荒漠草原区不同年限柠条林表层土壤碳分布及影响因素

Carbon Distribution in Surface Soil and Its Impact Factors During Caragana intermedia Shrubland Development in Desert Steppe

沙化草地种植人工林可以固定截存大气中的C而增加土壤C含量和储量,但在荒漠草原区固沙柠条(Caragana intermedia)林发育过程中表层土壤C分布规律及影响因素,尚不清楚。通过调查6a,15a,24a,36a固沙柠条林下、林间表层土壤C含量和储量分布特征,结合土壤机械组成和地表植被特征调查,分析了柠条林发育过程中表层土壤C分布规律及其与环境因素之间的关系。结果表明:(1)随着柠条林生长,林下表层土壤C含量和储量以及C/N均与林龄呈现单调线性回归关系(P<0.05)。从6a到36a的林地,林下表层土壤C含量和储量呈现单调递增趋势,而土壤C/N呈单调递减。24a生林地林下表层土壤C含量和储量开始显著高于林间(P<0.01)。(2)随着林龄增加,林间表层土壤C分布变化未达到显著水平(P>0.05)。但是柠条林发育生长对林间具有一定辐射作用,从24a到36a的林地,林间表层土壤C含量和储量开始明显增加,林间和林下表层土壤C分布差异性逐渐降低。(3)林下小尺度表层土壤C分布决定了整个林地表层土壤C分布。随着林龄增加,林地表层土壤有机碳含量和储量逐渐增加;同时表层土壤全氮的快速积累,导致土壤C/N无显著变化。(4)在荒漠草原区,柠条林发育在增加林下表层土壤C分布的同时,对林间表层土壤C分布具有一定的辐射效应。在柠条林生长过程中,该林地表层土壤C含量和储量呈现增加趋势。

The artificial shrub planted in sandy grassland can intercept the air carbon and facilitate the soil car- bon content and storage. However, the carbon distribution in surface soil and related impact factors during shrubland （C. interrnedia） development in desert steppe were largely unknown. An investigation on surface soil carbon content and storage under the shrub and in the open was carried out in lands grown shrubs with the shrub ages of 6, 15, 24 and 36 years. By analyzing soil particle-size distribution and ground herbaceous vegetation, the surface soil carbon distribution and its relation to environmental variables were discussed. The results were as follows： （1） there was a linear regression between surface soil carbon content and storage and C/N under the shrub and stand age （P〈0.05）, with significantly increased surface soil carbon content and storage and decreased soil C/N; （2） there was a spreading effect of stand development on surface carbon distribution in the open between shrubs, where surface soil carbon content and storage increased from 24 to 36 years of shrubland though with no significance （P^0.05） ; （3） the surface soil carbon distribution at small scale under shrub determined the surface carbon distribution of whole stand, and surface soil carbon content and storage were enhanced for the whole stand at big scale during stand development. With the accu- mulation of soil nitrogen, there were no significant differences of soil C/N between these four shrublands;（4） the stand development could not only facilitate surface soil carbon distribution under the shrub in desert steppe, but also have a spreading effect on surface carbon distribution in the open. This was beneficial for the enhancement of surface soil carbon content and storage of grassland ecosystems during the recovery process.