陕西不同区域苹果林土壤水分动态和水分生产力模拟

基于WinEPIC和偏最小二乘回归模型对1981—2016年陕西不同区域成龄苹果林的水分生产力影响因子和土壤水分动态进行比较.结果表明: 研究期间,陕北丘陵沟壑区、渭北残塬区和关中平原区成龄苹果林年均产量分别为16.94、22.62和25.70 t·hm^-2,年均蒸散量分别为511.2、614.9和889.88 mm,水分生产力分别为3.81、3.82和3.24 kg·m^-3.在陕北区和渭北区,林地水分胁迫最严重,年均胁迫天数分别为54.89、28.38 d,关中区的N素胁迫较为剧烈,年均胁迫天数为25.87 d.陕北区和渭北区影响苹果林产量的最大因子是降水量,其标准化回归系数分别为0.274和0.235,但施N量对产量也有较大影响,回归系数分别达0.224和0.232;关中区的最大影响因子为施N量,回归系数为0.335,其次是供水量和施P量,回归系数分别为0.154和0.147.陕北区和渭北区影响苹果林水分生产力的最大因子是降水量,其标准化回归系数分别0.238和0.194;关中区最主要的影响因子为施N量和供水量,回归系数分别为0.182和0.178.在模拟期间,陕北区、渭北区和关中区苹果林地的过耗水总量分别为1152.17、1342.95和1372.42 mm,2~15 m土层土壤有效含水量下降速率分别为63.44、57.08、51.41 mm·a^-1,深层土壤干层出现时间分别为8、13和17年后,干层稳定至11 m深的时间分别为18、21和26年,干燥化严重.不同区域苹果林的管理重心应参考水分生产力的主导因子确定.

Simulation of soil water dynamics and water productivity of apple trees in different areas of Shaanxi Province,China.

Using WinEPIC and partial least squares regression model, we compared the driving factors of water productivity and soil moisture dynamics of several mature apple plantations in Shaanxi from 1981 to 2016. For the hilly and gully region of northern Shaanxi, the residual loess platform region in Weibei, and Guanzhong Plain, the average annual yield of mature apple forests was 16.94, 22.62 and 25.70 t·hm^-2, the annual average evapotranspiration was 511.2, 614.9 and 889.88 mm, and the water productivity was 3.81, 3.82 and 3.24 kg·m^-3, respectively. In northern Shaanxi and Weibei regions, water stress was the most serious, with the average annual stress days being 54.89 and 28.38 d, respectively. The N-level stress in Guanzhong region was severe, with an average annual stress day of 25.87 d. The largest factor affecting the yield of apple plantations in the northern Shaanxi and northern Weibei regions was the precipitation. The standardized regression coefficients were 0.274 and 0.235, respectively, the amount of N applied had a significant impact on the yield, with regression coefficients of 0.224 and 0.232, respectively. The maximum impact factor in Guanzhong region was the amount of N applied, with a regression coefficient of 0.335, followed by the amount of water supplied and the amount of applied P. The regression coefficients were 0.154 and 0.147, respectively. The dominant factor affecting the water productivity of apple plantations in northern Shaanxi and Weibei was precipitation, and the standardized regression coefficients were 0.238 and 0.194, respectively. The most important impact factors in Guanzhong region were the amount of N applied and the amount of water supplied, and the regression coefficients were 0.182 and 0.178, respectively. During the simulation period, the total water consumption of apple plantations in the northern Shaanxi, Weibei and Guanzhong regions was 1152.17, 1342.95 and 1372.42 mm, respectively. The effective water content decline rates of 2-15 m soil layers were 63.44, 57.08 and 51.41 mm·a^-1, respectively. The dry layer of deep soil appeared after 8, 13 and 17 years, and the dry layer was stable to 11 m deep for 18, 21 and 26 years, respectively, suggesting the drying status was severe. The management focus of apple plantations in different regions should be determined by the dominant factors of water productivity.