Dormann Carsten F, von Riedmatten Lars, Scherer-Lorenzen Michael
Biometry & Environmental System Analysis, University of Freiburg, Tennenbacher Str. 4, 79106, Freiburg, Germany.
Computational Landscape Ecology, Helmholtz-Centre for Environmental Research, Permoser Str. 15, 04318, Leipzig, Germany.
BMC Ecol. 2017 Jun 17;17(1):23. doi: 10.1186/s12898-017-0133-0.
Species richness affects processes and functions in many ecosystems. Since management of temperate grasslands is directly affecting species composition and richness, it can indirectly govern how systems respond to fluctuations in environmental conditions. Our aim in this study was to investigate whether species richness in managed grasslands can buffer the effects of drought and warming manipulations and hence increase the resistance to climate change. We established 45 plots in three regions across Germany, each with three different management regimes (pasture, meadow and mown pasture). We manipulated spring warming using open-top chambers and summer drought using rain-out shelters for 4 weeks.
Measurements of species richness, above- and below-ground biomass and soil carbon and nitrogen concentrations showed significant but inconsistent differences among regions, managements and manipulations. We detected a three-way interaction between species richness, management and region, indicating that our study design was sensitive enough to detect even intricate effects.
We could not detect a pervasive effect of species richness on biomass differences between treatments and controls, indicating that a combination of spring warming and summer drought effects on grassland systems are not consistently moderated by species richness. We attribute this to the relatively high number of species even at low richness levels, which already provides the complementarity required for positive biodiversity-ecosystem functioning relationships. A review of the literature also indicates that climate manipulations largely fail to show richness-buffering, while natural experiments do, suggesting that such manipulations are milder than reality or incur treatment artefacts.
物种丰富度影响许多生态系统中的过程和功能。由于温带草原的管理直接影响物种组成和丰富度，它可以间接控制生态系统对环境条件波动的响应方式。我们这项研究的目的是调查管理草原中的物种丰富度是否能够缓冲干旱和变暖处理的影响，从而增强对气候变化的抵抗力。我们在德国的三个地区建立了45个样地，每个样地有三种不同的管理制度（牧场、草地和割草场）。我们使用开顶式气室控制春季变暖，使用遮雨棚控制夏季干旱，为期4周。
对物种丰富度、地上和地下生物量以及土壤碳氮浓度的测量表明，不同地区、管理方式和处理之间存在显著但不一致的差异。我们检测到物种丰富度、管理方式和地区之间存在三向交互作用，这表明我们的研究设计足够灵敏，能够检测到即使是复杂的影响。
我们没有检测到物种丰富度对处理组和对照组之间生物量差异的普遍影响，这表明春季变暖和夏季干旱对草地系统的综合影响并没有被物种丰富度一致地调节。我们将此归因于即使在低丰富度水平下也有相对较多的物种，这已经提供了积极的生物多样性与生态系统功能关系所需的互补性。对文献的综述还表明，气候处理大多未能显示出丰富度缓冲作用，而自然实验则显示出这种作用，这表明此类处理比实际情况温和，或者会产生处理假象。
