{"id":22,"date":"2012-09-05T11:22:33","date_gmt":"2012-09-05T15:22:33","guid":{"rendered":"https:\/\/people.clas.ufl.edu\/template\/?page_id=22"},"modified":"2026-03-19T08:27:18","modified_gmt":"2026-03-19T12:27:18","slug":"research","status":"publish","type":"page","link":"https:\/\/people.clas.ufl.edu\/jlichstein\/research\/","title":{"rendered":"Research"},"content":{"rendered":"\r\n
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Research<\/h1>\n\n\n\n\n\n\n
\"jwl_siberia_camp4\"<\/td>\n\"bristlecone_grove_small\"<\/td>\n\"dougfir_wide_small\"<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n\n\n\n

Overview<\/h3>\n\n\n\n

We are broadly interested in the factors that control forest diversity and function (e.g., carbon storage) and the response of these ecosystem properties to disturbance, climate change, rising atmospheric CO<\/p>\n\n\n\n2<\/sub>\n\n\n\n

\u00a0levels, and other aspects of global change.<\/p>\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
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Themes<\/h3>\n
\"Joyce
<a href=”https:\/\/people.clas.ufl.edu\/jlichstein\/files\/joycekilmer.jpg” rel=”attachment wp-att-276″><\/a> Joyce Kilmer Memorial Forest.<br \/>North Carolina, USA.<\/figcaption><\/figure>\n
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<\/a>Forest response to increasing atmospheric CO2\"Mauna_Loa_CO2\"<\/a>
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Theory and experiments suggest that elevated CO2<\/sub>\u00a0should stimulate photosynthesis (“CO2<\/sub>\u00a0fertilization”), thereby offsetting some anthropogenic CO2<\/sub> emissions. However, the strength of the CO2<\/sub> fertilization effect in real forests, and the sustainability of this effect in the future as nitrogen and other factors become limiting, is uncertain. The policy implications are significant, as the emissions reductions required to stabilize atmospheric CO2<\/sub>\u00a0at a given target (e.g., 500 ppm) depends critically on the strength and sustainability of terrestrial carbon sinks. We are using long-term datasets from the U.S. Forest Service’s\u00a0FIA<\/a>\u00a0program to quantify how forest biomass and productivity have changed over recent decades, and to attribute these changes to forest succession (e.g., aging of secondary forests recovering from logging and\/or previous non-forest land-use) vs. CO2<\/sub>\u00a0fertilization and other non-age-related aspects of global change. See our paper on this topic<\/a>\u00a0published\u00a0in PNAS<\/i>.<\/p>

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<\/a>Improving global vegetation models\"LM3V_FIA_biomass_50yrs_small\"<\/a><\/h3>\n

Ecosystem response to global change spans a range of time scales, from fast-time-scale physiological processes such as the response of individual leaves to diurnal and seasonal temperature fluctuations, to slow-time-scale processes such as species turnover within broad functional types (e.g., tropical, temperate, or boreal trees). Variation in forest biomass and growth across spatial climate gradients contains valuable information that can be used to test and improve the representation of slow-time-scale processes in global vegetation models. We used U.S. Forest Inventory and Analysis (FIA<\/a>) data to optimize vegetation parameters in the NOAA-GFDL LM3V dynamic global vegetation model (which has now been replaced by the newer\u00a0LM3 model<\/a>). The figure on the right shows observed (FIA data) and predicted (LM3V model, prior to optimization) aboveground biomass (kg C m-2<\/sup>) in 50-year-old forests in the eastern USA. To learn more about this project, including some ideas on how to improve ecosystem models with multiple data streams, see our paper<\/a>\u00a0published\u00a0in Ecological Applications<\/i>, or download the poster<\/a>\u00a0we presented at the 2011\u00a0North American Carbon Program\u00a0meeting.<\/p>

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<\/a>Developing next-generation global vegetation models\"LM3-PPA_small\"<\/a>
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We have been involved in several efforts to test and develop a new class of vegetation models that could improve the representation of plant trait diversity and ecosystem dynamics in Earth system models. We worked as part of a team (led by collaborators at Princeton University and NOAA-GFDL) to develop the LM3-PPA dynamic global vegetation model<\/a>, which incorporated more realistic treatments of biodiversity and individual-tree level processes (e.g., height-structured competition for light) in the GFDL land model. We are also organizing a model intercomparison project (MIP) to study how trait diversity affects the response of tropical forests to drought.<\/p>\n

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<\/a>Forest disturbance<\/h3>\n
\"Post-fire
<a href=”https:\/\/people.clas.ufl.edu\/jlichstein\/files\/bonanza_creek_fire_small.jpg” rel=”attachment wp-att-272″><\/a> Post-fire regeneration in central Alaska.<\/figcaption><\/figure>\n

We are using a variety of empirical and theoretical approaches to better understand the role of natural and anthropogenic disturbances in determining forest community and ecosystem dynamics. Empirical work focuses on using forest inventory and other data sources to quantify disturbance impacts and to develop more realistic representations of tree mortality and disturbance in carbon-cycle models. Theoretical work focuses on the role of disturbance in allowing multiple tree species to coexist (Lichstein and Pacala 2011<\/a>).
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