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Temporal trends in effects of global change on plant communitiesGlobal change drivers (GCD) such as nitrogen deposition, elevated CO2 and temperatures are affecting plant communities over short timescales. But how GCDs may influence plant communities under prolonged exposure, similar to conditions under ongoing climate change, are relatively less studied due to the limited number of long-term studies. To address this, we leverage data from one such long-term experiment, BioCON, which manipulates diversity, CO2 and N levels to study a) how responses of different functional groups to GCDs change over a 25 year period; b) whether multiple GCDs have a synergistic or antagonistic effects on diversity and functional traits; and c) examine temporal trends in Biodiversity Ecosystem Function relationships.
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Intraspecific variation in plant defense traitsWithin species variation in defense traits is poorly characterized for plants adapted to intense large mammal herbivory, especially in the context of multiple resource gradients. We studied intraspecific variation for several traits in natural populations of Solanum incanum, and found that rainfall and P supply are strongly associated with physical defense traits. Additionally, multiple traits showed unexpected covariation leading us to propose a new hypothesis for integrating defense and leaf economic spectrum traits.
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Multiple resource influence on plant-herbivore interactionsPlants are simultaneously limited by the availability of multiple resources, but its implications for resource-plant-herbivore interactions are less well understood. Therefore, we developed an analytical model to provide testable hypotheses for responses of herbivores along gradients of different types of resources. The model predicts indirect limitation of herbivores by resources that do not limit their growth (such as phosphorus) which may allow these non-limiting resources to act as "resource subsidies". We tested some of the predictions using data from a long term grazing exclosure study in the Serengeti National Park and found that herbivore impacts on plants are indeed positively associated with P supply in the system.
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