Effects of water and nitrogen addition on ecosystem carbon exchange in a meadow steppe.
Effects of water and nitrogen addition on ecosystem carbon exchange in a meadow steppe.
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DOI：
10.1371/journal.pone.0127695
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发表时间：
2015
期刊：
影响因子：
3.7
通讯作者：
Wang D
中科院分区：
文献类型：
--
作者：
Wang Y;Jiang Q;Yang Z;Sun W;Wang D
一个不断变化的降水制度和增加氮沉降可能会对干旱和半干旱生态系统的碳循环，这往往是由时间和水和氮的可用性的深刻影响。然而，很少有人知道改变降水和氮添加对草地生态系统C交换的影响。我们进行了为期3年的田间试验，以评估植被组成，生态系统生产力和生态系统C交换的响应，以控制水和氮添加在草甸草原。氮素的添加显著促进了草甸草原地上生物量和生态系统CO2净交换，表明氮素有效性是草甸草原生态系统碳循环的主要限制因子。水的增加没有显着的影响，无论是生态系统C交换或植物生物量，但生态系统C通量表现出较强的相关性与早期生长季降水，而不是整个生长季降水，在3个实验年。将水量加入到降水状况的计算中后，我们发现月平均生态系统碳通量与降水频率的相关性比与降水量的相关性更强。这些结果突出了降水分配在调节生态系统碳循环中的重要性。总体而言，在所研究的生态系统中，生态系统C通量是高度敏感的氮沉降，但不太敏感的降水增加。
A changing precipitation regime and increasing nitrogen deposition are likely to have profound impacts on arid and semiarid ecosystem C cycling, which is often constrained by the timing and availability of water and nitrogen. However, little is known about the effects of altered precipitation and nitrogen addition on grassland ecosystem C exchange. We conducted a 3-year field experiment to assess the responses of vegetation composition, ecosystem productivity, and ecosystem C exchange to manipulative water and nitrogen addition in a meadow steppe. Nitrogen addition significantly stimulated aboveground biomass and net ecosystem CO2 exchange (NEE), which suggests that nitrogen availability is a primary limiting factor for ecosystem C cycling in the meadow steppe. Water addition had no significant impacts on either ecosystem C exchange or plant biomass, but ecosystem C fluxes showed a strong correlation with early growing season precipitation, rather than whole growing season precipitation, across the 3 experimental years. After we incorporated water addition into the calculation of precipitation regimes, we found that monthly average ecosystem C fluxes correlated more strongly with precipitation frequency than with precipitation amount. These results highlight the importance of precipitation distribution in regulating ecosystem C cycling. Overall, ecosystem C fluxes in the studied ecosystem are highly sensitive to nitrogen deposition, but less sensitive to increased precipitation.
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