新疆艾比湖流域土壤有机质的空间分布特征及其影响因素

根据新疆艾比湖流域土壤有机质(SOM)数据,分析了土壤质地、植被群落类型和土壤剖面深度3个因素对SOM含量的影响,进一步研究了流域内有机质在不同土壤深度的空间分布特征及其沿土壤剖面深度垂直分布的空间异质性。结果表明:植被群落类型显著影响SOM含量,而土壤质地和深度对有机质总体分布水平影响不显著;随土壤深度变化有机质分布呈现不同的空间变异特征,流域内0—80 cm土壤有机质高含量区域与低含量区域斑块化分布呈现孔穴特征,但在80—120 cm土壤有机质含量变化较为连续,呈现流域东、西两端高而中间低的分布特征;有机质沿土壤深度垂直分布模式在流域内表现出分异特征,流域中部SOM随土壤深度增加而降低,SOM含量从0—20 cm浅层土壤的2.85 g/kg降至100—120 cm深层土壤的1.51 g/kg;但在流域东部和西部SOM随土壤深度增加呈升高趋势,流域西部SOM含量从0—20 cm土壤的1.80 g/kg大幅增加至100—120cm土壤的6.61 g/kg,流域东部SOM含量则从0—20 cm土壤的1.04 g/kg逐步增至100—120 cm土壤的2.86g/kg。艾比湖流域有机质在浅层和深层土壤不同的空间分布特征与干旱区绿洲生态景观斑块化分异特征和植被根际沉积特点密切相关,流域内土壤剖面成土演化的空间异质性对有机质沿土壤深度垂直分布的空间变异性有显著制约。

The characteristics of the spatial distribution of soil organic matter and factors influencing it in Ebinur Lake Basin of Xinjiang Autonomous Region, China

Based on soil organic matter (SOM) data from the Ebinur Lake Basin in the Xinjiang Uygur Autonomous Region of western China and three-way ANOVA we analyzed whether SOM content was significantly influenced by three factors: the soil type, the vegetation type and the soil depth. A semi-variogram and Ordinary Kriging (OK) models were then used to study the spatial variability of the SOM at different soil depths. Finally, the vertical spatial variations of the SOM were investigated using the empirical orthogonal function (EOF) decomposition. Ebinur Lake is a rift lake in northwest China near the border with Kazakhstan. Vegetation types vary from low hygrophyte salt-tolerant shrubs to tall drought-tolerant Populus euphratica forests and grow on clay, loam, and sand soils.The results of ANOVA show the vegetation type significantly affects the SOM content, but the soil type and soil depth have not influenced SOM content in a statistically significant manner. The results of the semi-variogram and Ordinary Kriging analysis show spatial variability of SOM content exhibits different characteristics with changes in soil depth; also the high- and low-SOM content regions display a patchy pattern in the 0-80cm soil layer in the Ebinur Lake Basin. However, the SOM content changes are relatively continuous in the 80-120cm soil layer, and the SOM content is higher in the eastern and western parts of the region than in the central region of the Ebinur Lake Basin. The spatial variation patterns satisfy the hole model in the 0-80cm soil layer, while the exponent model is fitted well in the 80-120cm soil layer in the semi-variogram. Also, the results of the EOF analysis illustrate the vertical spatial distribution of SOM shows different characteristics with the soil depth across the Ebinur Lake Basin. Specifically, the SOM content decreases as the soil depth increases in the central part of the Basin. In that area, SOM content drops gradually from 2.85g/kg in the 0-20cm soil layer to 1.51g/kg in the 100-120cm soil layer. However, the SOM content displays an increasing trend with increasing soil depth in the eastern and western regions of the Ebinur Lake Basin. Specifically, the SOM content increased substantially from 1.80g/kg in the 0-20cm soil layer to as much as 6.61g/kg in the 100-120cm soil layer in the western region, and the SOM content increased gradually from 1.04g/kg in the 0-20cm soil layer to 2.86g/kg in the 100-120cm soil layer in the eastern region of the Basin.In the Ebinur Lake Basin, the patterns of spatial variation in the SOM are extremely significantly different between the shallow soil layers when compared to the deeper soil layers, and this characteristic is strongly relevant to the patches of the arid oasis ecological landscape and the features of the vegetation rhizodeposition. Also, the spatial heterogeneity during evolution of the soil profiles in the Basin suggests a significant restraining effect on vertical spatial variability of the SOM with soil depth. Our results provide a scientific basis for rational land use, vegetation protection and the ecological restoration policy-making process in the Ebinur Lake Basin.