both species. All the above results indicate that isothermality, the seasonal differences of temperature and precipitation are the main variables determining geographical displacement distribution of the HEBF and SHEBF from the niche simulation of C. glauca and C. glaucoides.