Increased rainfall variability reduces biomass and forage quality of temperate grassland largely independent of mowing frequency
Increased rainfall variability reduces biomass and forage quality of temperate grassland largely independent of mowing frequency
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DOI：
10.1016/j.agee.2011.11.015
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发表时间：
2012-02
期刊：
影响因子：
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通讯作者：
J. Walter;Kerstin Grant;C. Beierkuhnlein;J. Kreyling;Michael Weber;A. Jentsch
中科院分区：
文献类型：
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作者：
J. Walter;Kerstin Grant;C. Beierkuhnlein;J. Kreyling;Michael Weber;A. Jentsch
气候模型表明，全球变暖将刺激大气交换过程，增加降雨量的变化，导致干旱期延长和降雨量增加。最近的研究表明，无论是降雨事件的规模和频率可能是一样重要的温带草原生产力的年度总和。然而，到目前为止，土地管理措施，如割草频率和降雨量的变化对生产力和牧草质量之间的相互作用还没有详细研究。在这里，我们提出了一个现场实验（事件II）的数据，中欧草原受到春季降雨量的变化增加（低，中等和极端降雨量的变化没有任何变化的降雨量）和割草频率增加（四倍相比，每年两次）。我们评估了生物量生产，牧草质量参数，根长和冠根比。增强春季降雨量的变化减少仲夏生产力和叶片N和蛋白质浓度的目标物种，但没有施加任何长期的影响，生物量生产和牧草质量在夏末。然而，增加春季降雨变率减少地上净初级生产力的15%。在研究的第一年，更频繁的割草增加了生产力，但在第二年年底降低了生产力，这表明在经历了更激烈的割草之后，过度补偿的潜力有所下降。总体而言，更频繁的割草降低了茎根比，提高了叶片氮浓度。增加割草频率既不缓冲，也不放大降雨变异对生产力的不利影响，但叶氮浓度在初夏更响应改变降雨模式。这些结果突出了这样一个事实，即使是相对较小的和短期的降雨分布的变化，可以降低生产和饲料质量，改变割草频率的缓冲能力很小。从研究的第一年，其中，降雨分布和降雨量进行了修改，生产力数据的比较，证明了足够的水分（年降雨量）草地恢复力的关键作用：在这第一年，极端降雨变异的负面影响持续到年底。总之，气候变化下的降雨量变化可能会影响温带草甸的农业产量。缓冲这些影响的管理战略尚待制定。
Climate models indicate that global warming will stimulate atmospheric exchange processes and increase rainfall variability, leading to longer dry periods and more intense rainfall events. Recent studies suggest that both the magnitude of the rainfall events and their frequency may be as important for temperate grassland productivity as the annual sum. However, until now interactive effects between land management practice, such as mowing frequency, and rainfall variability on productivity and forage quality have not been studied in detail. Here, we present the data from a field experiment (EVENT II) in which a Central-European grassland was subjected to increased spring rainfall variability (low, intermediate and extreme rainfall variability without any change to the rainfall amount) and increased mowing frequency (four times compared to twice a year). We assessed biomass production, forage quality parameters, root-length and shoot–root ratio. Enhanced spring rainfall variability reduced midsummer productivity and the leaf N and protein concentrations of a target species, but did not exert any long-term effects on biomass production and forage quality in late summer. However, the increased spring rainfall variability reduced aboveground net primary productivity by 15%. More frequent mowing increased productivity in the first year of the study, but decreased productivity at the end of the second year, showing a decline in the potential for overcompensation after a history of more intense mowing. Generally, more frequent mowing decreased the shoot–root ratio and increased the concentration of leaf N. Increased mowing frequency neither buffered, nor amplified the adverse effects of rainfall variability on productivity, but made leaf N concentrations in early summer more responsive to altered rainfall patterns. These results highlight the fact that even relatively small and short-term alterations to rainfall distribution can reduce production and forage quality, with little buffering capacity of altered mowing frequency. Comparisons with productivity data from the first year of the study, in which both, rainfall distribution and rainfall amount were modified, demonstrate the crucial role of sufficient moisture (annual rainfall amount) for grassland resilience: in this first year, negative effects of extreme rainfall variability lasted until the end of the year. To conclude, increased rainfall variability under climate change will likely affect agricultural yield in temperate meadows. Management strategies to buffer these effects have yet to be developed.