陕北黄土丘陵区土壤碳氮库对人工植被恢复的响应

Response of soil organic carbon and total nitrogen pool to different types of artificial vegetations in the gully region of Loess Plateau

为揭示陕北黄土丘陵区深层土壤碳氮含量及储量对不同人工植被恢复的响应特征,在典型退耕还林区,选择恢复30年的人工刺槐、柠条林地、撂荒地及坡耕地,分析0～200 cm土层有机碳和全氮剖面分布和数量的变化状况.结果表明：不同植被类型有机碳和全氮含量均在0～100 cm土层随土层加深呈下降趋势,而100～ 200 cm趋于平缓.较坡耕地,3种植被下100～200 cm深层土壤有机碳密度平均增加7.93 Mg/hm^2,全氮密度平均增加0.65 Mg/hm^2.且3种植被下100～200 cm深层土壤有机碳和氮密度平均分别占到0～200 cm深土壤的24.4％和26.7％,分别是坡耕地的1.52倍和1.85倍.因此,长期人工植被恢复下能够增加土壤深层（0～ 200 cm）有机碳和全氮储量,并且以刺槐林提升土壤碳氮储量潜力较高.

Aiming at revealing the response mechanism of soil organic carbon （SOC） and total nitrogen in deep soil under different artificial vegetations in hilly region of Loess Plateau,30 years recovery forest land （Robinia vegetation,Cragana vegetation）,abandoned land and slope farmland in the typically grainto-green program region were used to analyze the effect of distribution and quantity of organic carbon （SOC） and total nitrogen in 0-200 cm soil profile under different vegetations.The results demonstrated that the concentration of SOC and total nitrogen decreased with soil depth in 0-100 cm layer,and remained stable in 100-200 cm layer.Compared with slope farmland,three types of vegetations increased the density of SOC 7.93 Mg/hm^2 and total nitrogen 0.65 Mg/hm^2 on average in 100-200 cm soil layer.In addition,the average density of SOC and total nitrogen in 100-200 cm soil layer under 3 types of vegetations accounted for 24.4％ and 26.7％ respectively in 0-200 cm soil layer,which was 1.52 times and 1.85 times as that of slope farmland in the same soil layer.The artificial vegetation significantly increased soil organic carbon and nitrogen stocks in deep soil layers after long time recovery,and Robinia was better for carbon and nitrogen sequestration.