异质景观条件下江汉平原土壤的空间分异

景观异质与土壤分异息息相关。以DEM数据为基础,以海拔50m、100m为界,将江汉平原划分为平原湖区景观、平缓岗地景观及起伏丘陵景观3种类型。在ArcG IS 10支持下,将江汉平原土壤图与景观类型图进行叠置分析,提取不同景观类型片区各土壤亚类斑块周长、面积等信息,计算了各景观类型片区各土壤亚类的分维数、平均斑块面积、稳定度等信息,定量分析了江汉平原各景观类型片区土壤空间分异特征,结论如下:(1)不同景观类型区各土壤亚类分布差异明显,起伏丘陵景观区主要以红壤和黄棕壤地带性土壤为主;平原湖区潮土和水稻土等耕作土非常发育;平缓岗地区地带性土壤和耕作土壤平分秋色。(2)连片性较好的土壤亚类呈现不同的景观选择性:耕作土集中分布于平原湖区景观片区;地带性土壤多集中分布于丘陵和岗地景观片区。(3)平原湖区面积很大,各类土壤都有发育的空间,土壤亚类之间分维数和稳定度差别比较大;平缓岗地景观区由于面积非常局限,土壤亚类发生发育受到空间的限制,边界破碎化,分维数平均都比较大,斑块镶嵌结构均比较复杂,稳定度差别较小。(4)主要土壤亚类的分维数和稳定性指数值一定程度地反映了各主要土壤亚类的最匹配的景观类型,即能够提供其发生发育的最佳条件。研究有利于深入认识土壤形成和演化规律,为土壤资源的合理利用及定向培育服务。

The spatial differentiation of soil in heterogeneous landscapes of the Jianghan Plain

Landscape heterogeneity is closely related to soil differentiation. The Jianghan Plain is divided into three landscape types:Plain Lake, Gently Gradated Mounds, and Rolling Hills, delineated according to contour lines of 50 m and 100 m, based on DEM data. The overlay analysis of the soil and landscape type maps was done to extract data describing the soil subgroup patches, as well as their perimeters and areas, etc. in different landscape types. This analysis was supported by the ArcGIS10 platform. Then, some indices, such as the fractal dimension, average patch area, and stability index were calculated to quantitatively analyze the spatial differentiation of the soil in different landscape types. The results are as follows:(1) There is significant spatial differentiation of soil subgroups in different landscape types. The Rolling Hills landscape is mainly composed of zonal soils, including red soil and yellow brown soil. Arable soil types such as fluvo-aquic and paddy soil are very well developed in the Plain Lake landscape, while zonal and arable soils are equally represented in the Gently Gradated Mounds landscape. (2) Every subgroup soil with good connectivity exhibited a landscape selectivity bias. Arable soils with good connectivity appear to be mostly concentrated in the Plain Lake landscape, while the most concentrated zonal soils are found in the Gently Gradated Mounds and Rolling Hills landscapes. (3) The Plain Lake landscape on the Jianghan Plain is large enough that all soil subgroups were found to be well developed in that area. Thus, the differences among the fractal dimension (D values) or the stability index values of the different soil subgroups are larger, which can better reflect soil intrinsic characteristics. However, in the Gently Gradated Mounds landscape, soil development and evolution is restricted by space, so the boundaries of the soil subgroups are fragmented and the associated fractal dimension values (D values) are larger on average. The larger fractal dimension values (D values) reflect the more complex mosaic structures of the soil subgroup patches in that landscape. However, because the D values are universally larger in the Gently Gradated Mounds landscape, the differences among the fractal dimension values of the different soil subgroup patches are smaller, as are the stability index values of the soil subgroup patches. (4) The value of the fractal dimension, or the stability index of a soil subgroup, reveals the best-matched landscape type to some degree, which in turn provides the ideal conditions for the soil subgroup to develop or evolve well. This research improves our understanding of the evolution of soil, and facilitates the rational use and the directed breeding of soil resources.