Reciprocal relationships between plant diversity and ecosystem productivity (BEF-Loops)

生态学领域的一个主要问题是植物物种丰富度与草地生物量生产的关系。生态学家从两个角度研究了这个问题，即生物量生产驱动植物物种丰富度变化的角度（生产力丰富度关系或PRR），以及假设反向因果关系的角度，植物丰富度驱动植物生产力变化的角度（生物多样性和生态系统功能或BEF角度）。虽然PRR和BEF机制可能共同运作，并且内在相关，但它们通常由代表不同思想流派的不同研究人员分开研究。然而，PRR的关系不能完全理解没有占BEF的关系，反之亦然，从而限制了我们的理解，如何既植物多样性和生物量生产是驱动在草原上的BEF循环项目的目的是比较的相对强度BEF和PRR的关系，在农业草原上的植物多样性和生物量生产之间的整体关系。这将通过结合实验和比较观察沿着土地利用强度梯度在德国。在实验中，与常设生物量去除（放牧和割草），生物量生产（施肥）以及植物多样性相关的因素在同一领域内进行操作，这些操作的影响的相对强度将进行评估。在同样的田地里，将收集未经管理的草地的数据，并使用结构方程模型进行分析，以便调查现存生物量、植物生产力和植物物种丰富度之间的直接和间接关系，以及共变因素（例如土壤肥力、光截获、草地管理）。无论是在实验中，还是在未经处理的草原上，都将在多个季节和年份收集数据，这将有助于区分原因。（发生在较早时间的变化）和后果该项目将为生物多样性勘探站项目提供普遍感兴趣的高质量生产力和养分供应数据，同时也为解决关于植物多样性与生产力关系的性质的长期争论做出了重大贡献。

A major question in the field of ecology is how plant species richness is related to grassland biomass production. Ecologists have studied this question from two perspectives, namely the perspective in which biomass production drives variation in plant species richness (Productivity Richness Relationships or PRR), and the perspective where a reverse causality is assumed, and plant richness drives variation in plant productivity (Biodiversity and Ecosystem Functioning or BEF perspective). While PRR and BEF mechanisms may jointly operate and are inherently related, they are typically studied in separation by different researchers representing different schools of thought. However, PRR relationships cannot be fully understood without accounting for BEF relationships, and vice versa, thus limiting our understanding of how both both plant diversity and biomass production are driven in grasslands.The aim of the BEF-Loops project is to compare the relative strength of BEF and PRR relationships in driving overall relationships between plant diversity and biomass production in agricultural grasslands. This will be done by combining experiments and comparative observations along a land use intensity gradient in Germany. In the experiments, factors related to standing biomass removal (grazing and mowing), biomass production (fertilization) as well as plant diversity are manipulated within the same fields, and the relative strength of the effects of these manipulations will be assessed. Within the same fields, data from unmanipulated grasslands will be collected and analysed using structural equation models in order to investigate the direct and indirect relationships between standing biomass, plant productivity and plant species richness, as well as covarying factors (e.g. soil fertility, light interception, grassland management). In both the experiments and in the unmanipulated grasslands, data will be collected during multiple seasons and years, which will help to distinguish between cause (changes occurring earlier in time) and consequences (changes occurring later in time).This project will provide high quality productivity and nutrient availability data of general interest to the Biodievrsity Exploratories project, while also making a significant contribution to resolving long-running debates about the nature of the plant diversity-productivity relationship.