华北农牧交错带农田-草地景观镶嵌体土壤水分空间异质性

Abstract

PDF HTML阅读 XML下载 导出引用 引用提醒 华北农牧交错带农田-草地景观镶嵌体土壤水分空间异质性 DOI: 10.5846/stxb201306091519 作者: 作者单位: 宁夏大学 农学院,宁夏大学 农学院,中国农业大学 动物科技学院 北京,宁夏大学 农学院,宁夏大学 农学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然基金资助项目(31060325) Spatial heterogeneity of soil moisture across a cropland-grassland mosaic：a case study for agro-pastural transition in north of China Author: Affiliation: NingXia University,,,, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:为揭示草地景观破碎化过程中产生的农田-草地镶嵌体内部土壤水分空间异质性、分布格局以及生态界面特征,本研究利用经典统计与地统计学方法对华北农牧交错带农田-草地镶嵌体不同采样粒度(0.5 m×0.5 m,1 m×1 m,2 m×2 m)土壤水分空间异质性进行分析。结果表明:农田-草地镶嵌体内部土壤水分含量差异显著表现为农田>农田-草地边界>草地 (P < 0.05);土壤水分变异系数(CV Coefficent of variation)差异显著表现为农田-草地边界>草地>农田(P < 0.05),均属中等程度变异。在农田-草地镶嵌体尺度下,农田-草地边界土壤水分在3个采样粒度下均拟合为球状模型,空间异质性大小(MSH Magnitude of spatial heterogeneity)分别为0.814、0.763和0.883,变程为15.44、27.24和19.09 m,属强空间自相关;草地土壤水分空间异质性在3个采样粒度下拟合呈指数和球状模型,空间异质性大小分别为0.537、0.837和0.650,变程分别为6.009、12.74和30.99 m,属中到强空间自相关;农田土壤水分在采样粒度2 m×2 m下拟合成球状模型,空间异质性大小为0.706,变程27.28m,属中等空间自相关,而在较小采样粒度下均为纯金块效应(Nugget)呈完全随机分布,即不同采样粒度(0.5 m×0.5 m,1 m×1 m,2 m×2 m)的农田、农田-草地边界、草地的土壤水分空间异质性大小存在显著差异且表现为农田-草地边界>草地>农田(P < 0.05),同时每种类型不同采样粒度间的空间异质性大小存在差异但无线性关系(P > 0.05);农田-草地镶嵌体内部的农田-草地边界土壤水分分布格局异质程度高,呈明显斑块状,而农田内部土壤水分较草地更加破碎匀质化,同时土壤水分在农田-草地边界处表现为伴有突然升高随即降低剧烈变化的界面效应。 Abstract:As a direct consequence of greater landscape fragmentation worldwide, it is becoming increasingly common for agricultural landscapes to be dissected by boundaries between crop types. However, our understanding of processes associated with these boundaries remains comparatively undeveloped. Cropland-grassland mosaics resulting from intensification of farming activity on extensive grassland are now common in north of China. These land use changes not only influence the original ecosystem processes but also generate new ecological processes that impact on the regional environment at a larger scale. Recently the topic of spatial heterogeneity of soil moisture has received more attention from ecologists because it plays an important role in the hydrological cycle through effects on the interaction between land and atmosphere, thus climate and plant growth in different ecological scales. Despite this emerging focus few studies have examined the spatial heterogeneity of soil moisture in cropland-grassland mosaics in north of China. Here we report data investigating the spatial pattern for soil moisture variation in cropland (C), the cropland-grassland boundary (B) and grassland (G) of a cropland-grassland mosaic. The scale of heterogeneity for soil moisture was assessed by evaluating sampling units of differing sizes (0.5 m×0.5 m, 1 m×1 m, 2 m×2 m) using classical statistical and geostatistical methodologies. Soil water content of C was significantly higher than that of G (P < 0.05). Soil water content of B was intermediate between C and G and differed significantly from both C and G (P < 0.05). The B zone displayed a higher coefficient of variation (CV) for soil moisture than the adjacent systems (P < 0.05), The geostatistical analysis determined that values of the magnitude of spatial heterogeneity (MSH) for soil moisture for B were 0.814, 0.763 and 0.883, respectively, in the three sampling grain sizes (0.5 m×0.5 m, 1 m×1 m, 2 m×2 m). There was also a strong autocorrelation with the ranges A0 15.44, 27.24 and 19.09 m, respectively. The MSH values of soil moisture for G were 0.537, 0.837 and 0.650, and there was a moderate to strong autocorrelation with the ranges A0 6.009, 12.74 and 30.99 m, respectively, in the three different sampling grain sizes. The MSH of soil moisture for C was 0.706, which had a moderate autocorrelation with range 27.28 m in grain size 2 m×2 m, whereas there were nugget effects at the other finer sampling grain sizes. The MSH of the cropland-grassland mosaic displayed a nonlinear relationship across different sampling scales in the field. We found soil moisture for B displayed the highest spatial heterogeneity (i.e. significant patchiness), whereas the soil moisture for C was more homogeneous in comparison with soils under grassland. With respect to the characteristics of the B transition zone, there was an abrupt change of increase then rapidly decreases for soil moisture from cropland to grassland in the cropland-grassland mosaic. The data therefore support the ‘ecological boundary effects’ hypothesis that the ecological boundary is more heterogeneous than that of the adjacent systems and also show that abrupt ecological boundary effects occur. Our results suggest that the historical shift from perennial herb to monocrop culture in grasslands ecosystem led to changes in the small-scale spatial structure of soil moisture and related processes. These changes in land utilization may therefore alter ecosystem function and further impact the regional climate. 参考文献 相似文献 引证文献