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

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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.