Species richness, temporal variability and resistance of biomass production in a Mediterranean grassland
Species richness, temporal variability and resistance of biomass production in a Mediterranean grassland
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DOI：
10.1111/j.0030-1299.2005.13873.x
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发表时间：
2005-07-01
期刊：
影响因子：
3.4
通讯作者：
Pereira, JS
中科院分区：
文献类型：
--
作者：
Caldeira, MC;Hector, A;Pereira, JS
我们从一个实验性的多样性梯度(葡萄牙BioDepth项目点)研究了草原群落生物量生产的时间变异性和对扰动的抵抗力。随着物种丰富度的增加，植物种群的相对时间变异性(CV)增大，而群落的相对时间变异性(CV)减小，支持保险假说及相关理论。物种丰富的群落在所有三年都比物种贫乏的群落更具生产力，尽管第三年的自然气候扰动(霜冻频繁和降雨量少)导致生物量生产总体下降。在实验物种丰富度梯度中，对这种扰动的抵抗力在相对范围内是恒定的，支持瑞士BioDepth实验的类似反应。不同年份的互补效应和选择效应的不同组合产生了正的生物量响应。在所有三年的混合中，互补效应平均为正，并且与一个季节的多样性呈正相关。在与总生物量一致的扰动之后，互补效应下降，但与预测相反，相对超产在所有年份都保持着。选择效应在一年内与多样性呈正相关，在其他两年总体上与多样性呈负相关。不同树种以及同一树种在单一栽培和混合栽培条件下对扰动的反应不同，但霜冻后群落更多地被单一栽培生物量较低的物种所支配，选择效应较负。总体而言，我们的结果支持了以前的发现，即多样性与生产力以及多样性与生产的时间稳定性之间存在正相关关系，但多样性对抗扰性没有影响。我们首次证明了在异常的自然环境扰动中，过度屈服的相对强度保持不变。
We studied the temporal variability and resistance to perturbation of the biomass production of grassland communities from an experimental diversity gradient (the Portuguese BIODEPTH project site). With increasing species richness relative temporal variability (CV) of plant populations increased but that of communities decreased, supporting the insurance hypothesis and related theory. Species-rich communities were more productive than species-poor communities in all three years although a natural climatic perturbation in the third year (frequent frost and low precipitation) caused an overall decrease in biomass production. Resistance to this perturbation was constant across the experimental species richness gradient in relative terms, supporting a similar response from the Swiss BIODEPTH experiment. The positive biomass response was generated by different combinations of the complementarity and selection effects in different years. Complementarity effects were positive across mixtures on average in all three years and positively related to diversity in one season. The complementarity effect declined following perturbation in line with total biomass but, counter to predictions, in relative terms overyielding was maintained in all years. Selection effects were positively related to diversity in one year and negative overall in the other two years. The response to perturbation varied among species and for the same species growing in monoculture and mixture, but following the frost communities were more strongly dominated by species with lower monoculture biomass and the selection effect was more negative. In total, our results support previous findings of a positive relationship between diversity and productivity and between diversity and the temporal stability of production, but of no effect of diversity on the resistance to perturbation. We demonstrate for the first time that the relative strength of overyielding remained constant during an exceptional natural environmental perturbation.