Soil Carbon and Nitrogen Sequestration Under Several Different Forest Lands Converted by Farmland in Loess Hilly Area
This research was conducted lo determine the change of soil organic carbon and nitrogen in 0-60 cm soil layers under four types forested lands: Caragana, robinia, Chinese pine and orientals, which has been converted by farmland for 10 years and 30 years in loess hilly area. The results showed that, compared with sloped farmland, either content or density of soil organic carbon and nitrogen in different soil layers were significantly increased in Chinese pine and onentalis forest land after 10 years forestation. Compared with 10 years forestation, the soil organic carbon and nitrogen was further increased after 30 years forestation, with the order of organic carbon: onentalis >Chinese pine>robinia>caragana, and that organic carbon sequestration rate(0~60 cm soil layers) reached 1.06, 0.71, 0.43, 0.36 mgC·hm-2·a-1, respectively. In contrast, the rate of nitrogen sequestration was the highest by 0.051 mgN ·hm-2·a-1 under planting robinia, and was nol significantly different among other forest lands by 0.014-0.026 mgN ·hm-2·a-1. After the 30 years forestation, the soil organic carbon increased mainly from 0-20 cm soil layer with average contribution ratio of 51.9% under all forest land, and the soil nitrogen increased mainly from 40~ 60 cm deep soil layer with average contribution ratio of 42.5% in all forest land except for robinia. The ratio of C/N also increased in 0~20 cm soil layer under different forest lands. There was significant regression correlation between soil organic carbon and nitrogen. In summary, conversion of cropland to forest could sequestrate carbon and nitrogen in soil, from which, buckthorn and robinia were a better to improve soil organic carbon pool and soil nitrogen pool, respectively.
conversion of cropland to forestsoil organic carbonsoil total nitrogenloess hilly area
国家科技期刊平台
NSTL
万方数据
维普
