不同经营年限山核桃林地枯落物和土壤的水文效应

为探讨山核桃(Carya cathayensis Sarg.)—常绿阔叶混交林转变为山核桃纯林过程中林地枯落物和土壤水文效应的变化,利用相邻样地比较采样法,研究了山核桃—阔叶混交林0,5,10,20a山核桃纯林的水源涵养能力差异。结果表明,林地枯落物层持水量、吸水速率与浸水时间的关系分别符合对数函数和指数函数;0a林地的枯落物层蓄积量、最大持水量和有效拦蓄量显著高于5,10,20a的山核桃林地;随着经营年限的延长,林地枯落物层蓄积量、最大持水量和有效拦蓄量呈下降的趋势,与0a相比,分别下降了38.2%~54.6%,58.1%~69.7%,21.0%~33.2%;土壤容重、非毛管孔隙度、毛管孔隙度和总毛管孔隙度及持水力等指标在不同经营年限山核桃林地之间的差异并不显著,与0a土壤的持水力(21 450.0t/hm2)相比,经过不同年限的经营,持水力分别下降了10.6%~20.4%。总体上,山核桃—常绿阔叶混交林转变为山核桃纯林后,降低了林地枯落物和土壤的水文效应。

Hydrological Effects of Litters and Soils in Carya Cathayensis Forest with Different Managing Time

In order to investigate the effect of changes of forest type converted from chinese hickory(Carya cathayensis Sarg.)-evergreen broad-leaved mixed forest to pure C. cathayensis forest on litter and soil hydrological characteristics, we studied the difference of the water conservation abilities between C. cathayensis broad-leaved mixed forest and pure C. cathayensis forest in 0, 5, 10 and 20 a by using comparative sampling adjacent plots method. Results showed that woodland litter water-holding capacity, absorption rate and soaking time relations were in line logarithmic and exponential functions. The 0 a woodland litter accumulation, maximum water-holding capacity and effective interception amount were significantly higher than 5,10, 20 a C. cathayensis woodlands. As the extension of managing time, the woodland litter accumulation, maximum water-holding capacity and effective interception amount showed a downward trend. Compared with 0 a woodland, others decreased by 38.2%~54.6%, 58.1%~69.7% and 21.0%~33.2%. The differences of the soil bulk density, non-capillary porosity, capillary porosity, total capillary porosity and water holding capacity and other indicators in different managing histories of C. cathayensis forest were not significant. Compared with the water-holding capacity (21 450.0 t/hm²) of 0 a woodland soil, through different years of management, the water-holding capacity decreased from 10.6% to 20.4%. All of these indicate that the forest litter and soil hydrological effects were reduced after the C. cathayensis evergreen broad-leaved mixed forest was converted to pure C. cathayensis forest.