Working with Brazilian forester, Edna Gomes Tenório Guimarães, we installed four permanent transects, 50m by 1000m, adjacent to the eddy-covariance tower site (map). Three radial transects originate at the tower and run 1000m in the three predominant wind directions, northeast, east, and southeast. The fourth runs north-south, situated in the main footprint of the tower, intersecting the east-west transect about 300 m upwind. To permanently mark the area, stakes (PVC pipe) were installed every 50m to mark distance along the central transect line.
 

Large trees (diameter at breast height, DBH * 35 cm) located within 25 m on either side of the central transect line were identified, tagged and measured for diameter at breast height (1.30m above the ground). Smaller trees (between 10 and 35 cm DBH) were also identified, tagged and measured in a narrower swath, 5 m on either side of the central transect line.  We used the smaller survey area for small trees due to the large number of stems in that size class. Estimates of x-y coordinates for each tree stem were recorded in terms of the distances along (x) and perpendicular to (y) each transect line. Mateiros from EMBRAPA, Erly Pedroso, and Nilson de Souza Carvalho identified trees by common name.  All trees with significant buttresses were measured above the buttresses by using an aluminum ladder. Two student interns, Jorge José Pinheiro Macêdo, and Ocidne Franck A. Magalhães, were trained in basic forest mensuration techniques and data assembly and provided field assistance.  In a subsequent visit in the fall of 1999, Nelson Rosa of the Museo Gueldi, Belèm collected specimens and provided botanical identifications.  The complete data set can be found on the LBA Ecology web page.

In the four 50m by 1000m transects, we sampled a total of 20 ha containing 945 large (DBH * 35 cm) trees, an average large tree number density of 47 trees/ha.  The four smaller 10m by 1000m (1 ha) sub-transects also contained a total of 1643 small trees (10cm < DBH < 35cm), an average number density of 413 trees/ha.  Overall, we inventoried ~260 species, distributed over 47 families.  The distributions of tree population and biomass densities by size class are shown in Figure 2.

All raw data have been deposited with IBAMA in Santarem, in paper and spreadsheet format.  Summaries of the initial results (species list, summaries of frequency and basal area by transect, lists of common families and species encountered) of the census were presented in a report distributed to IBAMA, EMBRAPA (Santarèm and Belterra offices), student interns, and LBA-Ecology Project Scientist, Michael Keller.  A copy remains available for perusal in the LBA-Ecology Laboratory in Santarèm.

Updated 1 March 2001