模拟氮沉降对温带草原凋落物质量的影响

Effect of simulated nitrogen deposition on litter quality in a temperate grassland

基于6年模拟氮沉降试验平台研究了氮沉降对温带草原凋落物质量的影响。采集对照(0 g N·m^(-2)·a^(-1))、低氮(5 g N·m^(-2)·a^(-1))、中氮(10 g N·m-2·a-1)和高氮(15g N·m^(-2)·a^(-1))4个氮添加梯度,混合和单一两种凋落物类型,测定了凋落物纤维素、半纤维素、木质素、全碳、全氮和全磷含量。结果表明:长期模拟氮沉降降低了2种凋落物中纤维素、半纤维素、木质素含量及其与N素的比值;氮沉降对凋落物C含量无明显影响,降低了凋落物N、P含量以及C/N和C/P比值。由于氮沉降增加了凋落物N、P元素含量,同时降低了难分解的结构性物质含量,因此可能会对凋落物分解产生促进作用。

Based on a 6-year simulation N deposition experiment, we investigated the effects of N deposition on the litter quality in a temperate grassland. Mixed and mono-specific litter from four N treatments, including control （0 g N ·m^-2·a^-1 ） , low nitrogen （ 5 g N ·m^-2·a^-1 ）, medium nitrogen （10 g N ·m^-2·a^-1）, and high nitrogen （15 g N·m^-2·a^-1） were collected. The basic properties of litter quality （ concentrations of cellulose, hemicellulos, lignin, C, N and P） were measured. The results indicated that N deposition decreased the concentration of cellulose, hemicellulos and lignin in litter, while increased the N and P concentration. The effect of N deposition on the concentration of C was not significant. The ratios of C/N and C/P were decreased by N deposition. Our results suggest that the litter decomposition rate may be stimulated by simulated N deposition due to the increase of N and P concentration and decrease of structural carbohydrate and lignin in plant litter.