不同类型人工草地小尺度土壤水分空间异质性特征研究

Spatial Heterogeneity of Soil Moisture in Different Artificial Grasslands with Finer Scales

为阐明人工植被与土壤空间异质性的关系,运用经典统计学和地统计学方法对紫花苜蓿（Medicago sativa）、高羊茅（Festuca arundinacea）和串叶松香草（Sil pnium per oliatum）人工草地土壤水分进行0.2m×0.2m,0.4m×0.4m和0.6m×0.6m不同采样粒度测定分析.结果表明：在不同采样粒度下3种人工草地土壤水分变异系数雨前均大于雨后,呈中等变异,雨后均为弱变异,且干旱时土壤水分空间变异性具有显著尺度效应（P＜0.05）.雨前3种人工草地土壤空间异质性存在差异,即：紫花苜蓿草地在采样粒度0.2m×0.2m和0.4m×0.4m下拟合呈球状模型,表现出强空间自相关性（＞75％）,空间自相关距离为0.920～1.130 m;高羊茅人工草地随采样粒度加大表现为从中等到强空间异质性,自相关距离为1.330～4.098 m;串叶松香草人工草地在粒度0.4m×0.4m和0.6m×0.6m下拟合为球状模型,中等空间异质性,自相关距离为3.010～5.009 m;雨后3种人工草地基本表现为纯金块效应（Nugget）.说明土壤干旱时,各采样粒度下的紫花苜蓿、高羊茅和串叶松香草人工草地的土壤水分空间异质性主要由植物个体及种群特征差异影响,而雨后3种人工草地土壤水分空间异质性由于受土壤含水量升高的作用,表现为纯金块效应,呈完全随机分布.

In order to understand the relationship between artificial vegetation and the spatial heterogeneity of soil moisture, three artificial grassland types （Medicago sativa, Festuca arundinacea ,Silpnium perfo- liatum） were investigated using the methods of classic statistics and geostatistics with different grain sizes （0.2 mX0.2 m, 0.4 mX0.4 mand0.6 mX0.6 m） in both arid period and raining period. The results of classic statistics showed that the coefficient of variation （CV） of soil moisture was moderate and higher in arid period than that in raining period. Geostatistics results showed that the spatial heterogeneity of soil moisture in Medicago sativa grassland had a strong spatial dependency （〉75%） and the range A0 was 0. 920-1. 130 meter in the sampling grain sizes of 0.2 mX0.2 m and 0.4 mX0.4 m. The spatial heteroge- neity of soil moisture in Festuca arundinacea grassland increased with the increase of sampling size, and the range A0was 1.33-5. 009 meter. And the spatial heterogeneity of soil moisture in Silpnium perfolia- turn grassland had a moderate dependency and the range A0was 3. 010-5. 009 meter in the sampling grain sizes of 0.4 mX 0.4 m and 0.6 m X 0.6 m. These results demonstrated that the spatial heterogeneities of tested grasslands had nugget effects and no spatial dependency due to the increase of soil water content in raining period.