Abstract: A better understanding of the spatial distribution of soil organic matter (SOM) plays a key role in further studying cycling process of elements in estuary wetland soil. We examined the spatial distribution of SOM at different soil layers in Minjiang estuarine wetland by using variogram, multifractal and spatial autocorrelation analysis. The results showed that the coefficient of variation for SOM in the layers of 0-20, 20-40 and 40-60 cm were generally similar and moderate, with values of 46.25%, 49.01%, and 50.49%. All the ratios of nugget to sill were less than 25%, suggesting that structural factors played a dominant role in spatial heterogeneity. With the increases of soil depth, the spatial fractal structures of SOM in different soil layers were different. The SOM content in 0-20 cm layer was the most uneven, suggesting a higher fractal degree and a larger spatial variability. The Moran’s I of SOM in all the three soil layers was more than 1.96, showing a significant positive spatial autocorrelation. The value of Moran’s I in layer 20-40 cm was the largest, showing a more significant spatial autocorrelation and a higher spatial aggregation degree than the other two layers. In brief, our results reveal horizontal distribution characteristics of SOM in estuarine wetlands and provide methodological support for researches on the SOM spatial distribution in similar regions.

Key words: bio-organic fertilizer, enzyme activity, microbial community functional diversity.