The effect of land-use related diversity on plant-soil feedbacks and plant-community coexistence

从我们以前的温室实验中使用的土壤群落的生物多样性探索的结果表明，土壤生物区系的影响沿着土地利用强度梯度有助于物种共存的影响植物物种优势在草原社区。在我们的实验中，土地利用相关的土壤生物区系的影响不同，尤其是草和草本植物，这表明生物遗产的影响，土地利用植物群落组成和共存的草原。然而，在温室和田间条件下比较植物-土壤反馈（PSF）时，我们在最近的一系列实验中发现PSF效应之间存在一致的差异。在该领域，我们观察到植物多样性对生物反馈的积极影响。这突出了考虑土地利用相关的多样性效应的重要性，因为植物多样性可能会在自然植被中产生间接和不可传递的竞争效应。生物多样性探索中心以前的研究结果清楚地表明，土地利用强度影响到不同营养水平（植物、食草动物、病原体）的多样性。因此，我们想利用生物多样性探索站的框架，明确测试（1）土地利用和土地利用相关的生物多样性对物种特异性PSFs的影响直接在外地。(2)通过设置不同土地利用强度下的植物竞争与土壤多样性联合试验，并在完全析因设计中明确排除地上和地下食草动物，我们将提供额外的机制解决方案，关于土地利用相关的土壤微生物群落多样性以及地上和地下食草动物对PSF的强度和方向及其对植物的后果的影响-物种表现和植物群落多样性。在我们的实验方法中，我们将计划（3）在自然田间条件下研究非生物因素（如施肥或土壤压实）对PSF的单独影响。由于土地利用强度影响植物多样性，由于植物多样性在先前的田间实验中对植物生长产生正反馈效应，以及由于植物生长影响非生物和生物土壤性质，我们将在一系列温室实验中研究（4）土地利用相关土壤生物区系对沿着土地利用梯度的植物丰度的影响和重要性，通过实验测试75个MIPs（3个区域× 25个MIPs）的生物土壤遗产和PSF效应，筛选大量的常见植物物种。这些数据将产生关于土地利用相关土壤生物区系对植物物种丰度和群落组成的贡献的重要信息，并将为其他土壤生物区系和植物相关群体（例如，为进一步研究选择物种）。通过我们的实验，我们希望能为植物物种共存机制的研究做出实质性贡献。

Results from our previous greenhouse experiments using soil communities from the Biodiversity Exploratories indicate that soil-biota effects along a land-use intensity gradient contribute to species coexistence by influencing plant-species dominance in grassland communities. Land-use related soil-biota effects in our experiments differed especially between grasses and herbs, suggesting a biotic legacy effect of land use on plant-community composition and coexistence in grasslands. However, when comparing plant-soil feedbacks (PSFs) under greenhouse and field conditions, we detected in a recent series of experiments consistent differences between PSF effects. In the field, we observed a generally positive effect of plant diversity on biotic feedbacks. This underlines the importance to consider land-use related diversity effects as plant diversity might drive indirect and intransitive competitive effects in natural vegetation. Previous results from the Biodiversity Exploratories clearly show that land-use intensity affects the diversity across trophic levels (plants, herbivores, pathogens). Therefore, we would like to use the framework of the Biodiversity Exploratories to explicitly test (1) the impact of land-use and land-use related biodiversity on species specific PSFs directly in the field. (2) By setting up a combined plant competition and soil diversity experiment at the different land-use intensities and by explicitly excluding above-and belowground herbivores in a fully factorial design, we will provide additional mechanistic resolution regarding the impact of land-use-related diversity of soil microbial communities as well as of above and belowground herbivores on the strength and direction of PSFs and their consequences for plant-species performance and thus plant-community diversity. Within our experimental approach, we will plan (3) to investigate the individual effects of abiotic factors such as fertilization or soil compactions on PSFs under natural field conditions.As land-use intensity affects the diversity of plants, as the diversity of plants resulted in positive feedback effects on plant growth in a previous field experiment, and as plant growth affects abiotic and biotic soil properties, we will investigate in a series of greenhouse experiments (4) the effect and importance of land-use related soil biota on plant abundance along the land-use gradient by experimentally testing biotic soil legacy and PSF effects of 75 MIPs (3 regions à 25 MIPs) in grasslands screening a large set of common plant species. These data will yield important information on the contribution of land-use related soil biota on plant species abundance and community composition, and will be provide substantial information for other soil biota and plant related groups (e.g., for species selection for further studies). With our experiments we hopefully substantially contribute to the study of mechanisms enabling plant-species coexistence.