甘肃兴隆山主要森林类型凋落物累积量及其影响因子

目的]为了阐明森林凋落物累积量与主要影响因子的关系。方法]2013-2014年,采用时空互代法和标准样地调查法,研究了兴隆山山杨-白桦-青杄林演替过程中山杨-白桦-青杄中龄林、青杄中龄林和青杄近熟林3种森林群落凋落物累积量及其主要影响因子。结果]表明:1)随森林正向演替的进行,森林凋落物层厚度和总累积量先减小后增加,3种森林群落凋落物层厚度均值依次为5.26、5.03和5.59 cm,总累积量均值依次为57.08、51.44、56.34 t·hm^-2; 2)随海拔高度的升高,青杄近熟林凋落物总累积量不断增加,海拔2300、2400和2500 m均值依次为48.56、55.93和64.55 t·hm^-2;林分密度大的、坡度小的青杄中龄林凋落物总累积量较大,林分密度为2133、1705和1065株·hm^-2的均值依次为49.87、48.59和45.36 t·hm^-2,坡度为22°、32°和41°的均值依次为58.35、49.90和48.59 t·hm^-2; 3)凋落物未分解层与林分胸径、树高、针叶树密度呈显著相关性。结论]森林凋落物累积量影响因子较多,其大小是众多因子共同作用的结果。在林分和立地因子中,海拔影响较为明显,随海拔高度的升高而不断增加;林分密度、坡度等因子均有影响,但作用不明显;林分胸径、树高、针叶树密度与未分解层累积量呈显著负相关性,而与已分解层呈显著正相关性。

Litter Accumulation and Its Impact Factor of Three Main Forest Communities in Xinglong Mountain, Gansu Province

In order to illustrate the relationship between forest litter cumulants and its key impact factors, the litter accumulation amount and its main environmental factors of three forest communities(middle-aged Populus davidiana-Betula platyphylla-Picea wilosonii forest, middle-aged Picea wilsonii forest and pre-matured P. wilsonii forest)during the succession of Populus davidiana-B. platyphylla-Picea wilosonii forest were studied by using the methods of spatial series representing temporal series and standard sample survey method in 2013-2014 in Xinglong Mountain of Gansu Province. The results showed as follows:1. The thickness and total accumulation amount of litters decreased at first and then increased with the positive succession of forest communities. The average values of thickness for the three forest communities were 5.26 cm, 5.03 cm and 5.59 cm respectively,and the average values of total accumulation amount were 57.08 t·hm^-2, 51.44 t·hm^-2, and 56.34 t·hm^-2. 2. For the pre-matured P. wilsonii forest, the total accumulation amount of litter was gradually increasing with the increase of elevation, and the average values of the three elevations of 2300 m, 2400 m, 2500 m were 48.56 t·hm^-2,55.93 t·hm^-2, and 64.55 t·hm^-2 respectively;For the middle-aged P. wilsonii forest, the total accumulation amount of litter of high density stand and small slope were greater, but the impact of the density and slope on the acumulation amount of litter was not obvious, the average values for the stand densities of 2133 plants·hm^-2, 1705 plants·hm^-2 and 1065 plants·hm^-2 were 49.87 t·hm^-2, 48.59 t·hm^-2 and 45.36 t·hm^-2 respectively,while the average values for the slopes of 22°, 32° and 41° were 58.35 t·hm^-2, 49.9 t·hm^-2 and 48.59 t·hm^-2. 3. The correlation analysis showed that there was a significant correlation among the accumulation amount of litter un-decomposed and DBH, height, conifer density. The enviromental factors affacting the accumulation amount of forest litter were various, and the litter amount was the result of combined action of many factors.