Research Overview (for specific projects,
clink links to the right)
My lab’s approach to plant ecology and evolution is based
on the underlying assumption that climate is a primary
selective agent. Our goal is to improve our understanding
of the physiological responses of plants to climate change,
and to determine the ecological and biogeochemical
consequences of those responses. Climate change is defined
broadly, as we are interested in biotic-abiotic
interactions from millennial scale climate change down to
the seasonal progression of weather fronts. Our physical
scale of study ranges from the subcellular to individuals,
ecosystems and landscapes up to the regional level where
physical and physiological processes modify the atmospheric
boundary layer. The scope and scale of our research
interfaces biochemistry, physiology, ecology, evolution and
the earth sciences, and hence necessitates
interdisciplinary collaboration that often includes, apart
from biologists, meteorologists and geochemists.
Our research both examines natural processes and develops
methods by which to measure them. A primary tool for
elucidation of these processes is the analysis of natural
abundance stable isotopes. Abiotic processes (e.g.
precipitation and biomass burning) and biotic processes
(e.g. photosynthesis and respiration) differentially affect
the stable isotope abundance of atmospheric CO2, O2 and
water. Hence, stable isotopes provide a tracer for
biological activity from the scale of a chloroplast to the
globe, and allow us to address questions of plant
physiological ecology and climate on a variety of temporal
and spatial scales. The analysis of stable isotopes both in
atmospheric air and in plant material allows us to estimate
plant and whole ecosystem responses to environmental
change, partition terrestrial versus oceanic photosynthesis
and assess changes in plant distribution and productivity
over daily to geological timescales.
Here are some specific questions that have motivated our
research in the past, and will continue to motivate our
thoughts into the future:
1) How do changes in abiotic inputs (e.g. CO2
concentration, precipitation, radiation) and the processes
of photosynthesis and respiration affect the carbon and
water cycles at ecosystem to regional scales?
2) What are/were the selective forces behind the
physiological and anatomical differences between C3 and C4
plants (particularly grasses)? How are these differences
manifest in current and past distributions of C3 and C4
plants? How do intra-annual and inter-annual variations in
C3 and C4 distribution affect carbon and water cycles?
3) What are the mechanistic explanations for observed
differences in carbon and oxygen isotope signatures in
plants? Can we use these observations and the underlying
mechanisms to reconstruct plant and ecosystem responses to
past climatic change?
4) Can we use measurements of CO2, H2O and their isotopes
in the atmospheric boundary layer to measure regional-scale
photosynthetic, respiratory and fossil fuel contributions
to the global carbon cycle?
