COS 112-9
Integrating multiscale data from satellite- and ground-based sensors to assess climate-driven changes in ecological conditions on wetland-upland landscapes
Landscapes of interconnected wetlands and uplands provide multiple ecosystem services vital to humans and are essential for wetland-dependent biota, such as amphibians, populations of which have declined worldwide. Climate-driven changes in temperature and precipitation regimes threaten to alter ecological conditions and relations across these landscapes in ways not well understood. Yet, the long-term integrated assessments that are necessary to understand the nature and severity of any climate-induced changes in key landscape conditions have been lacking, especially across spatial scales. We initiated such an assessment in 2008 as part of the Terrestrial Wetland Global Change Research Network to address questions regarding if and how conditions have changed recently and how they might change in the future. We report initial results from 2008–2012 for four network research areas in Minnesota and Wisconsin, USA, based upon data collected via sensors on MODIS and Landsat satellites, regional weather stations, and water-depth loggers and acoustic recorders deployed at individual wetlands. We analyzed snow cover, temperature, precipitation, primary productivity, and evapotranspiration for 35 local (4-km2) landscapes, where we also measured water depth and amphibian calling activity and modeled site occupancy for individual wetlands. We then compared relations among variables within and across years.
Results/Conclusions
Weather-station data showed March of 2012 was the warmest on record dating back to 1895 and March of 2010 was the fourth warmest, whereas 2008, 2009, and 2011 were closer to the median. Amphibians began calling each year in accordance with these weather dynamics, but only when the weekly mean daily temperature was ≥ 0⁰ and almost always after snow had melted. Wetland water depth varied markedly by site and year and was associated with total weekly precipitation at a majority of sites. Amphibian calling activity typically was associated with water depth when depth waxed and waned within a season, but not when it declined gradually. Site occupancy for Pseudacris crucifer, a common, short-lived amphibian species was high and did not differ across years. Limited precipitation resulted in wetlands drying and no amphibian reproduction at some sites in some years. Photosynthetic activity and evapotranspiration, derived from satellite data for local landscapes, changed similarly in response to weather, but understanding these changes required analyzing the interplay of temperature with precipitation throughout the season. Our initial results demonstrate substantial annual and interannual variation in ecological conditions, climate-driven relations among most variables we measured, and the potential effectiveness of our integrated, long-term approach.