内蒙古大兴安岭南段山杨纯林与白桦纯林的枯落物层水文效应

Hydrological Effects of the Humus Layer of Pure Forest of Populus davidiana and Betula platyphylla in Southern Section of Daxing’anling Mountains,Inner Mongolia,China

[目的]在暖干化气候变化导致干旱胁迫带来大量树木死亡的赛罕乌拉国家级自然保护区,选择典型林分,研究其枯落物层蓄积量和水文功能。[方法]选取山杨(Populus davidiana Dode)纯林与白桦(Betula platyphylla Suk.)纯林2种林分,各设立9块典型样地,测定枯落物现存量,并采用室内浸泡法测定其枯落物层持水能力,探究2种林分的枯落物层水文效应。[结果]研究表明:(1)在相同郁闭度条件下,山杨纯林的枯落物总储量为12.41 t·hm^(-2),稍高于白桦纯林的10.97 t·hm^(-2)。(2)山杨纯林、白桦纯林的枯落物层的最大持水量为26.85、26.77 t·hm^(-2),有效拦蓄量为11.96、11.07 t·hm^(-2),二者相近。(3)枯落物的动态持水量与浸水时间呈对数函数关系,吸水速率与浸水时间呈幂函数关系。[结论]内蒙古大兴安岭南段山杨纯林的枯落物储量稍大于白桦纯林,但二者的枯落物层持水能力相近。

[Objective]To study the stock volume of humus layer and its water conservation effect of typical stand in Saihanwula National Nature Reserve,where a lot of tree died under drought stress caused by climate warming and drying.[Method]Nine plots were selected for each of the pure forests of Populus davidiana and Betula platyphylla.The biomass of humus layer and the water holding capacity of humus layer of the two forests was determined using indoor soaking method.[Result]The results showed that:(1)Under the same canopy density,the total biomass of humus layer of P.davidiana forest was 12.41 t·hm^(-2),higher than that of B.platyphylla forest(10.97 t·hm^(-2)).(2)The maximum water holding capacities of the humus layer of both the forest was 26.85 and 26.77 t·hm^(-2),and the corresponding effective storage capacities were 11.96 and 11.07t·hm^(-2),showing the similar water-holding effect.(3)The relationship between dynamic water holding capacity of humus layer and the soaking time followed a logarithmic function,and the relationship between the water absorption rate and soaking time followed a power function.[Conclusion]This study carried out in the southern section of the Daxing’anling Mountains shows that the humus layer biomass of pure forest of P.davidiana is slightly larger than that of the pure forest of B.platyphylla,but the water holding capacity of humus layer of both the two forests is similar.