Lichstein Lab

Each year, humans emit roughly 8 billion metric tons (gigatons, Gt) of carbon to the atmosphere by burning fossil fuels and another 2 Gt from deforestation. Terrestrial ecosystems absorb about 25% of these emissions, thereby reducing the growth rate of atmospheric CO₂ and mitigating anthropogenic climate change. This global terrestrial ‘carbon sink’ is not simply a consequence of photosynthesis and ecosystem carbon storage. On the contrary, global ecosystems were roughly ‘carbon neutral’ in their exchange with the atmosphere for thousands of years prior to the industrial revolution. Thus, the global terrestrial carbon sink reflects a disequilibrium between ecosystems and the atmosphere that is ultimately caused by human activities.

Multiple mechanisms likely contribute to the global terrestrial carbon sink, including ‘CO₂ fertilization’ (i.e., the stimulation of photosynthesis by rising atmospheric CO₂) and forest regrowth from previous land use. However, we have only a limited understanding of the relative importance of these and other mechanisms in explaining the global terrestrial carbon sink. This lack of mechanistic understanding leads to large uncertainty in how terrestrial ecosystems will respond over coming decades to changes in climate and other environmental factors. This uncertainty hinders prediction and planning in the context of sea-level rise, food security, and biodiversity conservation. Our research group aims to better understand the mechanisms that control terrestrial ecosystem responses to global change and the role of ecosystems in regulating Earth’s climate.

Much of our research focuses on quantifying and understanding changes in U.S. forests over recent decades. Our primary data source for this research is the national-scale Forest Inventory and Analysis (FIA) dataset collected by the U.S. Forest Service. The FIA program collects data in ~100,000 permanent sample plots that are systematically distributed across public and private U.S. forest lands. We are using these data to study changes in carbon dynamics, tree species composition, and tree demographic rates (growth, mortality, and recruitment).

A second line of research focuses on improving the vegetation components of Earth System Models, which are used to project future changes in climate and sea-level. We are especially interested in how plant functional diversity (the component of biodiversity related to plant physiology, form, and function) and plant demography affect the terrestrial carbon cycle and thus climate. This research involves studying patterns of functional trait variation within and among plant species and exploring how trait variation and ecological processes can be more realistically represented in Earth System Models.

Beyond these specific focus areas, we are broadly interested in community and ecosystem ecology, how biodiversity is maintained in ecosystems, and the role of biodiversity in ecosystem functioning.

Jeremy Lichstein, Professor
317 Carr Hall
Department of Biology
University of Florida
Gainesville, FL 32611-8525
Phone: (352) 392-1540
Email: jlichstein@ufl.edu