Associated Terrestrial Measurements

To help determine the ecological controls on carbon balance in the Tapajos National Forest, we have undertaken ecological sampling to complement gas exchange measurements.  After an initial survey of trees in 1999, we began long-term monitoring of tree growth and litter production.
 
 
Biomass Survey
In July of 1999, we surveyed 20 ha of forest in the tower "footprint."  Over 2500 trees were measured, identified and mapped in four transects (1000m) east of the tower. Overall, trees were distruibuted among ~260 species within ~50 families.  Common species encountered include Manilkara huberi, Coussarea racemosa, Sclerolobium chrysophyllum, Protium sp., Couratari stellata and Erisma uncinatum. An inventory report contains a complete species list and summary tables (In Portuguese).   Final survey results are also available on the LBA Ecology web page. For more information on survey design and implementation, view transect map and survey methods. 

 
Wood Increment

For more detailed measurements of incremental growth, metal dendrometer bands were placed on a random stratified sub-sample of 1000 trees in December of 1999.  The sample included trees from all taxonomic groups and all trees greater than 90 cm DBH. Dendrometers are currently measured every six weeks and so far show a strong seasonal pattern of growth. Some preliminary results in power point poster format can be found in our data exchange. 
 
 

Litter measurements

In July of 2000, litter baskets were randomly placed in all transects (10 per transect, 40 total).  Litter is collected biweekly and sorted, dried and weighed.  Chemistry measurements (C/N/P) and select isotopic measurements (13C and 14C) are planned. 
Dendrometer bands wrap like a belt around a tree at breast height. A spring secures the ends and two measuring points are punched where the band overlaps. As the tree grows, the spring stretches, and the measuring points are pulled apart. By measuring this increasing distance between points, we can accurately determine the increase in the tree’s diameter, which can be scaled up to whole tree growth. Most trees have only one dendrometer, but this tree is being used to test different dendrometer styles.

 


Forest and Atmospheric Measurements
Atmospheric Sciences
Harvard University

Updated 1 March 2001