氮素输入对呼伦贝尔草甸草原植物群落氮磷化学计量特征的影响  

Effects of nitrogen inputs on plant community N:P stoichiometry of a meadow steppe in Hulunbuir

作　　者：陈友余 杨国姣 梁潇洒 丁聪 胡艳宇 杨雁茹 张志委 吕晓涛[1] CHEN Yuo-yu;YANG Guo-jiao;LIANG Xiao-sa;DING Cong;HU Yan-yu;YANG Yan-ru;ZHANG Zhi-wei;LÜXiao-tao(Erguna Forest-Steppe Ecotone Research Station,Institute of Applied Ecology,Chinese Acad-emy of Sciences,Shenyang 110016,China;College of Resources and Environment,University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院沈阳应用生态研究所额尔古纳森林草原过渡带生态系统研究站,沈阳110016 [2]中国科学院大学资源与环境学院,北京100049

出　　处：《生态学杂志》2022年第8期1517-1524,共8页Chinese Journal of Ecology

基　　金：国家自然科学基金项目(31770503)资助。

摘　　要：植物群落水平的养分特征是调控生态系统过程的重要因素。大气氮沉降通过改变植物群落物种组成的种间变化过程和改变植物物种水平养分特征的种内变化过程来影响群落水平养分特征。明确上述两种过程的相对重要性对于预测生态系统功能的变化具有重要意义。本研究依托野外氮素添加实验,分析了氮素输入对于呼伦贝尔草甸草原群落水平氮磷化学计量特征的影响,并分析了两种过程的相对贡献。结果表明:在0~50 g N·m^(-2)·a^(-1)的氮素输入量梯度上,植物群落组成发生明显变化。所关注的17种植物中,8种植物的氮含量与氮素输入量呈显著正相关,而大多数物种的磷含量和N∶P对氮素输入不敏感。随氮素输入量的增加,植物群落水平的氮含量和N∶P均显著升高,而磷含量则无显著变化。氮素输入所引起的群落水平上植物养分特征的变化主要是由于种内变化过程所导致;其对于氮含量、磷含量和N∶P变化的贡献率分别为75%~99%、61%~91%和97%~100%。研究表明:(1)草甸草原生态系统中植物氮磷化学计量特征对于氮素输入的响应具有较强的物种特异性;(2)尽管植物群落组成与结构对于氮素输入非常敏感,但群落水平上氮磷化学计量特征的改变主要是由少数优势物种的种内水平上养分特征变化所导致的。Plant nutritional traits at the community-level are important drivers for several fundamental ecosystem processes. Effects of nitrogen deposition on the community-level stoichiometric characteristics are co-driven by interspecific variability(species turnover) and intraspecific trait variability(ITV;nutritional changes of each species). Hence, specifying the relative importance of those two processes is critically needed for predicting the alternations of ecosystem functioning. Based on a 6-year N addition experiment in a meadow steppe of Hulunbuir, we examined the relative contribution of those two processes to the changes of community-level N and P concentrations and N∶P stoichiometry in response to N enrichment. Results showed that plant community composition significantly varied along the N addition rate gradient(from 0 to 50 g N·m·a). Out of the 17 examined species, eight species showed positive responses of N concentration to N inputs, while P concentrations and N∶P ratios in most species were not sensitive to N inputs. The community-level N concentration and N∶P ratio significantly increased with increasing N addition rates, while community-level P concentration remained unchanged. The N-induced alternations of community-level nutritional traits were mainly caused by ITV, which accounted for 75%-99%, 61%-91%, and 97%-100% of the total variation in community-level N concentration, P concentration, and N∶P, respectively. Our results indicated that(1) the responses of plant N∶P stoichiometry to N input were highly species-specific in the meadow steppe;and(2) while plant community composition and structure were quite sensitive to N inputs, changes of community-level nutritional traits were largely resulted from the ITV of a few dominant species.

关 键 词：群落组成 生态化学计量学 种内变化 氮沉降 半干旱草原 

分 类 号：S812[农业科学—草业科学]