Evaporation and transpiration from multiple proximal forests and wetlands

Authors: SHVEYTSER, VICTORIA - University Of Wisconsin; STOY, PAUL - University Of Wisconsin; BUTTERWORTH, BRIAN - University Of Wisconsin; WIESNER, SUSANNE - University Of Wisconsin; Skaggs, Todd; MURPHY, BAILEY - University Of Wisconsin; WUTZLER, THOMAS - Max Planck Institute For Biogeochemistry; EL-MADANY, TAREK - Max Planck Institute For Biogeochemistry; DESAI, ANKUR - University Of Wisconsin

Submitted to: Water Resources Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/9/2023
Publication Date: 1/25/2024
Citation: Shveytser, V., Stoy, P.C., Butterworth, B., Wiesner, S., Skaggs, T.H., Murphy, B., Wutzler, T., El-Madany, T.S., Desai, A.R. 2024. Evaporation and transpiration from multiple proximal forests and wetlands. Water Resources Research. 60(1). Article e2022WR033757. https://doi.org/10.1029/2022WR033757.
DOI: https://doi.org/10.1029/2022WR033757

Interpretive Summary: Global change is intensifying the hydrologic cycle and altering ecosystem function, including evapotranspiration (ET). ET is the sum of evaporation (E) and transpiration (T), which are impacted by global change in different ways. T is fundamental to understanding plant water stress, and both E and T are critical for understanding how ecosystems regulate water use. However, E and T are difficult to measure independently, especially across sites that represent different land use and land management strategies. This study quantified E and T across 12 different ecosystems in northern Wisconsin, USA. The study sites included 7 deciduous forests, 3 coniferous forests, and 2 wetlands. Average T/ET for the study period was 54.5% in forested sites and 46% in wetlands. Deciduous and coniferous forests showed similar E trajectories over time despite differences in vegetation phenology. E increased dramatically after large precipitation events in loam soils, consistent with the notion that lower infiltration rates temporarily enhance E. The research will assist scientists in understanding the way climate change is affecting ecosystem function.

Technical Abstract: Global change is intensifying the hydrologic cycle and altering ecosystem function, including evapotranspiration (ET). ET is made up of evaporation (E) via non-stomatal surfaces and transpiration (T) through plant stomata, which are impacted by global changes in different ways. Plants respond to water scarcity by closing stomata, which decreases T and evaporative cooling, increasing leaf surface temperature and decreasing carbon uptake to which the water cycle is coupled. T is fundamental to understanding plant water stress, and both E and T are critical for understanding how ecosystems regulate water use. However, E and T are difficult to measure independently, especially across sites that represent different land use and land management strategies. To address this gap in understanding, we applied flux variance similarity to quantify how E and T differ across 12 different ecosystems measured using eddy covariance in a 10 × 10 km area from the CHEESEHEAD19 experiment in northern Wisconsin, USA. The study sites included 7 deciduous forests, 3 coniferous forests, and 2 wetlands. Net radiation explained on average 68% of the variance of T, which decreased from summer to autumn. Average T/ET for the study period was 54.5% in forested sites and 46% in wetlands. Deciduous and coniferous forests showed similar E trajectories over time despite differences in vegetation phenology. E increased dramatically after large precipitation events in loam soils, consistent with the notion that lower infiltration rates temporarily enhance E. Results suggest that E and T partitioning methods are promising for comparing ecosystem hydrology across multiple sites.