晋西黄土区刺槐和油松林地土壤水分动态变化

以晋西黄土区蔡家川流域不同坡向的刺槐和油松林地为研究对象,在2005-2012年对刺槐和油松固定样地0 ～ 200 cm土层的土壤水分进行定位观测,采用有序样本最优分割法分析刺槐和油松林地土壤水分年内、年际变化规律,探讨降雨分配情况对年内、年际刺槐和油松林地土壤水分变化的影响.结果表明：1）研究区刺槐和油松林地土壤水分年内变化可分为平稳期、波动期、积累期和消退期4个时段,阳坡刺槐林地和油松林地土壤水分条件接近,阴坡刺槐林地土壤水分条件最好;2）在偏早年,油松林地土壤水分亏缺量比刺槐林地小,当偏旱年与正常年相间时,油松林地土壤水分恢复速度比刺槐林地快;3）年内降水分配均匀度与刺槐和油松林地土壤水分年内波动幅度成反比,刺槐和油松林地土壤含水量年际变化滞后于降雨的年际变化.建议在晋西黄土区阳坡种植油松,阴坡种植刺槐.

Dynamic changes of soil moisture in Robinia pseudoacacia and Pinus tabuliformis forestlands in loess region of western Shanxi Province

The study was conducted on Robinia pseudoacacia and Pinus tabuliformis forestlands of different slope aspects in Caijiachuan watershed,a loess region of western Shanxi Province.Based on the located observation of soil moisture at 0-200 cm soil layer of fixed sample plots in R.pseudoacacia and P.tabuliformis forestlands from 2005 to 2012,optimal partition for ordinal specimen method was used to analyze the annual and interannual changes of soil moisture in R.pseudoacacia and P.tabuliformis forestlands,and the influence of precipitation distribution on annual and interannual changes of soil moisture in R.pseudoacacia and P.tabuliformis forestlands was discussed.The results showed that：1） the annual dynamics of soil moisture in R.pseudoacacia and P.tabuliformis forestlands in the study area could be divided into four stages：stable stage,fluctuating stage,accumulative stage and consumption stage ; in sunny slopes,the soil moisture condition of R.pseudoacacia forestland was similar to that of P.tabuliformis forestland,while in shady slopes the soil moisture condition of R.pseudoacacia forestland was the best; 2） the soil moisture deficit amount of P.tabuliformis forestland was less than that of R.pseudoacacia forestland in drought years,and during the interphase period of drought years and normal years,the soil moisture of P.tabuliformis forestland recovered faster than R.pseudoacacia forestland ; 3） the annual precipitation distribution evenness was inversely proportional to the annual fluctuation range of soil moisture in R.pseudoacacia and P.tabuliformis forestlands,while the interannual change of soil moisture content in R.pseudoacacia and P.tabuliformis forestlands lagged behind the interannual change of precipitation.The suggestion of planting P.tabuliformis in sunny slopes and R.pseudoacacia in shady slopes was proposed for the vegetation rehabilitation in the loess region of western Shanxi Province.