晋西北黄土丘陵区人工林地土壤水分亏缺评价

Assessment on Soil Water Deficit Under Different Artificial Forestland in Loess Hilly Regions of Northwestern Shanxi Province

[目的]定量评价半干旱黄土丘陵区人工林地土壤水分亏缺现象,为科学指导该区域合理配置植被和生态恢复建设提供理论依据。[方法]以地处晋西北的五寨县为目标研究区域,通过构建土壤水分亏缺定量评价模型,对柠条林(Caragana korshinskii)、小叶杨林(Populus simonii)、油松林(Pinus tabuliformis)土壤水分相对亏缺指数和样地土壤水分相对亏缺指数进行计算。[结果]3种人工林地均有不同程度的土壤水分相对亏缺现象,小叶杨林和柠条林在0—200cm有轻微土壤水分亏缺,小叶杨林在200—600cm深度内没有土壤水分亏缺,柠条林在200cm深度以下土壤水分亏缺值随土层深度增加而升高;油松林在0—200cm土层深度内,土壤水分亏缺严重,在200cm深度以下土壤水分亏缺值随土层深度增加而有所降低;3种林地的样地土壤水分相对亏缺指数分别为0.16,-0.12和0.31,油松林的土壤水分亏缺程度高于另外2种林地;3种人工林地均有不同程度的干层分布,以轻度和中度干层为主,油松林在浅层土壤有重度土壤干层发育。[结论]晋西北黄土丘陵区3种人工林地中,油松林土壤水分亏缺最为严重。

[Objective]We aimed to quantitatively assess the soil water deficit under vegetation in the semiarid loess hilly region in order to provide theoretical support for the selection of vegetation types and ecological restoration pattern.[Methods]The compared soil water deficit index（CSWDI）and plot compared soil water deficit index（PCSWDI）of Caragana korshinskii,Populus simonii Carr and Pinus tabulaeformis in soil profiles of 0—600cm deepth were calculated to quantify soil water deficit and its profile distribution under different vegetation types on April,May,June and July in Wuzhai County,Northwestern Shanxi Province.[Results]Soil water deficit appeared in all three artificial forestland.Soil water deficit was found in P.simonii and C.korshinskii in soil layers between 0and 200 cm,however,it was hardly found in P.simonii between 200 and 600cm.Below 200 cm,soil water deficit increased with increasing CSWDI in C.korshinskii.The P.tabulaeformis had led to a serious deep soil desiccation,especially in soil layers from 0to 200 cm.Soil water deficit decreased in the layers below 200 cm with the increase of soil depths in P.tabulaeformis.PCSWDI of C.korshinskii,P.simonii and P.tabulaeformis was 0.16,-0.12 and 0.31,respectively.The soil water deficit of P.tabulaeformis was more severe than that in the others two forestland.The dried soil layer was distributed in all three artificial forestland with a different degree,mainly for mild and moderate dry layer distribution.Extreme dry layer presented in shallow soil of P.tabulaeformis.[Conclusion]The soil water deficit in the P.tabulaeformis was the severest among the three artificial forests in the loess hilly regions.