About
         

D. Scott Mackay

Professor
Department of Geography
University at Buffalo
105 Wilkeson Quadrangle
Buffalo, NY 14261 USA

Phone: +1-716-645-0477
Fax: +1-716-645-2329

dsmackay at buffalo dot edu

Curriculum vitae

Past Editor:
Water Resources Research
American Geophysical Union

AGU Ecohydrology Leaf



ORCID iD

Web of Science

ResearchGate

Google Scholar


Ecohydrology Group
Department of Geography
Department of Environment and Sustainability

How do plants thrive in stressful environments? As the world warms and some regions become drier there is pressing need for understanding the connections between hydrology and plant ecophysiology. Our interdisciplinary group sits at this nexus. We combine observations with hard to observe processes that are represented in simulation models. Our models simulate plant water transport, photosynthesis, and growth using physical equations and biological first principles. We use the models to reveal the emergent traits that underlie drought-induced tree mortality, enhanced or suppressed carbon cycling, and plant water demand.


Climate Dynamics and Tree Mortality

Nature Reviews - Cover Image
                                    Showing Dead TreeEnvironmental Researfh Letters
                                    - Cover Image Showing Dead TreeNew Phytologist - Cover Image
                                    Showing Forest Mortality

How will forests fare in a warming world? This is an urgent question because healthy forests are important carbon sinks, but when trees die they become a carbon source. Forests also transpire 40% of the global average precipitation falling on land areas, which makes forests integral to Earth's water cycle. Our research output titles include:

The influence of increasing atmospheric CO2, temperature, and vapor pressure deficit on seawater-induced tree mortality

Mechanisms of woody-plant mortality under rising drought, CO2, and vapor pressure deficit

Lateral subsurface flow modulates forest mortality risk to future climate and elevated CO2

Forecasting semi-arid biome shifts in the anthropocene

Multi-scale predictions of massive conifer mortality due to chronic temperature rise

Interdependence of chronic hydraulic dysfunction and canopy processes can improve integrated models of tree response to drought

Evaluating theories of drought-induced vegetation mortality using a multi-model-experiment framework


Belowground Processes Affecting Tree Survival

Representative of Belowground
                                  Processes in Models

The fate of trees is determined largely by the ability of their roots to access water. Scientists have long sought to overcome the inability to peer into the subsurface to see how root processes interact with other processes occurring below ground. We have developed a novel modeling approach that provides a "lens" for seeing below the surface. We ask how does root growth prior to and during drought allow trees to adjust their water uptake depths to access reliable water sources during drought? Here you can read about our findings so far:


Tree water uptake patterns across the globe

Stability of tropical forest tree carbon-water relations in a rainfall exclusion treatment through shifts in effective water uptake depth

Conifers depend on established roots during drought: results from a coupled model of carbon allocation and hydraulics

Mechanisms of a coniferous woodland persistence under drought and heat

Co-occurring woody species have diverse hydraulic strategies and mortality rates during an extreme drought


Hydrologic Controls Over Ecosystem Function

WRR issue cover - ParFlow-TREES
                                  cottonwood studyParFlow-TREES

Lateral subsurface flow and saturated soil zones play important roles in mediating tree health, but this hydrology has generally been neglected when considering the physiological responses of plants to drought. Our work explicitly addresses this gap by considering the integrated systems of plant hydraulics and groundwater hydrology. Here you can read about our findings so far:

Distributed plant hydraulic and hydrological modeling to understand the susceptibility of riparian woodland trees to drought-induced mortality

Lateral subsurface flow modulates forest mortality risk to future climate and elevated CO2

Dependence of aspen stands on a subsurface water subsidy: Implications for climate change impacts

Ecohydrological decoupling under changing disturbances and climate

Hillslope hydrology in global change research and Earth system modeling

Plant hydraulics improves and topography mediates prediction of aspen mortality in southwestern U.S.


Forest Disturbance

Bark Beetle Tree Mortality in
                                  Chimney Park, WyomingModeled evapotranspiration with
                                  cohorts of beelte attacked trees

Biotic and other disturbances combine with drought to exacerbate forest decline and consequent changes to water resources. These disturbances are an integral part of whole ecosystems responses. Here you can read about our findings so far:

Plant hydraulic stress explained tree mortality and tree size explained beetle attack in a mixed conifer forest

Mechanisms of a coniferous woodland persistence under drought and heat

Improving ecosystem-scale modeling of evapotranspiration using ecological mechanisms that account for compensatory responses following disturbance

Interannual consistency in canopy stomatal conductance control of leaf water potential across seven tree species


Hydraulic Constraints to Plant Growth

Improving Crop Growth
                                    Prediction Using Biophysical Process
                                    Models

Plant traits interact with environmental conditions to influence plant growth and productivity. By examining these interactions using crop species and biophysical process-based models, we are exploring mechanisms by manipulating both plant traits and environment. This enables us to use a robust hypothesis testing framework to study traits that are transferable to natural settings and novel environmental conditions. Here you can read about our findings so far:

Combining PSII photochemistry and hydraulics improves predictions of photosynthesis and water use from mild to lethal drought

Physiological trait networks enhance understanding of crop growth and water use in contrasting environments

Use of hydraulic traits for modeling genotype-specific acclimation in cotton under drought

Use of transcriptomic data to inform biophysical models via Bayesian networks

Rapid chlorophyll a fluorescence light response curves mechanistically inform photosynthesis modeling

A framework for genomics-informed ecophysiological modeling in plants


Evapotranspiration Spatial Dynamics

Northern Wisconsin
                                  Evapotranspiration StudyNorthern Wisconsin Spatial
                                  Transpiration Stidy

Evapotranspiration represents the largest path taken by precipitation once it falls on terrestrial systems, and it is mediated by plants. We have asked how species, plant age, disturbance, and gradients associated with edaphic, topographic, and micrometeorologic dynamics affect evapotranspiration, and how the associated mechanisms can be used to build robust yet simple models. A lot of our earlier work (early 2000s) provided the empirical and theoretical foundation for developing the Terrestrial Regional Ecosystem Exchange Simulator (TREES). Here you can read about our findings so far:

Ecohydrological decoupling under changing disturbances and climate

Model-data fusion approach to quantify evapotranspiration and net ecosystem exchange across the sagebrush ecosystem at different temporal resolutions

Improving ecosystem-scale modeling of evapotranspiration using ecological mechanisms that account for compensatory responses following disturbance

Bayesian analysis of canopy transpiration models: A test of posterior parameter means against measurements

Competition for light between individual trees lowers reference canopy stomatal conductance: results from a model

On the representativeness of plot size and location for scaling transpiration from trees to a stand

Contribution of competition for light to within-species variability in stomatal conductance

Tree transpiration varies spatially in response to atmospheric but not edaphic conditions

Using temporal patterns in vapor pressure deficit to explain spatial autocorrelation dynamics in tree transpiration

Environmental drivers of spatial variation in whole-tree transpiration in an aspen-dominated upland-to-wetland forest gradient

Intercomparison of Sugar Maple (Acer saccharum Marsh.) stand transpiration responses to environmental conditions from the Western Great Lakes Region of the United States

Environmental drivers of evapotranspiration in a shrub wetland and an upland forest in northern Wisconsin

Interannual consistency in canopy stomatal conductance control of leaf water potential across seven tree species

Physiological tradeoffs in the parameterization of a model of canopy transpiration

Effects of aggregated classifications of forest composition on estimates of evapotranspiration in a northern Wisconsin forest

Tree species effects on stand transpiration in northern Wisconsin




(c) 2024 D.S. Mackay