黄土丘陵区华北落叶松人工林生态系统生物量与养分循环特征

通过样地调查观测和室内样品分析,对位于山西吉县的23年生华北落叶松人工林生态系统中13种元素的循环特征进行研究。测算得到研究区域人工林生态系统的生物量在各器官的空间分布,结合林木各器官养分含量,得出养分元素在空间变异上的积累与分布;测算四大分室(林木、土壤、枯落物和大气)中其余分室的养分含量和养分积累与分布,得到养分循环过程中华北落叶松人工林养分年归还量134.719kg/(hm~2·a),年存留量53.409kg/(hm~2·a)和年吸收量188.129kg/(hm2·a);最后综合上述的各分室养分循环状况,得出反映该森林生态系统的养分生物循环特征的参数和指标。研究区华北落叶松人工林生态系统内N,P,K的循环系数均值(0.68),表明研究区生态系统循环速率较快;利用系数偏小,储存效率慢,土壤养分利用效率较高;养分元素通过林冠后均明显增加(林冠截留量142.1mm),并且对降水量(587.8mm)要求一般。较高的富集系数使其适应瘠薄自然环境,养分消耗量低。总体来看,华北落叶松是很有潜力的森林更新和荒山造林树种。

Characteristics of Nutrient Cycling and Ecosystem Structure of Larix principis-rupprechtii in Hilly Loess Plateau

Cycling symbol of thirteen nutrient elements in ecosystem of 23-year-old plantation of Larix principis-rupprechtii in Jixian County,Shanxi Province was studied through survey of sample plots and indoor sample analysis.Spatial distribution of biomass in different organs of plantation ecosystem in the study area was measured,the accumulation and distribution of nutrient elements in spatial variation combining with organ nutrient content of trees were obtained;nutrient content and nutrient accumulation & distribution of other chambers of the four major chambers (forest,soil,litter and atmosphere) were measured to obtain annual nutrient return of Larix principis-rupprechtii plantation in nutrient cycling of 134.719 kg/(hm2 · a),annual storage of 53.409 kg/(hm2 · a) and annual absorption capacity of 188.129 kg/(hm2 · a);at last,in summary of nutrient cycling in above chambers,parameters and indicators reflecting characteristics of nutribent biological cycle of the forest ecosystem were obtained.Average cycle coefficient of N,P,K in plantation ecosystem of Larix principis-rupprechtii in the study area was 0.68,revealing that cycling of ecosystem in the study area was faster;utilization coefficient was small,storage efficiency was slow and soil nutrient use efficiencywas higher;nutrient elements that passed through canopy significantly increased (canopy interception of 142.1 mm),with normal requirement on precipitation (587.8 mm).Higher enrichment factor enabled it to adapt to barren environment with low nutrient consumption.As a whole,Larix principis-rupprechtii is of great potential for forest regeneration and afforestation.