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黄土丘陵区不同降水梯度对草地群落化学计量学特征的影响
郭宁1,2, 姜基春3, 王国强3, 焦峰1,3
1.中国科学院 水利部 水土保持研究所, 陕西 杨凌 712100;2.中国科学院大学, 北京 100049;3.西北农林科技大学 水土保持研究所, 陕西 杨凌 712100
摘要:
[目的] 研究草地群落各组分(植物叶片、根系和土壤)碳氮磷化学计量特征对降水量变化的响应规律,以揭示降水量对黄土丘陵区草地生态系统化学计量学特征的影响。[方法] 以黄土丘陵区自然恢复草地为研究对象,于2017-2018年在安塞试验站建立野外控雨试验平台,分别设置减雨60%,减雨40%,减雨20%,自然降水,增雨20%,增雨40%,增雨60%共7个处理,采用遮雨棚法研究降水改变对植物的叶片、根系以及土壤生态化学计量特征的影响。[结果] ①随降水量增加,植物生长水分限制得到有效缓解,水分胁迫作用逐渐减缓,从而使叶片N,P含量整体呈现显著下降趋势(p<0.05)。叶片C/N,C/P整体呈现显著下降趋势(p<0.05)。②降水梯度改变对根系P化学计量特征影响较为显著(p<0.05);同时,对根系C/P,N/P也有显著影响(p<0.05)。③控雨处理仅对土壤C含量有显著影响(p<0.05),可能因为极端降水影响了土壤微生物的活性,导致土壤有机C积累减缓。[结论] 水分是黄土丘陵区草地植物对N,P吸收利用的制约因子;降水量可以改变草地群落的养分限制格局,随着降水量的增加,植物生长受P的限制越强烈,植物生长由同时受N,P两者的限制转为受P限制。
关键词:  降水梯度  黄土丘陵区  草地群落  化学计量学
DOI:10.13961/j.cnki.stbctb.2020.02.001
分类号:S812.2
基金项目:国家重点研发计划项目"植物-土壤-大气碳氮耦合循环动力学过程"(2016YFA0600801);科技基础性工作专项(2014FY210130)
Effects of Different Precipitation Gradients on Stoichiometric Characteristics of Grassland Communities in Loess Hilly Region
Guo Ning1,2, Jiang Jichun3, Wang Guoqiang3, Jiao Feng1,3
1.Institute of Soil and Water Conservation CAS & MWR, Yangling, Shaanxi 712100, China;2.University of Chinese Academy of Sciences, Beijing 100049, China;3.Institute of Soil and Water Conservation, Northwest A&F University, Yangling, Shaanxi 712100, China
Abstract:
[Objective] The response of carbon, nitrogen and phosphorus of each component (plant leaves, roots and soil) of grassland community to precipitation change was studied, in order to reveal the influence of precipitation on the stoichiometric characteristics of grassland ecosystem in loess hilly region.[Methods] The natural restored grassland in loess hilly region was taken as the research object, a field rain control test platform was established at Ansai experimental station during 2017-2018, with 7 treatments including 60% rain reduction, 40% rain reduction, 20% rain reduction, natural precipitation, 20% rain increase, 40% rain increase, and 60% rain increase. The canopy method was adopted to study the influence of precipitation change on the leaves, roots and soil ecological stoichiometric characteristics of plants.[Results] ① With the increase of precipitation, the water restriction in plant growth was effectively alleviated, and the effect of water stress gradually slowed down, so that the N and P contents in leaves showed a significant decline (p<0.05). And the C/N and C/P of the leaves also showed a significant downward trend (p<0.05). ② The change of precipitation gradient had a significant effect on the P contents of root system (p<0.05). The change of precipitation gradient had significant influence on root C/P and N/P (p<0.05). ③ Rain control treatment only had significant effect on soil C content (p<0.05), which may be because extreme precipitation affected the activity of soil microorganisms, resulting in a slow accumulation of soil organic C.[Conclusion] Water is the limiting factor for the absorption and utilization of N and P by grassland plants in loess hilly region. Precipitation can change the nutrient restriction pattern of grassland community. With the increase of precipitation, plant growth is more restricted by P, and plant growth will changed from being restricted by both N and P to being restricted by P.
Key words:  precipitation gradient  loess hilly region  grassland community  stoichiometry