Project

community assembly; ecosystem functioning; biodiversity; evolution; plant ecology; biodiversity effect; combining ability; grassland community; plant-soil feedback; home-away effect; soil community; soil pathogens; community history; Evolution, Grassland community

Lead
Lay summary
It is conceivable that specific interaction networks among species develop over time in natural plant communities, making them more productive and more stable than newly assembled communities. The aim of this project is to test if such effects of community history can be detected after 8 years in experimental grassland communities of the "Jena Experiment", a large biodiversity research platform in Germany.In a fist subproject we will test if selection for increased combining ability occurs if different species are growing together in mixed communities for a prolonged time. We will compare this selection regime providing a common community history with the results of selection of the two species in separate monocultures. In addition, we expect that newly established mixed communities will have higher yield if they contain plants that have been selected in mixtures rather than monocultures. If the tests were positive, it would suggest that 8 years of differential survival and reproduction in mixtures vs. monocultures can select for genotypes with high vs. low interspecific combining abilities.In a second subproject we will re-assemble the same experimental communities as established 8 years ago on the original plots of the Jena Experiment with plants taken from the 8-year old communities of the same plot (common plant history) or from the supplier which provided the original seeds in 2001 and with unsterilized (common soil history) or sterilized soil taken from the same plots. Here the prediction is that biodiversity effects based on complementary resource use and interactions with soil organisms will be stronger in re-assembled communities with common history. These communities should also be more stable temporally (in terms of invasibility, species abundances) than those without common history.Measurements will focus on plant individuals and communities (survival, growth, morphology, reproduction, biomass); soil abiotic and biotic variables will be assessed in collaboration with other groups. Data will be analyzed with general linear models and mixed-model analysis of variance. The proposed research should contribute to the basic questions of how tightly integrated plant communities are and whether integration increases during community development (evolution of combining ability, plant-soil community assembly processes). A better understanding of these questions is essential because they are related to the management of biodiversity and ecosystem functioning.

Direct link to Lay Summary

Last update: 21.02.2013

Number	Title	Start	Funding scheme

Biodiversity experiments have shown that the functioning of ecosystems can be reduced if species are lost from the system. For example, productivity and stability of plant communities generally increase with plant species richness in such experiments. What remains unclear is how well the experimental communities represent natural communities. It is conceivable that specific interaction networks among species develop over time in natural communities, making these communities more productive and more stable than newly assembled experimental communities of similar species richness. I would like to test if such developments already occurred over a time-span of 8 years in the Jena Experiment, a large biodiversity research platform in Germany.My hypotheses are that evolutionary (Project A) and ecological (Project B) processes can lead to changed interactions between plant species in communities of different species richness and composition. In Project A we will test whether seed offspring of populations of two species which grew for 8 years together in mixture (common community history) will have increased performance when again grown in mixture (= interspecific combining ability) compared with the case where each of the two species grew for 8 years in monoculture (or with different species in mixture). In addition, we will test if four-species mixtures have lower performance if established with seeds taken from 8-year old monocultures rather than mixtures. If the tests were positive, it would suggest that 8 years of differential survival and reproduction in mixtures vs. monocultures can select for genotypes with high vs. low interspecific combining abilities.In Project B we will re-assemble the same experimental communities as established 8 years ago on the original plots of the Jena Experiment with plants taken from the 8-year old communities of the same plot (common plant history) or from the supplier which provided the original seeds in 2001 and with unsterilized (common soil history) or sterilized soil taken from the same plots. All soil will receive a standard microbial inoculum and left unplanted during winter to leach out nutrients that appeared during sterilization. Here the prediction is that biodiversity effects based on complementary resource use and interactions with soil organisms will be stronger in re-assembled communities with common history. These communities should also be more stable temporally (in terms of invasibility, species abundances) than those without common history.Experiments will be carried out at the field site in Jena and in the experimental garden and glasshouse of the Institute of Environmental Sciences in Zurich. Measurements will focus on plant individuals and communities (survival, growth, morphology, reproduction, biomass); soil abiotic and biotic variables will be assessed in collaboration with other groups. Data will be analyzed with general linear models and mixed-model analysis of variance.The proposed research should contribute to the basic questions of how tightly integrated plant communities are (e.g. neutral vs. niche structured) and whether integration increases during community development (evolution of combining ability, plant-soil community assembly processes). A better understanding of these questions is essential because they are related to the management of biodiversity and ecosystem functioning.