We study past, present, and future global change and its impacts on Earth’s ecosystems
We use remote sensing, dendrochronology (the science of tree rings) and dendrometers, eddy covariance, and empirical/process-based modeling to understand how our climate has changed, how ecosystem structure and function (especially in forests and drylands) have responded to those changes, and how vegetation will influence future change. Much of our work specifically investigates how changes in the water cycle -- especially increases in precipitation variability and vapor pressure deficit -- affect the growth, phenology, carbon cycling, and water use of terrestrial vegetation. Our research spans regional to global spatial scales and fast (minutes to days) to slow (decades to centuries) time scales.
Current projects
Tree growth legacies of soil & atmospheric drought across climatic, plant trait, and morphological gradients
We are examining the combined effects of "soil drought" (low soil moisture) and "atmospheric drought" (high vapor pressure deficit) on growth of U.S. forests and how that response depends on aridity, species traits, and tree size. Funded by U.S. Dept. of Energy, 2024-2026. ECH2O personnel: Matt Dannenberg, Qing Chang
Reducing uncertainties in tree-ring records of wet extremes
Using tree-ring widths, dendrometers, and process-based models, we are examining responses of U.S. tree growth to extreme precipitation, with the goal of understanding how wet extremes get "encoded" in the tree-ring record and how changes in precipitation extremes will affect forest growth. Funded by U.S. National Science Foundation, 2024-2027. ECH2O personnel: Matt Dannenberg, Feng Wang
Acquiring plant growth chambers for research and teaching in ecology and plant science
In collaboration with the LOQATE Lab, we obtained eight Percival E-41L2 plant growth chambers for use in global change experiments on potted plants to support research and teaching at University of Iowa. Funded by the Roy J. Carver Charitable Trust, 2024-2025. ECH2O personnel: Matt Dannenberg, Xiuchen Jiang
Past projects
Multi-Century Perspectives on Current and Future Flow in the Lower Missouri River Basin
We used new and existing tree-ring collections to reconstruct streamflow in the Lower Missouri River Basin and to understand its hydroclimatic drivers. Funded by U.S. National Science Foundation, 2020-2024. ECH2O personnel: Matt Dannenberg, Victoria Harris
Leveraging SMAP and MODIS to quantify variability and drivers of dryland carbon and water fluxes
We developed global estimates of dryland gross primary production and evapotranspiration using SMAP soil moisture with MODIS surface reflectance and land surface temperature, and we examined responses of those carbon and water fluxes to hydroclimatic extremes. Funded by NASA, 2020-2024. ECH2O personnel: Matt Dannenberg, Miriam Johnston, Qing Chang
Amplification of drought effects on vegetation by anthropogenic warming
We quantified the extent to which anthropogenic warming increased the impacts of drought on primary production during the 21st century western U.S. megadrought. Funded by U.S. National Science Foundation, 2022-2024. ECH2O personnel: Matt Dannenberg, Miriam Johnston