Feedbacks Between Tropical Forests, Climate, and Earth’s Carbon Budget Jacob Eisenberg

Feedbacks Between Tropical
Forests, Climate, and Earth’s Carbon
Jacob Eisenberg
Advised by David Medvigy,
Background Information
• Tropical Forests are essential to Earth’s climate, and
specifically the carbon cycle
• Very substantial carbon sink (40% of Carbon in terrestrial
• Important to maintain this to mitigate Carbon Dioxide in
• Unique relationship with climate change, as they both exert
influence on each other.
• Coupling Effect
• Need to better understand this relationship to predict what will
How can we do this?
One popular approach is computer models.
Ecosystem Demography Model (ED2).
Can work on a smaller scale
Uses data about the ecosystem on the plot of land (weather,
tree size, tree species, soil, etc.) to model growth and carbon
sequestration of the forest.
• Difficult to know all parameters, relationships between
• To obtain a more accurate method of looking forward, we have
to look backwards.
Checking the Model
• One way to check the accuracy of the model is to compare the
model results with known data.
• If the results are similar, it suggests the model is on the right
• If not, it suggests that some parameters or relationships present
in the model are not representative of the real world dynamics
• This process is what I spent the majority of my internship
• Initialization, how to run it, how to interpret results
Running the Model
Step 1: Initialization
Figure of Trees
in a plot in
Brazil, grouping
trees by
diameter, and
computing the
total basal area
of all trees in a
given diameter
class. Colors
different wood
densities. This
is necessary to
initialize model.
Step 2: Running/Processing Results
• Pss/css files
• Remote access to computer
• Results Files
• Data Analysis in MATLAB
• At first, results were very different than observed data.
• Mistakes, changing some parameters, results improved
• Main results of interest were Above Ground Biomass, Leaf
Are Index, and Basal Area.
• Three decade-long runs, isolating meteorological data
• Supposed discrete jump in AGB in late 80s
• Also did runs from scratch (just seedlings)
Shows the LAI in a run started from scratch in Shows the AGB in a run started from scratch.
three different decades. Results were similar, AGB was noticeably higher in the 90s than
and also reasonable.
the 80s, supporting the discrete jump
Basal Area in a run started
from scratch. Clearly
increase until it reaches an
equilibrium. (Ignore late
drop) This plot of forest
had a recorded basal area
of 26 m^2, which is nearly
identical to the results of
the model.
• When run from scratch, the model is accurate.
• The results suggest that AGB did increase from the 80s to 90s
• However, when the model was run with the current ecosystem
in a given plot as the starting point, the results were not as
• Could be a problem with data (first person to use this database
with this model)
• Still many interactions/relationships in tropical forests
scientists do not understand
Importance of Computer models
Original Research
Lab Group Environment
Future Plans
Thank you to PEI, Professor Medvigy, and his research group!