Distribution Characteristics of Soil Organic Matter and Total Nitrogen on the Yajiageng Vertical Belt,Gongga Mountain around the Dadu River Banks

Distribution characteristics of soil organic matter(SOM) and total nitrogen(TN) were studied in different plant communities of the Yajiageng vertical belt in Gongga Mountain around the Dadu River banks. The results show:① the contents of SOM and TN of the plant communities gradually decreased with the follow-ing order:subalpine coniferous forest (3 027 m), subalpine meadow (3 873 m), coniferous broadleaved mixed forest(2 737 m), subalpine shrub(3 565 m) and treeline(3 564 m). ② With soil profile depth increasing, the contents of SOM and TN gradually de-creased. For different vegetation types, the contents of SOM and TN in sub-alpine coniferous forest were higher than that of other vegetational types. ③The ratio of the content of carbon to the content of total nitrogen (CC/CTN )was 13.5-27.6, which was relatively lower than the appropriate CC/CTN of 25-30, and indicated that the soil in favor of the organic matter decomposed and nutrients released. CC/CTN in the soil had no correlation with sea level altitude. However,its distribution in the soil varied with different vegetation types. ④ Nitrogen in SOM existed mainly in the form of organic nitrogen, and CC/CTN in the soil was not obvious correlated with SOM and TN.