Abstract
Climate change is intensifying the hydrologic cycle and altering ecosystem function, including water flux to the atmosphere through 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. E and T are difficult to measure independently at the ecosystem scale, especially across multiple sites that represent different land use and land management strategies. To address this gap in understanding, we applied flux variance similarity (FVS) to quantify how E and T differ across 13 different ecosystems measured using eddy covariance in a 10 × 10 km area from the CHEESEHEAD19 experiment in northern Wisconsin, USA. The study sites included eight forests with a large deciduous broadleaf component, three evergreen needleleaf forests, and two wetlands. Average T/ET for the study period averaged nearly 52% in forested sites and 45% in wetlands, with larger values after excluding periods following rain events when evaporation from canopy interception may be expected. A dominance analysis revealed that environmental variables explained on average 69% of the variance of half-hourly T, which decreased from summer to autumn. Deciduous and evergreen forests showed similar E trajectories over time despite differences in vegetation phenology, and vapor pressure deficit explained some 13% of the variance E in wetlands but only 5% or less in forests. Retrieval of E and T within a dense network of flux towers lends confidence that FVS is a promising approach for comparing ecosystem hydrology across multiple sites to improve our process-based understanding of ecosystem water fluxes.
| Original language | English |
|---|---|
| Article number | e2022WR033757 |
| Journal | Water Resources Research |
| Volume | 60 |
| Issue number | 1 |
| DOIs | |
| State | Published - Jan 2024 |
| Externally published | Yes |
Funding
CHEESEHEAD19 was primarily supported from the National Science Foundation Award 1822420 in addition to support from the DOE Ameriflux Network Management Project and NOAA. Brian Butterworth was additionally supported by the NOAA Physical Sciences Laboratory. NOAASURFRAD measurements were provided by NOAA's Climate Program Office, Climate Observations and Monitoring Program Project NA20OAR4310338. We thank NCAR's Earth Observing Laboratory, sponsored by the National Science Foundation for their operational, technical, and scientific support. We thank Anita Thompson for insightful comments on the manuscript. This project would not be possible without the support provided by the U.S. Forest Service and Wisconsin Educational Communications Board. We wish to acknowledge the Indigenous Nations on whose ancestral lands and ceded territories the study took place and recognize that the infrastructure used for this project is built on Indigenous land. We recognize the Ojibwe people as past, present, and future caretakers of this land whose stewardship of the region was interrupted through their physical removal by the 1830 Indian Removal Act and through US Assimilation policies explicitly designed to eradicate Indigenous language and ways of being until the 1970s. CHEESEHEAD19 was primarily supported from the National Science Foundation Award 1822420 in addition to support from the DOE Ameriflux Network Management Project and NOAA. Brian Butterworth was additionally supported by the NOAA Physical Sciences Laboratory. NOAASURFRAD measurements were provided by NOAA's Climate Program Office, Climate Observations and Monitoring Program Project NA20OAR4310338. We thank NCAR's Earth Observing Laboratory, sponsored by the National Science Foundation for their operational, technical, and scientific support. We thank Anita Thompson for insightful comments on the manuscript. This project would not be possible without the support provided by the U.S. Forest Service and Wisconsin Educational Communications Board. We wish to acknowledge the Indigenous Nations on whose ancestral lands and ceded territories the study took place and recognize that the infrastructure used for this project is built on Indigenous land. We recognize the Ojibwe people as past, present, and future caretakers of this land whose stewardship of the region was interrupted through their physical removal by the 1830 Indian Removal Act and through US Assimilation policies explicitly designed to eradicate Indigenous language and ways of being until the 1970s.
Keywords
- evaporation
- evapotranspiration
- forest
- soil
- transpiration
- wetland
