Water Balance of Different Age Pinus tabulaeformis Forests in Taihang Mountain,Shanxi | 山西太行山不同林龄油松林的水量平衡

Chinese. 采用空间代替时间的方法,对太行山油松中龄林（22年生）和成熟林（58年生）水量平衡组分的季节性变化进行同步观测,探讨林龄对生态系统蒸散及水量平衡的影响。结果表明：油松中龄林、成熟林生长季总蒸散（包括蒸腾、蒸发和截留）量分别为406.87和418.49mm,水分总支出量分别为431.07和459.57mm,均无明显差异,但蒸散和支出组分不同,成熟林乔木层蒸腾量、乔木层截留量、枯落物截留量、地表径流量各自占降雨量（445.4mm）的比率比中龄林分别下降了6.01%,2.21%,0.81%和0.26%,而灌草群落蒸散量、土壤出流量和灌草层截留量各自占降雨量的比率比中龄林分别增加了8.80%,3.87%和2.94%。林龄变化主要改变了蒸散和水分支出各组分的贡献率,而不是其总量;成熟林生长季土壤含水量略有下降,而中龄林小幅增加。

English. The seasonal changes in water balance components were simultaneously measured in middle-aged（22 a）and mature（58 a） Pinus tabulaeformis forests in Taihang Mountain by using ＂space replacing time＂ method. The results indicated that the total evapotranspiration（406.87-418.49 mm） and total water output （431.07-459.57 mm）did not differ substantially between two forests. However, evapotranspiration and water output components varied with forest ages, Compared with these in the middle-aged forest, the proportion of arbor canopy transpiration, arbor canopy interception, litter interception and surface runoff to precipitation in the mature forest decreased by 6.01%,2.21%,0.81% ,and 0.26% , respectively, while the proportion of evapotranspiration and interception of the shrub and grass layers and the soil water outflow increased by 8.80%,3.87% ,and 2.94% , respectively. Variation in stand age might be the main factor affecting relative contribution of evapotranspiration and water output components without changing their total amount. In growing season, the soil water content in the mature forest decreased slightly, whereas it increased by small amplitude in middle-aged forest.