植被恢复影响土壤有机碳(SOC)空间分布.为阐明黄土丘陵沟壑小流域SOC的空间变异特征及其影响因素,以晋西蔡家川流域内的4个典型子流域(南北窑农地流域、北坡人工林流域、柳沟封禁流域、人祖山天然次生林流域)为研究对象,通过野外调查与室内测定SOC含量,采用经典统计学和地统计学方法,分析流域尺度0～100 cm SOC的分布规律及其与环境因子的关系.结果表明:不同子流域SOC含量不同,柳沟封禁流域＞天然次生林流域＞北坡人工林流域＞南北窑农地流域;相对于人工恢复,自然恢复能累积和储存更多的SOC;空间上,SOC呈自西向东逐渐降低的趋势,随深度增加,SOC的分布格局更具均一性;植被类型、土地利用方式、地形特征等因素影响小流域尺度SOC空间分布格局;灌草地SOC含量最高(14.43±8.91 g·kg-1),其次是林地(13.11±6.98g·kg-1),农地SOC含量最低(8.48±2.98g·kg-1);较之农地,灌草地和林地SOC含量分别提高70.2％和54.6％;在0～20 cm 土层,坡度为15°～25°时SOC含量出现最大值;在0～20 cm土层,不同坡向对SOC含量大小排序为阴坡(15.82±7.63 g·kg-1)＞半阴坡(12.94±7.53 g·kg-1)＞半阳坡(11.48±6.28g·kg-1)＞阳坡(11.1±6.19g·kg-1).研究结果为评价黄土流域植被恢复的土壤生态效应提供依据.在植被恢复和重建过程中,要注意人工林天然化、对应的天然林进行封禁管理.
Spatial distribution and influencing factors of soil organic carbon in loess small watershed in western Shanxi Province
Vegetation restoration affects the spatial distribution of soil organic carbon(SOC).We examined spatial variations and influencing factors of SOC in small watershed of loess hills and gullies,across four typical sub-water-sheds(Nanbeiyao agricultural land watershed,Beipo artificial forest watershed,Liugou enclosed watershed,and Renzushan natural secondary forest watershed)in Caijiachuan watershed in western Shanxi Province.Through field investigation and indoor analysis,we analyzed the distribution of SOC and its relationship with environmental factors in 0-100 cm profile of watershed scale using classical statistics and geostatistics methods.SOC content varied in dif-ferent sub-watersheds,with Liugou enclosed watershed＞Renzushan natural secondary forest watershed＞Beipo artificial forest watershed＞Nanbeiyao agricultural land watershed.Compared with artificial restoration,natural res-toration accumulated and stored more soil organic carbon.Spatially,SOC decreased gradually from west to east.The distribution pattern of SOC was more uniform with increasing soil depth.Vegetation type,land use pattern,and top-ographic characteristics affected the spatial distribution pattern of SOC at the small watershed scale.The SOC con-tent of shrub-grassland was the highest(14.43±8.91 g·kg-1),followed by forest land(13.11±6.98 g·kg-1),and the agricultural land(8.48±2.98 g·kg1).Compared with agricultural land,the content of SOC in shrub-grassland and forest land was increased by 70.2％and 54.6％,respectively.In 0-20 cm soil layer,the maximum value of SOC occurred when the slope was 15°-25°.In 0-20 cm soil layer,SOC content in different slope direc-tions was in order of shady slope(15.82±7.63 g·kg-1)＞half shady slope(12.94±7.53 g·kg-1)＞half sunny slope(11.48±6.28 g·kg-1)＞sunny slope(11.1±6.19 g·kg-1).The results provide a basis for evaluating soil ecological effects of vegetation restoration in the loess watersheds.Attention should be paid to nature-approaching management of artificial forests and enclosed management of natural forests during vegetation restoration and recon-struction.
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