荒漠藓类结皮边缘效应下土壤肥力的灰色关联度分析

干旱半干旱地区土壤资源呈现高度异质性,植被分布斑块化成为该生态系统的普遍现象。藓类结皮是荒漠地表生物土壤结皮的主要类型,自然状态下藓类结皮通常呈现出典型的斑块状分布特征。应用灰色系统理论,以新疆北部古尔班通古特沙漠藓类结皮层土壤为研究对象,将藓类结皮斑块从中心至边缘划分3个圈层,通过对土壤的理化性质、酶活性、微生物生物量及微生物群落碳源利用等16项指标进行分析,利用灰色关联度分析法定量分析了藓类结皮斑块3个圈层的土壤肥力,并进行综合排序。结果表明:(1)藓类结皮斑块边缘圈层的土壤有机质、全氮、全钾、脲酶、过氧化氢酶、微生物生物量碳氮、平均吸光值(AWCD)均显著低于内部两个圈层,全磷、速效氮、速效磷、速效钾含量及pH值、碱性磷酸酶、蔗糖酶、β-葡萄糖苷酶活性均不受边缘效应的影响,在3个圈层无显著差异。同时,土壤各项指标在斑块内部两个圈层均无显著差异。(2)藓类结皮斑块3个圈层土壤肥力的关联度值依次为中心圈层(0.65)>中间圈层(0.59)>边缘圈层(0.47),藓类结皮斑块结皮层的土壤肥力从中心至边缘逐渐降低。藓类结皮斑块状分布显著影响土壤肥力,导致土壤肥力空间异质性程度增大,从而可能影响荒漠植物群落,尤其是草本植物群落的空间分布格局。

Grey Relation Analysis on Soil Fertility as Influenced by Edge Effects of Moss Crust Patch in a Temperate Desert

Patchiness is regarded as a common phenomenon of arid and semi-arid region due to highly heterogeneity. Moss crust, one of the main types of biological soil crusts in desert ecosystems, mainly occurred in the form of patches with different sizes. In order to determine the soil fertility of moss crust patch under the edge effect in Gurbantonggut Desert, soil physical and chemical properties, microbial properties and enzymatic activities were chosen as assessment indicators. Soil samples were collected from three cycles of moss crust patches, center, middle and edge cycles respectively. The data of soil fertility was analyzed quantitatively by grey relational analysis,and ranked by correlation degrees comprehensively. The results showed that: (1) SOM, TN, TK, UE, CAT, SMBC, SMBN and AWCD were significantly influenced by the edge effect, with higher contents in center and middle circle and less in the edge. However, there were no significant difference with the contents of TP, AN, AP, AK, pH, ALP, SC, β-GC among there circles. At the same time, all the soil properties showed no significant difference in the center and the middle circle. (2) The order of soil fertility in three circle with moss crust patch under the edge effect was center circle (0.65) > middle circle (0.59) > edge circle (0.47). We conclude that the soil fertility of moss crust patches present a trend of decrease from the center to edge. It was also proved that the existence of edge effects of moss crust patches could significantly influence soil fertility, which could consequently influence the spatial distribution pattern of vascular plant community, especially for those herbaceous communities.