LTREB Renewal: Streams to Screens: Bringing the Hubbard Brook Watershed Ecosystem Record (HBWatER) into the 21st Century

This project seeks to understand how water and chemical elements move through ecosystems, and how these processes respond to environmental change. It continues a globally unique 60-year record of precipitation and stream chemistry for ten streams in the Hubbard Brook Experimental Forest in the White Mountains of New Hampshire. This record shows the impacts of air pollution, climate change, and pests on forests, soils, and streams. It has been essential for recording the effects of pollution control laws and for developing and testing theories about how forested ecosystems work. The project will examine how these ecosystems are recovering from acid deposition, as well as how they are responding to new impacts, such as a changing climate. Data from the project are publicly available, and additional broader impacts include the training of undergraduate students through a summer REU. The project measures the chemistry of weekly precipitation and streamwater samples. Some of these watersheds have been subjected to whole-watershed manipulations such as experimental tree harvest, and all of the watersheds are experiencing long-term changes in acid deposition and climate. Chemical analyses include pH, conductivity, dissolved organic and inorganic carbon, major anions and cations, dissolved silica, and trace elements, among other measurements. Input and export fluxes of chemical elements are calculated for nine of the watersheds using precipitation and stream discharge data. The study design uses long-term observation of chemical fluxes through these ecosystems to test and refine theory about ecosystem processes and their responses to change. Key questions to be tested include, among others: 1) The effects of forest disturbance on nutrient losses from soils, and how this interacts with recovery from acidification; 2) How climate change and long-term decreases in stream solute concentrations will interact to control the timing, magnitude, and form of watershed exports; and 3) The long-term effects of forest disturbance on stream pH and the export of dissolved organic carbon and weathering products. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.