Land-use effects on longevity and stem anatomical traits of perennial dicotyledonous species in grasslands

寿命是一个重要的人口统计学特征，对植物物种的生活史、植物种群的持久性和稳定性以及植物物种对环境变化的响应具有重要意义。关于植物个体（或品种）的寿命，特别是其随土地利用和地理区域的变化的信息，在许多常见的草地物种中是没有的。此外，在草本物种的生态学研究中，与运输、储存和机械支撑等功能相关的茎解剖性状在很大程度上被忽视，因此不知道这些性状对环境条件变化的反应有多敏感。本项目的主要目的是通过使用生长年轮来研究植物个体（或品种）的寿命，并通过测量生物多样性实验区草原上大量多年生双子叶草本植物的茎解剖特征来解决这一知识的缺乏。主要研究目标如下：(1)测定各试验区150个实验草地中最丰富的多年生双子叶草本植物物种的寿命，研究其与不同草地的土地利用和物种多样性之间的关系，以及不同环境条件下区域间的差异。(2)研究4种多年生常见双子叶草本植物种群的寿命谱和分布，探讨年龄结构与种群规模和稳定性的关系如何因土地利用、物种多样性和区域环境差异而变化。(3)对所有样本的生长环宽度和茎解剖性状进行分析，以评估其对植物个体（或株）年龄、土地利用和草原多样性或区域间环境差异的依赖性。(4)大量多年生双子叶草本植物的寿命和茎解剖特征数据将与系统发育和生长繁殖相关性状相关，以检验性状之间的权衡。该项目将首次确定大量多年生双子叶草本植物的单株（或分株）寿命和茎解剖特征的变化与草原土地利用、物种多样性和区域环境差异的关系。我们将把基于性状的生态学扩展到人口统计学的角度，这是理解植物种群的生存能力和持久性以及植物群落的长期稳定性的重要前提。

Life span is a key demographic trait important for the life history of plant species, the persistence and stability of plant populations and plant species` responses to environmental changes. Information on the longevity of plant individuals (or ramets) and specifically its variation dependent on land use and geographic regions is not available for a large number of common grassland species. Moreover, stem anatomical traits related to functions such as transport, storage and mechanical support are largely ignored in ecological studies of herbaceous species and therefore it is not known how sensitively these traits respond to variation in environmental conditions. This project has the major aim to address this lack of knowledge by using growth rings to study the longevity of plant individuals (or ramets) and by measuring stem anatomical characteristics for a large number of perennial dicotyledonous herb species in the grasslands of the Biodiversity Exploratories. The following main objectives will be addressed: (1) Longevity of the most abundant perennial dicotyledonous herb species in each of the 150 experimental grassland plots of the Exploratories will be determined to test how it is related to land use and species diversity of different grasslands or varies among regions with different environmental conditions. (2) The spectrum and distribution of life spans in populations of four frequent perennial dicotyledonous herb species will be studied to test how the relationship between age structure and population sizes and stabilities varies dependent on land use, species diversity and environmental differences between regions. (3) Growth ring width and stem anatomical traits will be analyzed in all samples to assess their dependency on age of the plant individuals (or ramets), land use and diversity of grasslands or environmental differences between regions. (4) Data on life span and stem anatomical characteristics of a large number of perennial dicotyledonous herb species will be related to phylogeny and traits related to growth and reproduction to test for trade-offs between traits. This project will be novel in determining for the first time for a large number of perennial dicotyledonous herb species how variation in plant individual (or ramet) longevity and stem anatomical characteristics is related to land use, species diversity and regional environmental differences in grasslands. We will extend trait-based ecology to a demographic perspective which is an important prerequisite to understand the viability and persistence of plant populations and the long-term stability of plant communities.