Understorey plant assemblages and primary production

林下植物群落和依赖木材的苔藓植物和地衣是温带森林多样性的主要组成部分，在初级生产力、小气候调节、分解或生境供应等多种生态系统功能中发挥着重要作用。大量证据表明，这些分类群对生境条件的时空变化响应强烈，导致群落组成和多样性在局部（α-多样性）尺度上发生变化。因此，通过提高斑块（ESC处理）和区域（即景观）水平（ESBC处理）的结构复杂性来改变生物和非生物环境，预计将对这些物种组合和相关生态系统过程产生重要的功能影响。然而，ESBC对真实森林景观中林下植物群落和木材依赖性隐生植物的分类和功能β-多样性的影响方向和程度尚不清楚。本子项目的主要目的是调查通过ESBC处理的温带森林的更高空间异质性在多大程度上增加了非树维管植物、陆生苔藓植物和地衣在林下植被以及依赖木材的苔藓植物和地衣的β多样性。在非树维管植物的情况下，我们进一步打算分析这如何反馈到它们在生物量生产力方面的地上和地下功能。我们将对所有斑块的林下植被和依赖木材的苔藓植物和地衣进行取样。这使我们能够延长2016年至2018年期间在esbc处理地区开始的时间序列。为了计算α-和β-尺度上的功能多样性指标，我们将测量非树维管植物的叶、根和植株大小相关的功能性状。此外，还将测定林下植被的地上和地下生物量，以估计生产力。我们将验证ESBC处理导致的空间异质性增加将增强林下非树维管植物、陆生苔藓植物和地衣的分类和（全株）功能β-多样性（假设1），以及分类和功能β-多样性的增加对林下植物群落的地上和地下生产力产生积极影响（假设2）。对于整个研究单元，我们将提供维管植物、陆生植物以及依赖木材的苔藓植物和地衣的生物多样性数据。此外，我们将测量非树维管植物的性状，以添加到性状数据库中。我们的子项目将确定下层主要的地上和地下生产力作为重要的生态系统功能，有助于多功能分析。

Understorey plant communities and wood-dependent bryophytes and lichens are major components of temperate forest diversity and play an essential role for multiple ecosystem functions such as primary productivity, microclimate regulation, decomposition or habitat provisioning. There is much evidence that these taxa strongly respond to changes in habitat conditions across spatial and temporal scales, leading to shifts in community composition and diversity at the local (α-diversity) scale. Thus, modifications of the biotic and abiotic environment by enhancing structural complexity at the patch (ESC treatments) and district (i.e. landscape) level (ESBC treatments) are expected to have important functional consequences for these species assemblages and related ecosystem processes. However, the direction and magnitude of ESBC effects on taxonomic and functional β-diversity of understorey plant communities and wood-dependent cryptogams in real forest landscapes still remains unclear. The main objective of this subproject is to investigate to which extent a higher spatial heterogeneity of temperate forests via ESBC treatments increases the β-diversity of non-tree vascular plants, terricolous bryophytes, and lichens in the understorey vegetation as well as of wood-dependent bryophytes and lichens. In the case of non-tree vascular plants we furthermore intend to analyse how this feedbacks to their above- and belowground functioning in terms of biomass productivity. We will sample the understorey vegetation and wood-dependent bryophytes and lichens in all patches. This allows us to extend a time series which has been started in the ESBC-treated districts during the years 2016 to 2018. Leaf, root and plant size-related functional traits of non-tree vascular plants will be measured in order to calculate functional diversity metrics at α- and β-scales. In addition above- and belowground biomass of the understorey vegetation will be determined to estimate productivity. We will test the hypotheses that the increase in spatial heterogeneity caused by ESBC treatments will enhance the taxonomic and (whole-plant) functional β-diversity of non-tree vascular plants, terricolous bryophytes, and lichens found in the forest understorey (Hypothesis 1) and that the increase in taxonomic and functional β-diversity positively affects the aboveground and belowground productivity of understorey plant communities at the district level (Hypothesis 2). For the whole research unit we will provide biodiversity data for vascular plants, terricolous as well as wood-dependent bryophytes and lichens. Additionally, we will measure traits of non-tree vascular plants to be added to the trait database. Our subproject will determine understorey primary aboveground and belowground productivity as an important ecosystem function, contributing to the multifunctionality analysis.