Ecohydrology
Group
Department
of Geography
& Department of Environment and
Sustainability
Welcome!
My name is D. Scott Mackay and I am a
Professor of Ecohydrology at the
University at Buffalo (SUNY). My
research interests are in plant
responses to environmental stress and
the role of plants in water cycling,
which I study using plant hydraulics,
biophysical modeling, and Bayesian
analysis. I examine how drought, heat,
and biotic disturbances combine to
threaten forests, crops, and the
security of plant-based food, fiber,
and energy production. I take a systems
approach, build biophysical
process-based
models, and synthesize data from
sensors, biometric measurements, and
genomics. Collectively, these
approaches help us reveal emergent
plant traits, water and carbon
cycling dynamics, and plant-microbe
associations. Please read
on to learn more about my research
projects and the published findings
from this work.
TREES Biophysical
Process Model
I
developed the Terrestrial Regional
Ecosystem Exchange Simulator
(TREES), a physiologically
sophisticated plant biophysical
process based model, to simulate
carbon, water, and energy exchange
between terrestrial ecosystems and
the atmosphere. A feature of TREES,
novel at at the time of its
development (Mackay et al.,
2015), is the coupling of
stomatal conductance to xylem
cavitation. This allows the model to
predict aboveground and belowground
physiological responses to drought.
It mechanistically simulates the
continuous movement of water from
the soil, through plant roots and
xylem, and out into the atmosphere
to predict drought stress, plant
growth, and mortality. This allows
researchers to quantify how forests
and other biomes respond to
environmental shifts, climate
dynamics, and disturbance agents. A
second feature of TREES, which was
novel at the time of development (Mackay et al.,
2020), is transience in root
growth determined by feedback with
the plant hydraulic system. This
gives researchers a powerful tool
for refining mechanisms of dynamic
root function during drought.
Heat,
Drought, and Tree Mortality
Healthy
forests are carbon sinks, but
when trees die they become
carbon sources. Forests also
transpire a large fraction of
the global average
precipitation falling on land
areas, and so their demise
alters the land-atmosphere
energy balance. Published
results from this project are:
Scientists
have long wanted to be able to peer
into the subsurface to see how root
processes interact with other
processes occurring below ground. We
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 and sustain their
access to reliable water sources? Here you can read
more about these findings:
Subsurface
hydrology has received less
attention compared to above
ground processes for predicting
the physiological responses of
plants to drought. Our
work fills this gap by
considering the integrated
systems of plant hydraulics and
groundwater hydrology. A product of
this research was
ParFlow-TREES, an advanced,
coupled ecohydrological model
that simulates the movement of
water from deep groundwater,
through the soil, up
individual plants arranged
across the landscape, and into
the atmosphere. The model
bridges the gap between
hydrology and plant physiology
so that researchers can
evaluate how vascular plants
use water and respond to
drought at scales of
individuals, stands,
hillslopes, watersheds, and
regions. The following
publications provide a deeper
look at the findings from this
project:
Biotic
disturbances are an
integral part of ecosystem
responses to environmental
dynamics, but the full
extent of their effects on
integrated systems is only
partly known. A major
finding of this work is
that some ecosystems are
resilient to biotic
disturbance because of
hydrologic refugia while
others are capable of
rapid recovery from even
the most extreme biotic
epidemics. More details
are available in the
following publications:
Plant
traits interact with
environmental conditions
to affect plant growth and
productivity. By examining
these interactions using
crop species and
biophysical process-based
models, and manipulating both plant traits and their
environment, we
are able to gain a deeper
understanding of
mechanisms. This provides
a robust hypothesis
testing framework to study
traits that are
transferable to natural
settings and novel
environmental conditions.
Here you
can read about these
findings:
We ask
how species, plant age,
disturbance, and spatial
gradients associated
with edaphic,
topographic, and
micrometeorologic
dynamics affect
evapotranspiration. We
show that
evapotranspiration
must consider hidden
sources of water in
forested wetlands,
which are hard to
distinguish from
upland forests when
using remote sensing.
We also show that
spatial dynamics tree
transpiration can be
explained by dynamics
of vapor pressure
deficit, and that
significant
variability in
stomatal conductance
in forests is
attributed to spatial
dynamics of
competition for light.
More details are found
in the following
publications:
