东北黑土区小流域农业景观结构与土壤侵蚀的关系

以黑土侵蚀区的拜泉县双阳河流域为案例，提取地形和土壤类型相对接近的30个上游子流域作为分析样本。以遥感、GIS和FRAGSTATS软件为平台获得景观格局指数，运用基于GIS的RUSLE模拟土壤侵蚀，通过相关性分析和多元回归研究景观指数与侵蚀模数的呼应关系。从而探讨土地利用调整和流域综合治理下的景观结构特征对土壤侵蚀的影响，为当地或同类地区土地利用规划和侵蚀治理提供科学参考。结果表明：顺坡垄农田面积百分比、景观聚集度与土壤侵蚀模数显著正相关，灌木林地、草地面积百分比、香农多样性指数与土壤侵蚀模数显著负相关。9个结构因子与土壤侵蚀模数的复相关系数（R=0．931）大于单因子相关系数，多个景观结构因子综合地影响了土壤侵蚀，且达到高度相关。研究区侵蚀强度较轻，但大于东北黑土区土壤容许流失量标准。农田是土壤水蚀的主要景观要素，同时也是水土保持的主战场。增加灌草地斑块、实施农田保护性耕作等将是该流域继续控制土壤侵蚀的有效办法之一。

Relationship between landscape pattern and soil erosion of an agricultural watershed in the Mollisols region of northeastern China

In recent years, there has been an increasing concern over soil erosion in the Mollisols region of northeastern China, which is one of the six water erosion regions in China. This region has become one of the most hazardous regions for potential erosion and desertification for unique physical geographical environment and drastic human activities. There is a close relationship between land use structure and soil loss. Land use changes can increase or reduce surface runoff and soil erosion. The relationship between landscape pattern and soil erosion has been rarely studied.A total of 30 sub-watersheds were chosen from Shuangyang river basin that is located at the eroded Mollisols region of northeastern China for examining their landscape metrics and soil erosion modulus. Correlation between landscape metrics and erosion modulus was analyzed using SPSS11.5 software. The objective of this study was to provide scientific basis for further erosion controlling and landscape planning in this region. The remotely sensed image (ETM+, August 30, 2002) of the area was classified into landscape map. We calculated landscape metrics with FRAGSTATS3.3 and soil erosion modulus with Revised Universal Soil Loss Equation (RUSLE) for 30 sub-watersheds.The results showed that the average soil erosion modulus was 6.58 in Shuangyang river basin. Erosion intensity is at low-grade according to the Standards for Gradation of Soil Erosion Intensity in China. But it is higher than that of soil loss tolerance in the Mollisols region, northeastern China. Correlation analysis showed a significant positive correlation between Percentage of Landscape (PLAND) of sloping tillage farmlands and soil erosion modulus; Contagion Index (CONTAG) was also positively related with soil erosion modulus. Significant negative correlation was found between erosion modulus and PLAND of shrub and grassland, as well as Simpson's Diversity Index (SHDI). Multiple correlation coefficients between the 9 landscape metrics selected in this study and erosion modulus was 0.931, which was higher than single-factor coefficients between any landscape metrics and erosion modulus. There was a linear regression relationship between the 9 landscape metrics and erosion modulus.Farmlands are main landscape types under erosion in the study area, where more soil and water conservation measures should be taken. It is necessary for soil loss control to increase forest and grassland patches and extend conservation tillage in farmlands.