Summer rain pulses may stimulate a CO2 release rather than absorption in desert halophyte communities
Summer rain pulses may stimulate a CO2 release rather than absorption in desert halophyte communities
复制标题
夏季降雨脉冲可能会刺激沙漠盐生植物群落释放而不是吸收二氧化碳
DOI：
10.1007/s11104-013-1839-1
复制
发表时间：
2013-12-01
期刊：
影响因子：
4.9
通讯作者：
Li, Yan
中科院分区：
文献类型：
--
作者：
Liu, Ran;Cieraad, Ellen;Li, Yan
在干旱和半干旱地区，植物和土壤对降雨脉冲的响应决定了生态系统尺度上物质和能量交换的季节变化。我们评估了不同植物功能类型的荒漠盐生植物群落的生态系统碳交换（NEE）如何响应夏季降雨脉冲，在柽柳和梭梭群落中。通过对梭梭土壤呼吸和生态系统净碳交换的测定，验证了梭梭对夏季降水的高生理敏感性可能导致其NEE发生较大变化的假设结果植物水分状况和光合作用同化没有差异之前和之后的夏季降水脉冲在两个社区。相反，土壤呼吸和NEE强烈响应夏季降水事件在两个社区。在生态系统一级，降水脉冲引起CO2释放脉冲，而不是吸收。深根柽柳群落对夏季降水的NEE响应小于浅根梭梭群落，梭梭群落在夏季降水输入后甚至转化为碳源。因此，夏季降水输入对土壤呼吸的影响比植物（碳同化）的反应更重要，在决定生态系统响应的情景降水脉冲。
Background and aimsThe response of plants and soil to rain pulses determines seasonal variations in the exchange of materials and energy at the ecosystem scale in arid and semi-arid regions. We assessed how the ecosystem carbon exchange (NEE) of desert halophyte communities of different plant functional-types responds to summer precipitation pulses in Tamarix and Haloxylon communities.MethodsPlant water status, photosynthetic gas exchange, soil respiration and net ecosystem carbon exchange were measured to test the hypothesis that high physiological sensitivity may induce a greater changes in NEE resulting from the summer precipitation pulses in Haloxylon community.ResultsPlant water status and photosynthetic assimilation did not differ before and after summer precipitation pulses in either community. In contrast, soil respiration and NEE responded strongly to summer precipitation events in both communities. At the ecosystem level, precipitation pulses induced a pulse of CO2 release, rather than absorption. The NEE response to summer precipitation was less in the deep-rooted Tamarix community, compared to the shallow-rooted Haloxylon community, which was even converted into a carbon source after summer precipitation inputs. As a result, the effect of summer precipitation inputs on soil respiration was more important than the plant (carbon assimilation) response in determining the ecosystem response to episodic precipitation pulses.