Temporal dynamics of tree diversity effects on growth, mortality and biomass production (BIOTREE project)

生物多样性日益被认为是直接影响许多生态过程和功能的生态系统的关键组成部分。生物多样性-生态系统功能研究的最大部分仍然来自快速增长的小型模型系统，如草原。然而，最近科学家们开始研究复杂木本系统中树木多样性变化的影响。在这样做的过程中，在过去的20年里建立了几个树木多样性实验，现在形成了一个这样的实验的全球网络。在这里，我建议在位于德国图林根州的一些最古老的树木多样性实验（BIOTREE）中分析树木多样性对生长、死亡率和生物量产生的意义。BIOTREE项目包括在三个地点进行的四个不同的实验，在这些地点种植了不同树木多样性的新树木，采用了不同的设计。在两个实验中，建立了树种丰富度的梯度。在第三个实验中，在保持每个地块物种数量不变的情况下，创造了功能多样性的差异。在第四项试验中，对物种均匀度和种植密度进行了控制。总共种植了20多万棵树。我建议延长现有的树木生长和死亡率评估时间序列，在种植后16年进行新的测量活动。中心目标是调查和量化树木多样性对树木生长、死亡率和生物量生产的时间尺度依赖性。此外，基于无人机的树木高度测量将在密集的树木中进行测试。该项目将首次提供树木多样性-生产力关系的长期数据，从而为森林生物多样性-生态系统功能研究做出贡献。

Biodiversity is increasingly recognized as a key component of ecosystems that directly influences many ecological processes and functions. The largest fraction of biodiversity-ecosystem functioning research still comes from fast-growing and small-statured model systems such as grasslands. However, more recently scientists have started to study the effects of changing tree diversity in complex woody systems. In doing so, several tree diversity experiments have been established within the last 20 years, forming now a global network of such experiments. Here, I propose to analyse the significance of tree diversity for growth, mortality and biomass production in some of the oldest tree diversity experiments (BIOTREE), located in Thuringia, Germany. The BIOTREE project encompasses four different experiments at three sites, where new tree stands differing in tree diversity have been planted adopting different designs. In two experiments, gradients of tree species richness have been established. In a third experiment, differences in functional diversity have been created while keeping the number of species per plot constant. In a fourth experiment, species evenness and planting density have been manipulated. In total, more than 200,000 trees have been planted. I suggest to extend existing time series of tree growth and mortality assessments with a new measurement campaign 16 years after planting. The central aim is to investigate and quantify temporal scale dependencies of tree diversity effects on tree growth, mortality and biomass production. In addition, drone-based tree height measurements will be tested for the use in dense tree stands. This project will provide first long-term data on the tree diversity-productivity relationship, thus contributing to forest biodiversity-ecosystem functioning research.