甘肃小陇山不同针叶林凋落物量、养分储量及持水特性

通过野外实地观测和室内分析相结合的方法对甘肃小陇山地区6种主要针叶林凋落物层的蓄积量、持水特性及养分储量进行了调查,结果表明:云杉林凋落物层的蓄积量最大,松林次之,落叶松林最小。同一林分林下半分解层凋落物的持水能力比分解层强;在不同林分类型中,凋落物层的最大持水率、最大拦蓄率和有效拦蓄率的大小顺序为:落叶松林>松林>云杉林,而最大拦蓄量和有效拦蓄量的大小顺序为:云杉林>松林>落叶松林。同一林分类型中,分解层凋落物中养分储量最多,未分解层最少;不同林分类型中各个营养元素的储量均表现出:云杉林>松林>落叶松林。凋落物蓄积量与营养元素储量密切相关,最大持水量与凋落物储量和凋落物层各元素储量之间呈显著的正相关性。

Litter amount and its nutrient storage and water holding characteristics under different coniferous forest types in Xiaolong Mountain,Gansu Province

Litterfall layer is the key interface between substance cycling and energy transformation, and also it plays a significant hydro-ecological role in forest ecosystems. This study was conducted at Shaba Forest Experimental Station of the West Qinling Mountain located in Xiaolong Mountain,Gansu Province. Based on the field investigation and controlled environments,the storage of litter and water holding characteristics and nutrient element storages of the litter layer under different stand types of coniferous forest were surveyed after clear-cutting a primary forest in the arid region of the north-west. The results showed that the annual storages of litter ranged from 2.96 t · hm^-2 · a^-1 to 4.23 t · hm^-2 · a^-1 in the coniferous forest stands of Xiaolong Mountains. The storages of litter under different stands of coniferous forest decreased by order of spruce forest > pinus forest > larch forest. Under the same stands of coniferous forest the litterfall in the un-decomposed layer(U layer) accounted for 6%-19%, which was the least among different decomposed layers,whereas the total litterfall in the semi-decomposed and decomposed layers accounted for more than 80%.The water holding capacity of the litter in the semi-decomposed layer was greater than that in the decomposed layer under the same stand of coniferous forest. The maximum water holding rate,max interception rate and modified interception rate of the litter under stands of different coniferous forests were ranked in order larch stand> pinus stand > spruce stand,but the capacity of maximum interception and the modified interception were opposite as compared to the former order. The accumulation of nutrients in the litter layer under the same stand of coniferous forest showed an order of un-decomposed layer(U layer)< semi-decomposed layer(S layer)< decomposed layer(D layer). The nutrient element storages under different stands of coniferous forest were ranked in order spruce forest > pinus forest > larch forest. The property of litter with the different tree species and forest management practices had significant effect on the decomposition rates of litter layers; the decomposition rate of forest litter increased by an order of larch forest > pinus forest > spruce forest. The average storage of nutrient elements in the litter layer with different species was ranked in order Ca>N>Fe>Mg>K>P. The storage of litter is closely related to nutrient element storages in litterfall layer. There was a significantly positive correlation among the capacity of maximum water holding,the litter storage and nutrient element storages in litter layers. The study provides an important basic theories that can be used for breeding and management of forests in the Qinling Western Mountain regions and improving the understanding of hydro-ecological effects in these forestss.