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N添加对宁夏荒漠草原植物和土壤C∶N∶P生态化学计量特征的影响

黄菊莹1**,赖荣生2,余海龙2,陈卫民1   

  1. (1宁夏大学新技术应用研究开发中心, 银川 750021; 2宁夏大学资源环境学院, 银川 750021)
  • 出版日期:2013-11-10 发布日期:2013-11-10

Responses of plant and soil C∶N∶P stoichiometry to N addition in a desert steppe of Ningxia, Northwest China.

HUANG Ju-ying1**, LAI Rong-sheng2, YU Hai-long2, CHEN Wei-min1   

  1. (1Development Center of New Technique Application and Research, Ningxia University, Yinchuan 750021, China; 2College of Resources and Environment, Ningxia University, Yinchuan 750021, China)
  • Online:2013-11-10 Published:2013-11-10

摘要: 研究N添加对植物和土壤C、N、P生态化学计量学特征的影响,对于认识生态系统生物地球化学循环如何响应N沉降增加具有重要意义。本研究开展宁夏荒漠草原的N添加野外试验,研究N添加对4个物种C、N计量特征、土壤C、N和P计量特征的影响,分析N限制相关的土壤计量特征与植物计量特征的相关性。结果表明,随着N供给量增加,群落地上生物量和物种个体生物量均呈先增加后降低的趋势;4个物种叶片C浓度无明显的变化规律,除冰草之外的其他3个物种叶片N浓度显著增加,牛枝子和老瓜头叶片C∶N显著降低;土壤全N显著增加,而其他土壤指标对N添加的响应不存在明显的规律性;老瓜头个体生物量与土壤全N和N∶P呈正相关,冰草和老瓜头叶片全N与土壤全N呈正相关,针茅和老瓜头叶片C∶N与土壤全N呈负相关。表明,短期N添加对荒漠草原土壤C、N、P及其计量比的影响较小,但一定程度上缓解了荒漠草原N限制,因此提高了绿叶N摄取,促进了植物生物量积累和枯叶分解质量。同时,其影响又表现出一定的物种差异性,这不仅反映了植物对环境变化的弹性适应,也意味着长期N沉降增加可能会改变荒漠草原生态系统的结构。

关键词: 兴安落叶松, 空间分布格局, 尺度, 白桦

Abstract: To study the effects of nitrogen (N) addition on the plant and soil C∶N∶P stoichiometry is of significance in understanding the responses of ecosystem biogeochemical cycling to elevated N deposition. In this paper, a field experiment was conducted in a desert steppe of Ningxia to study the effects of N addition on C and N concentrations in green leaves of Agropyron cristatum, Stipa capillata, Lespedeza potanimill, and Cynanchum komarovii, and C, N and P concentrations in soil, with the relationships between the N limitation related plant and soil stoichiometry analyzed. The results showed that with the increasing amount of N addition, the community aboveground biomass and species individual biomass all decreased after an initial increase. The C concentration in the green leaves of the four species had no obvious variation pattern, the N concentration in the green leaves of the four species except A. cristatum had a significant increase, while the C∶N ratio in the green leaves of L. potanimil and C. komarovii decreased significantly. The soil total N content increased significantly, while the other soil indices had no significant responses to N addition. The individual biomass of C. komarovii had positive correlations with soil N and N∶P ratio, the N concentration in green leaves of A. cristatum and C. komarovii was positively correlated with soil N, while the C∶N ratios in the green leaves of S. capillata and C. komarovii were negatively correlated with soil total N. Our results indicated that shortterm N addition had little effects on the soil C∶N∶P stoichiometry but relieved the N limitation of plant growth in desert grassland to a certain extent, and thus, increased the N uptake by green leaves, promoted the biomass accumulation of plant, and improved the leaf litter decomposition quality. These species-specific responses not only reflect flexible adaptation to environment change, but also mean that long-term elevated N deposition may change the structure of desert steppe ecosystem.

Key words: Larix gmelinii, spatial distribution pattern,  , Betula platyphylla, scale.