Soil Aggregate Stability And Nutrient Distribution Characteristics Of Larix Principis-rupprechtii Plantations In Taiyue Mountain Of Shanxi Province

Larix principis-rupprechtii is an important plantation forest resource in China,which plays an important role in wind and sand fixation and carbon sequestration.In this study,the Larix principis-rupprechtii plantations with different densities and forest ages in Taiyue Mountain,Shanxi Province were studied.Four different density stands were selected,and the thinning intensities were 0%,15%,35%,and 50%,respectively.The pure Larix principis-rupprechtii forests of 30a,40a,and 50a and the mixed forests of Larix principis-rupprechtii with 15a,26a,and 40a were selected.By exploring the proportion of soil aggregates in different forests,the stability of soil aggregates and the differentiation of organic carbon,total nitrogen and total phosphorus in agglomerates were explained.The correlation between the aggregates in the soil and the nutrient contents in the aggregates was explained.The results show:The proportion of soil aggregates in Larix principis-rupprechtii plantation in the study area is as follows:the proportion of soil macro-aggregates is higher than that of micro-aggregates,and the soil aggregates of>2mm and 2-0.25mm account for more than 78%of the total aggregates.Stand density and stand age can affect the stability of soil aggregates.With the change of stand density,soil parameters MWD and GMD were highest under mild density control and lowest under severe density control.In the pure Larix principis-rupprechtii forest,the stability of soil aggregates increases with the age of the stand.In the mixed forest of Larix principis-rupprechtii,the soil MWD and GMD values were ranked as 26a>40a>15a.The soil layer gradually deepened from 0-20cm,and the organic carbon and total nitrogen content of the soil aggregates decreased gradually.Stand density can affect the nutrient content in soil aggregates.Under moderate regulation,the content of organic carbon,total nitrogen and total phosphorus in soil aggregates is the largest.As the density of the stand decreased,the nutrient content showed a trend of increasing first and then decreasing.The change in stand density has a significant effect on the nutrient content in the 0-20 cm soil layer.In the pure Larix principis-rupprechtii forest,the organic carbon and total nitrogen in the soil aggregates decreased first and then increased with the increase of forest age,and the content was highest in 50a.In the mixed forest of Larix principis-rupprechtii,organic carbon was the most abundant in>2mm soil aggregates,and total nitrogen and total phosphorus were mainly distributed in 0.25-0.053mm soil aggregates.The forest age has a significant effect on the nutrient distribution both in the soil aggregates in pure and mixed forests.