六盘山主要森林类型枯落物的水文功能

Hydrological functions of litter layer of typical forest types in the Liupan Mountains of Ningxia,northwestern China

为了定量评价森林枯落物的水文功能,该文通过浸水法和野外观测,调查了宁夏六盘山主要森林类型的枯落物蓄积量,研究了持水能力与过程,并对辽东栎与少脉椴混交林分的枯落物进行了截留及蒸发研究。结果表明：六盘山主要森林类型的枯落物蓄积量达4.87-30.86 t/hm^2,其中针叶林〉阔叶林〉灌丛;各植被类型的最大持水率相差较大,一般介于177.68%-387.42%,不同植被类型枯落物层的最大持水量为0.9-7.6 mm,最大拦蓄量为0.36-4.96 mm,有效拦蓄量为0.23-3.82 mm,均表现为针叶林〉阔叶林〉灌丛。浸水实验表明：枯落物的持水量随浸泡时间的增加呈对数曲线增长,吸水速率与浸泡时间呈反函数关系。2005年6月19日—7月26日,辽东栎与少脉椴混交林枯落物层的截留量占同期降水的比率为1.98%,平均日蒸发速率为（0.12±0.058）mm,占林分总蒸散量的8.28%;枯落物层的蒸发速率随含水率增加呈S形曲线增长。

Hydrological functions of forest litter layer in the eight main forest types （ Quercus liaotungensis, Pinus armandii, Pinus tabulaeformis, Betula albo-sinensis, Betula platyphylla, Populus davidiana, mixed forest of Q. liaotungensis and Tilla paucicostata, and shrub ） in the Liupan Mountains of Ningxia, northwestern China, were investigated by measuring litter biomass and its water-holding capacity using the soaking-and- weighing method. In addition, the interception and evaporation rates of litter were measured in a mixed stand of Q. liaotungensis and T. paucicostata during June 19-July 26, 2005. It was found that the litter biomass of main forest types ranged from 4.87 to 30.86 t/hm2 , with a rank of conifer forest 〉 broadleaved forest 〉 shrubs. The weight-based ratio of water-holding capacity varied significantly among the main forest types, ranging from 177.68% to 387.42%. The water-holding capacity of litter layer in different forest types varied from 0.9 to 7.6 mm, and the maximum interception rate ranged from 0.36 to 4.96 mm. The effective interception rate ranged from 0.23 to 3.82 mm, and all these parameters followed the order of conifer forest 〉 broadleaved forest 〉 shrubs. The litter soaking experiments showed that the water-holding amount increased with soaking time, following a logarithmic curve, while the absorption rate decreased with time. The ratio of interception to the precipitation in the study period from June＇ 19 to July 26, 2005 was 1.98% for the mixed stand of Q. liaotungensis and T. paucicostata. The mean daily evaporation rate was（0.12 ＋ 0.058） mm, accounting for 8.28 % of the total evaporation of this stand. The evaporation rate of litter increased with rising litter moisture, following a S-shape curve.