干热河谷不同土地利用类型坡面土壤水分时空变异

Spatial and Temporal Variability of Soil Moisture on Sloping Lands of Different Land Use Types in a Dry-hot Valley

为探究干热河谷区不同土地利用类型坡面土壤水分的时空变化规律,以元谋干热河谷老城小流域水土保持综合治理示范区内的银合欢人工林地、扭黄茅草丛地和坡耕地为研究对象,采用经典统计学和地统计学克里格插值相结合的分析方法,对3种土地类型坡面土壤水分的时间和空间异质性进行研究。结果表明:元谋干热河谷区土壤含水量较低(林地旱季7.56%,雨季12.80%;草地旱季8.05%,雨季12.66%;坡耕地旱季19.37%,雨季22.95%),雨季显著大于旱季。旱、雨季均表现为坡耕地>草地>林地,呈中等至强度变异(0.14~0.72之间);不同土地利用类型下各层土壤水分的自相关系数均由正向负转化的相同趋势,但拐点有所不同,且雨季大于旱季;不同土地利用类型下旱、雨季土壤水分的最佳拟合模型林地与草地相同(林地与草地旱雨季均为球状模型,坡耕地旱雨季为指数模型),均呈中等或强等空间相关性(0.05~0.39之间),且旱季大于雨季;同一土地类型下旱、雨季不同土层的土壤水分空间分布相似,不同土地利用类型下相同土层分布格局则不同。

In order to investigate the temporal and spatial variation of soil moisture in the dry-hot valley, a study was carried out in the demonstration area of soil and water conservation in the old town village of Yuanmou, taking the Leucaena leucocephala plantation, Twig grassland and sloping land as the research objects, by combining classical statistics and geostatistics analysis methods, the spatial and temporal variability of soil moisture on sloping lands of three land use types were studied. The results showed that： Soil water content in Yuanmou in the dry-hot valley was low （which was 7.56% and 12. 80% in the dry and rainy season of forest land, 8.05% and 12.66 in the grassland, and 19.37% and 22.95% in the farmland, respectively）, soil moisture in the rainy season was significantly higher than that in the dry season, and followed the order of sloping farmland〉grassland〉forest land in both the dry and rainy seasons, and showed moderate variation （between 0. 14 to 0. 72）; the autocorrelation coefficients of soil water content in different layers of soil of different land use types all showed a positive to negative transformation trend, but the inflection point was different. The autocorrelation coefficients in the rainy season were higher than those in the dry season, the best fitting model for the forestland and grassland of soil moisture in the dry and rainy season were the same for different land use patterns （both the forest and grassland were spherical models during the rainy and dry season, and the farmland was the exponential model in the dry and rainy season）, and all showed moderate or strong spatial correlation （between 0.05 and 0.39）, which was greater in the dry season than in the rainy season. The spatial distribution patterns of soil moisture in different layers of soil of the same land type were similar in the dry season and rainy season, but the distribution patterns in the same layer of soil of different land use patterns were different.