Drought alters carbon fluxes in alpine snowbed ecosystems through contrasting impacts on graminoids and forbs
Drought alters carbon fluxes in alpine snowbed ecosystems through contrasting impacts on graminoids and forbs
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DOI：
10.1111/j.1469-8137.2010.03613.x
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发表时间：
2011-01-01
期刊：
影响因子：
9.4
通讯作者：
Helliwell, Rachel C.
中科院分区：
文献类型：
--
作者：
Johnson, David;Vachon, Jeremie;Helliwell, Rachel C.
据预测，气候变化将增加高山生态系统中干旱事件的频率，并有可能影响碳周转。我们从纳尔杜斯·斯特里塔高山雪地群落中移除了完整的草坪，并在受控条件下对其中一半进行了为期8天的两次干旱事件。在整个6wk研究期间，渗滤液溶解有机碳(DOC)被测量，13CO(2)脉冲能够量化新近同化物质进入地上部、根和渗滤液的通量以及生态系统的CO2交换。干旱降低了禾本科植物生物量，增加了杂草生物量，对苔藓植物没有影响，导致地上总生物量与对照相比总体下降。干旱草坪的净CO2交换、总光合作用和13CO(2)固定量均显著低于对照。这些草坪还保留了更多的13C在地上部，分配到根中的13C较少，渗滤液中的溶解有机13C的回收率比对照减少了57%。我们的数据表明，干旱事件对生态系统碳通量有显著影响，其背后的主要机制可能是杂草和牧草相对丰度的变化。
P>Climate change is predicted to increase the frequency of drought events in alpine ecosystems with the potential to affect carbon turnover.We removed intact turfs from a Nardus stricta alpine snowbed community and subjected half of them to two drought events of 8 d duration under controlled conditions. Leachate dissolved organic carbon (DOC) was measured throughout the 6 wk study period, and a 13CO(2) pulse enabled quantification of fluxes of recent assimilate into shoots, roots and leachate and ecosystem CO2 exchange.The amount of DOC in leachate from droughted cores was 62% less than in controls. Drought reduced graminoid biomass, increased forb biomass, had no effect on bryophytes, and led to an overall decrease in total above-ground biomass compared with controls. Net CO2 exchange, gross photosynthesis and the amount of 13CO(2) fixed were all significantly less in droughted turfs. These turfs also retained proportionally more 13C in shoots, allocated less 13C to roots, and the amount of dissolved organic 13C recovered in leachate was 57% less than in controls.Our data show that drought events can have significant impacts on ecosystem carbon fluxes, and that the principal mechanism behind this is probably changes in the relative abundance of forbs and grasses.