Consequences of more extreme precipitation regimes interacting with land use practices for productivity and diversity of temperate grassland
Extreme precipitation and land use
From 01/2010 to 12/2012Extreme weather events are expected to increase in frequency and magnitude due to climate change. Additionally, greater intra-annual rainfall variability is predicted for many regions on earth. Their effects on vegetation and ecosystem functions are widely unknown. However, extremes in drought or precipitation events receive growing attention from the scientific community. First evidence suggests that extreme weather events alter i.e. plant productivity, carbon allocation, and competition between plant species, flower phenology and invasibility of plant communities. These findings have ecological and agricultural implications. Yet, effects of land use interacting with greater intra-annual rainfall variability and more extreme weather events have received minimal attention from the scientific community. Particularly, to our knowledge, experimental analyses of the potential of altered mowing and fertilization regimes to accelerate or mitigate effects of extreme weather events on ecosystem functions in temperate grassland have not been published to date. Within this project, we want to analyze the effects of four different precipitation regimes varying in distribution (frequency) and seasonality interacting with four different land use regimes varying in frequency and magnitude on productivity and diversity of natural grassland communities in Central Europe. Productivity is the most relevant ecosystem function and economic currency for agriculture, diversity the most fundamentally debated parameter in ecological theory and most widely used indicator of vegetation change in conservation management and policy. We assume that changes in the frequency and seasonality of precipitation events interacting with changes in land use practices will substantially alter plant productivity, vegetation composition, and species distributions. We will conduct a field experiment in natural grassland stands to analyze interacting effects between climate change and land use, simulating spring drought, summer drought, regular weekly average rainfall and ambient conditions. The manipulations of the precipitation regime will include the local 1000-year drought event according to extreme value statistics, or the 30 year weekly average respectively. These climate change scenarios will be realized in a factorial combination with two mowing regimes and two fertilizing regimes, imitating local agricultural practices. We are particularly interested in exploring the potential of land use to enhance or buffer effects of climate change on plants and ecosystem functions. We will address above and below ground biomass production and protein content of selected species and monitor relative species abundance and diversity of plant communities. Other colleagues will jointly study flower phenology, photosynthetic activity, root mycorrhization, insect herbivory, and flower pollination within the same experimental setting. Finally, we want to discuss implications for plant performance and plant distribution in cultural landscapes in the temperate zone in future climate.
Funded by: DFG JE 282/6-1