下垫面因素对喀斯特地区水分利用效率的影响

水分利用效率是衡量陆地生态系统对气候变化响应的重要指标,而下垫面因素通过影响局部气候进而影响水分利用效率。喀斯特地区生态缺水严重且下垫面情况复杂,但目前该区域多个下垫面因素对水分利用效率的综合影响仍不明晰。论文利用MODIS GPP和ET数据集计算中国西南喀斯特地区的水分利用效率,结合岩性组合、土壤类型、土地利用类型及地表粗糙度,采用广义线性模型,揭示了下垫面因素对水分利用效率的综合影响。结果表明：研究区水分利用效率受海拔和喀斯特发育程度综合影响,在空间上从东南向西北逐渐升高。下垫面因素中岩性组合对水分利用效率的影响表现出了喀斯特与非喀斯特地区的差异,喀斯特地区的碳酸盐岩岩性组合对水分利用效率呈负向影响,纯喀斯特岩性组合比非纯喀斯特岩性组合负向影响更强;土壤类型对水分利用效率的影响受分布海拔高度差异、土壤有机质差异及喀斯特与非喀斯特地貌差异3种因素影响;土地利用类型总体上呈植被越茂盛的地类对水分利用效率的正向影响越强的趋势;地表粗糙度的增大先对水分利用效率趋正向影响,后趋于负向影响。碳酸盐岩影响土壤性质,而土壤性质和地表粗糙度共同影响植被来对喀斯特地区的水分利用效率产生综合影响。

Effect of underlying surface factors on water use efficiency in the karst area

Water use efficiency (WUE) is an important indicator of terrestrial ecosystem response to climate change, and underlying surface factors affect WUE by influencing local climate. Ecological water shortage in the karst area is serious and the underlying surface is complex, but the comprehensive influence of multiple underlying surface factors on WUE is still unclear. In this study, MODIS gross primary productivity (GPP) and evapotranspiration (ET) data sets were used to calculate WUE in the karst area of Southwest China. Coupled with lithology combination, soil type, land use type, and surface roughness, the generalized linear model was used to reveal the comprehensive influence of underlying surface factors on WUE. The results show that: the WUE of the study area is affected by altitude and karst development degree, and increases from southeast to northwest. Among the underlying surface factors, the impact of lithology combination on WUE shows a difference between karst and non-karst areas. The lithology combination of carbonate rock in the karst area has a negative impact on WUE, and the negative impact of pure karst lithology combination is stronger than that of non-pure karst lithology combination; the impact of soil type on WUE is affected by the difference of distribution altitude, soil organic matter difference, and karst and non-karst landform difference; the impact of land use types generally shows a trend that more densely vegetated land use types have a stronger positive impact on the WUE; the increase of surface roughness first has a positive impact on the WUE, and then tends to have a negative impact. Carbonate rocks affect soil properties, and soil properties and surface roughness jointly affect vegetation.