DroughtNet: Establishing the International Drought Experiment at Cedar Creek sIDE (savanna IDE) : Percent Cover

Abstract: Droughts are forecast to become increasingly frequent and intense in many regions worldwide, likely impacting community structure, ecosystem functioning, and ecosystem services. The International Drought Experiment (IDE) is a coordinated, multi-site drought experiment requiring only a moderate investment of time and resources by investigators. This coordinated, distributed experiment will quantify the impacts of extreme drought across a wide range of terrestrial ecosystems based on a common experimental design and a comparable suite of measurements. We aim to establish two stand-alone experiments following the IDE design at Cedar Creek. Precipitation reduction shelters will be established during spring 2017 to simulate a 1 in 100 year dry event, which at our site corresponds to removing 43% of annual precipitation. The sIDE (savanna IDE) study will be established in Field D, an oak savanna, and will consist of 3 precipitation treatments (precipitation reduction shelter, inverted shelter as an infrastructure control, no shelter), fully crossed with two fertilization treatments (unamended control or NutNet NPK treatment), and with 5 replicate plots for each of the six treatment combinations, for a total of 30 plots, each 3 by 3 m (2 by 2 m inner area sampled), covered by 3 by 3 m shelters. The three precipitation treatments described above will be applied at the subplot level and fully crossed with the two current irrigation treatments (ambient or ambient plus ~2 cm per week of irrigation) and with two of the current fertilization treatments (unamended or 14 g N m-2), with six true replicate plots for each of the 12 treatment combinations, for a total of 72 subplots. Standard measurements across these two experiments and all other DroughtNet sites will include peak aboveground biomass clipping, soil carbon and nitrogen content, plant community composition from % cover, plant traits, and meteorological measurements (daily precipitation, air temperature). Many