艾比湖绿洲实际蒸散量变化特征及与景观格局的关系

Variation characteristics of actual evapotranspiration in the Ebinur Lake oasis and its relationship with landscape pattern

基于Budyko曲线方程计算新疆艾比湖绿洲1960—2013年实际蒸散量的年际和季节变化特征,选取研究区四期遥感影像进行土地利用/覆被分类,使用Fragstas 4.2软件计算景观格局指数,并分析实际蒸散量与景观格局指数之间的关系。结果表明:艾比湖绿洲实际蒸散量多年平均值为162.97mm,并呈上升趋势,变化速率为7.76mm·(10a)^(-1);夏季和秋季的实际蒸散量为上升趋势,春季则呈下降趋势;年实际蒸散量在1987年发生突变性增加,夏季和秋季实际蒸散量的突变年份分别为1992年和1975年,春季不存在突变点,这与降水量的突变状况一致,说明降水量的变化对实际蒸散量的变化有很大影响。四期土地利用/覆被图中荒漠占主导地位,耕地和城镇用地增长较为明显,分别增长了409.69%和704.56%。斑块类型级别上,不同地类的景观格局指数差异明显;景观级别上,各景观格局指数均为波动增加趋势。斑块类型级别上,仅有水域斑块数量NP和斑块密度PD与实际蒸散量呈显著负相关;景观级别上,实际蒸散量与最大斑块指数LPI、蔓延度指数CONTAG及景观连通性指数COHESION呈负相关,与斑块数量NP、斑块密度PD等指数呈正相关。实际蒸散量与聚集度指数AI的相关性最高,达到0.953(P<0.05);与NP和PD的相关性最低,仅为0.148。因此,AI指数在艾比湖绿洲可以较好地表征实际蒸散量的变化。

Based on the Budyko curve equation,we calculated interannual and seasonal variation characteristics of actual evapotranspiration in the Ebinur Lake oasis from 1960 to 2013.The four remote sensing images of the study area were selected for land use/cover classification,and the landscape pattern index was calculated with Fragstats 4.2.The relationship between actual evapotranspiration and landscape pattern index shows that:The average actual evapotranspiration in the Ebinur Lake oasis is 162.97 mm,which was an upward trend with a tendency rate of 7.76 mm·(10 a)^(-1);the actual evapotranspiration in summer and autumn was an upward trend,while the spring was a downward trend;the mutation in abrupt increase of annual actual evapotranspiration occurred in1987.As to the seasonal mutation,the abrupt increase of summer and autumn occurred in 1992 and 1975,respectively.However,the actual evapotranspiration in spring did not exhibit mutation.The four periods of land use/cover map show that desert was dominated in the Ebinur Lake oasis,which was more than 50%in area,while cultivated land and urban land had a significant increase,which reached to 409.69%and 704.56%,respectively.Landscape pattern indices showed a significant difference at patch types level,and all landscape pattern indices showed a fluctuate increase at landscape level.At patch types level,the significant correlations were only observed among the actual evapotranspiration with water NP and PD,the correlation coefficient were both-0.981(P<0.05);at landscape level,a negative relationship was observed among the actual evapotranspiration with LPI,CONTAG and COHESION,while a reverse one was among the NP,PD,IJI,SHDI and AI.The largest correlation coefficient was 0.953(P<0.05)between the actual evapotranspiration and AI,while the two lowest correlation coefficient both were 0.148 occurred at NP and PD.This indicated that the AI index can better characterize the variation of the actual evapotranspiration in the Ebinur Lake oasis.