Global change effects on forest understorey: how do interactions between drought and land-use intensity affect water, carbon and nitrogen cycling?

气候变化预计将严重影响整个中欧的降水模式。尽管地下森林在自然更新和森林演替中发挥着重要作用，但尚未对气候变化进行广泛的调查。我们建议在所有三个探索区建立林地屋顶系统，并研究对降水减少的响应的生物地球化学和水文过程，以及它们与林地利用类型、森林林下层和土壤生物群的多样性的相互作用。我们的研究集中在干旱对森林林下系统不同部分的直接和间接影响以及对植物生长的影响。我们将在跨越土地利用和生物多样性梯度的操纵实验中，研究土壤水文结构和功能以及降水状况对植物物种水和碳平衡的影响以及由此产生的群落效应。我们还将考虑干旱和植物多样性对微生物群落结构和功能的直接影响，并解决对土壤结构的生物反馈，从而解决水文功能。该项目将包括五个工作包(WPS)，其中三个计划立即开始，另外两个WPS将在3年后开始。第一阶段的三个WPS将涵盖植物个体和草本层植物群落和植被变化(WP1)、干旱对土壤结构的影响(WP2)和植物功能/微生物群落结构与土壤水文性质之间的相互作用(WP3)。工作包四和五对植物生根模式、养分吸收的较长期变化以及生态系统影响的数据感兴趣，以建立和验证生态系统模型。

Climate change is predicted to severely affect precipitation patterns across central Europe. The forest un-derstorey has not been subject to an extensive investigation with respect to climate change, yet, even though it is playing an important role in natural regeneration and forest succession. We propose here to es-tablish roof systems in forest plots in all three Exploratories and to study biogeochemical and hydropedologi-cal processes in response to reduced precipitation, and their interaction with forest land use type and the diversity of the forest understorey and of soil biota. Our research is focused on the direct and indirect effects of drought on different parts of the forest understorey system and the consequences for plant growth. We will address the effects of soil hydrological structures and functions and precipitation regime on the water and carbon balance of plant species and the resulting community effects in the manipulation experiments across land-use and biodiversity gradients. We will also take into account direct drought plus plant diversity effects on the microbial community structure and function and address the biotic feedback on soil structure and thus hydrological functions. The project will consist of five work packages (WPs), three of which are planned to start immediately, and the other two WPs to start after 3 years. The three WPs in the first phase will cover responses to drought at the level of individual plants and the herb layer plant community and vegetation change (WP1), drought effects on soil structure (WP2) and the interaction between plant function-ing/microbial community structure and soil hydrological properties (WP3). Work packages four and five are interested in longer-term changes of plant rooting patterns, nutrient uptake and in data on ecosystem effects to construct and validate ecosystem models.