沙坡头地区草本植物层片对施加氮素的响应

以沙坡头人工固沙区草本层片植物为研究对象,分析不同氮肥处理下,物种丰富度、多度、盖度、高生长以及地上部生物量等群落学特征对不同氮肥水平的响应。人工施加氮肥1年的试验结果表明:除50g·m-2的施肥水平外,其他各施肥水平下群落物种丰富度均高于对照;多度随施肥梯度的增加整体上呈下降趋势,施肥梯度越高,下降越明显,其中在50g·m-2的施肥水平下,多度相比于对照下降了86.7%;盖度随施肥水平梯度的增大呈先上升后下降的趋势,在20g·m-2的施肥水平下盖度达到最大值,其与对照间的差异达到了显著性水平(P<0.05);植物高生长对氮肥水平的响应存在种间差异;地上部生物量则在低肥水平下高于对照,而高肥水平下低于对照。总体而言,氮肥水平对荒漠生态系统群落物种多样性和生产力的影响呈低肥促进、高肥抑制的效应。

Responses of herbaceous layer vegetation to nitrogen fertilization in Shapotou Area

Taking the herbaceous layer vegetation in Shapotou area as test object,this paper studied its species richness,abundance,coverage,height growth,and aboveground biomass under effects of different nitrogen(N)fertilization levels.One-year observation showed that comparing with the control,all N fertilization treatments except 50 g N·m~(-2) had positive effects on the species richness.With increasing N fertilization level,the species abundance decreased,with a decrement of 86.7% in treatment 50 g N·m~(-2),and the species coverage decreased after an initial increase,with the maximum in treatment 20 g N·m~(-2) and having a significant difference(P<0.05)with the control.The responses of height growth to N fertilization levels varied with plant species.Aboveground biomass wag higher at low N fertilization level but lower at high fertilization level.In a word,low N fertilization level benefited the community biodiversity and productivity,while high N fertilization level had restriction effects.