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LC-04 Abstract

The Effects of Tropical Forest Conversion: Ecological Research in the Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA)

Marcos Costa — UFV - Universidade Federal de Višosa (SA-PI)
Jonathan A. Foley — Institute on the Environment (US-PI)

Objectives





We have proposed a low-cost effort, focused on LBA-ECO research agendas, that will

build upon our ongoing activities in land surface and ecosystem modeling. Our group is

currently funded as an EOS Interdisciplinary Science Team (IDS) by NASA's Mission to

Planet Earth.





Our group is currently engaged in an effort to develop an integrated dynamical

biosphere model -- the Integrated Biosphere Simulator (IBIS). Our modeling approach

reconciles the disparity of the existing land surface packages and terrestrial biosphere

models by representing a more complete hierarchy of ecosystem phenomena, including:









  1. land surface physics (energy, water, and momentum exchange within the

    soil-vegetation-atmosphere system)




  2. canopy gas exchange (photosynthesis, respiration, and stomatal behavior)




  3. plant phenology (seasonal cycles of leaf development, leaf senescence, and plant

    activity)




  4. whole-plant physiology (allocation of carbon and nitrogen, plant growth, tissue

    turnover, and age-dependent changes)




  5. vegetation dynamics (recruitment, competition for resources, mortality,

    disturbances, and gap formation)




  6. carbon and nitrogen cycling (flow of carbon and nitrogen between the atmosphere,

    vegetation, litter, and soils).






Initial versions of IBIS have been used to investigate global patterns of water

balance, carbon cycling, and vegetation cover, as well as the potential impact of

increasing CO2 concentrations on the hydrology of the Amazon basin. We are

developing a more sophisticated version of IBIS for simulations of global biogeochemical

processes, vegetation dynamics, and terrestrial hydrology as part of our funded NASA EOS

Interdisciplinary Science Investigation.





Working with other LBA-ECO investigators, we hope to use our integrated terrestrial

biosphere model to evaluate changes in land surface processes, ecosystem dynamics, and

terrestrial carbon storage in response to land use activities in Amazonia.





We anticipate that these efforts will proceed along four areas:









  1. Develop an historical perspective of land cover change in Amazonia. Using a

    combination of remote sensing products (i.e., Landsat and AVHRR data), long-term national

    inventory data, and other ancillary data, one can construct an empirically-based model of

    land use activity and land cover conversion for the Amazon basin.



  2. We plan to work with LBA-ECO investigators in developing land use and land cover

    change scenarios for the Amazon region. In addition, a graduate student in our group,

    Navin Ramankutty, is currently building a land-use model for reconstructing global

    patterns of land use and land cover change during the last 100 years. This work could be

    extended, at little cost, to focus on the Amazon basin as well.





  3. Use land use scenarios as a driver of the IBIS dynamic biosphere model. Using our

    IBIS dynamic biosphere model, and land cover change scenarios, we can examine the dynamic

    processes occurring within terrestrial ecosystems that give rise to carbon sources and

    sinks. Using IBIS to simulate dynamic ecosystem processes will provide several advantages

    over other modeling approaches, because it simulates land surface processes, canopy

    physiology and gas exchanges, biogeochemical cycling, and vegetation dynamics in a single,

    physically-consistent modeling framework.



  4. We plan to collaborate with LBA-ECO investigators to develop appropriate simulation

    experiments, and to coordinate data exchange and model intercomparison

    activities.





  5. Validate model simulations against hierarchical of surface and remotely sensed

    observations.
    Working with data generated by LBA projects, we will be able to compare

    our simulations of land surface processes and ecosystem dynamics against a full suite of

    observations. These observations include (we hope) streamflow data, tower flux data,

    isotope samples (i.e., 13C/12C, 18O/16O), and

    satellite measures (including data from Landsat, AVHRR, and MODIS). Our integrated

    biosphere modeling approach, unlike other modeling frameworks, will facilitate a more

    complete validation procedure by linking direct biophysical measures (e.g., canopy

    spectral reflectance, energy and water fluxes, and isotopic fractionation) and longer-term

    ecological, biogeochemical and hydrological measures (e.g., leaf area index, biomass, soil

    carbon, runoff and river discharge).






  6. Evaluate response of net carbon exchange to land use scenarios. Finally, we will be

    able to examine how changes in land use (past, present, and future) may affect the gross

    carbon budget of the Amazonian region.









To facilitate communication and collaboration with Brazilian scientists, we will

coordinate our efforts with Prof. Marcos Costa, who is currently working with Foley's

group at Wisconsin. Costa is a Professor in the Department of Agricultural Engineering at

the Federal University of Višosa.


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