Objective  To study the spatial distribution of soil organic matter in Mayi lake, the water source of the eastern ecological barrier of Karamay city, and provide scientific basis and data support for the ecological environment protection of the lake area.

Method  The study area of this paper was Mayi lake. Through field sampling and indoor analysis, the study used trend analysis method, inverse distance weight interpolation method, spatial autocorrelation method and semi-variogram function method to analyze the spatial distribution law of soil organic matter at different depths of Mayi lake.

Result  The trend analysis showed that the change rates of soil organic matter content in Mayi lake were different from 0−20, 20−40, 40−60 and 60−80 cm soil layers, but the overall trend was that soil organic matter content increased in the north-south direction and decreased in the east-west direction. The inverse distance weight interpolation method (IDW) showed that there are large horizontal distribution differences of soil organic matter contents in different soil layers, and regional obvious vertical distribution characteristics of soil organic matter content in Mayi lake. The trends in soil organic matter content change were highly consistent with trend analysis method. The overall performance of the north-south direction of soil organic matter content increased, the east-west direction showed a trend of decrease. The spatial autocorrelation method showed that Moran indexes of four layers were 0.164 3, 0.123 6, 0.195 5 and 0.246 1 respectively, showing a significant positive correlation on the space. The Z values of 0−20, 20−40, 40−60 and 60−80 cm soil layers were 3.151 0, 2.593 4, 3.590 3 and 4.635 5 respectively. The soil organic matter of underlayers (40−60, 60−80 cm) had obvious positive spatial correlation with the highest space aggregation degree. The surface layers (0−20, 20−40 cm) had no significant spatial correlation, and low spatial aggregation degree. The semi-variogram function method showed that the nugget effects of the underlayers (40−60 and 60−80 cm) were 0.427 and 0.420 respectively, indicating spatial correlation of soil organic matter was general. The nugget effects of the surface layers (0−20 and 20−40 cm) were 0.033 and 0.045 respectively, indicating high spatial correlation of soil organic matter.

Conclusion  The contents of soil organic matter in different soil layers vary greatly, and the north-south direction tends to increase, while the east-west direction tends to decrease. The spatial correlations of soil organic matter in the surface layers (0−20 and 20−40 cm) are not significant, and the spatial aggregation degrees are low, while the spatial correlations are significant and the spatial aggregation degrees are high in the underlayers (40−60 and 60−80 cm). The spatial heterogeneity of soil organic matter content is greatly affected by soil type, soil texture, vegetation type and the variation of lake area. While constructing ecological barrier in the periphery of lake area, the selection of shelterbelt tree species, planting depth and planting density should be combined with the spatial distribution of soil organic matter content.