Forests cover some 65% of the reserve concentrated in three large blocks (625, 550, 140 ha). All of the forests were logged and there are no undisturbed or “pristine” forests remaining. Some forests dominated by early succession plant species are clearly forests re-colonizing previously farmed land, while others retain elements of the mature forest community indicating that they were never completely deforested in the 20th century, but rather selectively, even if intensively, logged. Except for those forests consisting entirely of pioneer species, forests are variegated mosaics of vegetation with individual stands of trees reflecting the disturbance history of the site. It is common for forest structure to change over small spatial scales. Table 1 details the 5 forest types found in the reserve and the percentage of the forest each type occupies of the main forest blocks.
Table 1 – Forest classification REM, Bahia, Brazil. List of tree species from Flesher (2012) and Rocha (2011); % = percent of REM three main forest blocks supporting this type of forest (N= 27,050 m of trails).
Other habitat types
There is a small patch of mangrove forest at the northeastern edge of the reserve at the mouth of the Canal de Serinhaem. Rhizophora and Avicennia species dominate the mangrove community.
Varzeas (freshwater cattail wetlands)
Low areas along streams that accumulate water create an environment of permanently moist soils ideal for sedges, grasses, reeds, and ferns. Characteristic of these wetlands are dense stands of cattails growing to 1.5-2 m, punctuated with bushes, shrubs and trees on small islands of dry land. The vegetation along the varzea edge is typically a 2-8 m wide dense growth of pioneer trees and bushes reaching 1-12 m. All of the major waterways have varzeas.
Rubber (Hevea brasiliensis) groves
This region is one of the most productive rubber cultivating areas in Brazil, with a large amount of land dedicated to this crop and rubber groves occupy approximately 15% of the reserve landscape. Rubber trees are generally planted at an average density of 476-500 trees/ha with a spacing of 7m x 3m and 8m x 2.5m, respectively. Rubber trees start to be tapped 7 years after planting and once producing can be bled throughout the year, although production drops when the trees change their leaves and during prolonged periods of heavy rain. Cut with a special blade that makes long diagonal grooves in the trunk, the latex bleeds down the groove into a spout and fills a collecting cup attached to the tree with a wire vise. Workers visit each tree every 3-5 days, collecting the condensed rubber in the cup and then cutting a new groove to start the process again, working 850-900 trees/day. Trees can be bled for decades by shifting around the trunk and letting cut sections scar over. Sometimes a hormone is applied to the trees to induce greater productivity.
The common practice of cutting back the inter-row vegetation in the rubber groves was stopped after the creation of the reserve and the areas between the rubber rows now consists of dense secondary growth dominated by pioneer species (Miconia, Henrietta, Cecropia, Inga, Schefflera, Senna, Piper, Solanum, Rauvolfia, Bauhinia, Heliconia, and Cyperus grasses). The upper canopy of the inter-rows varies with the age of the stand, reaching 2-4 m in the younger and up to 10+ m in the older stands. In some places the pioneer trees support thick mats of thin vines. In the Michelin rubber groves outside of the reserve (approximately 1,000 ha), the height of the inter-row vegetation varies according to the bush clearing cycle. Inter-row vegetation is mostly allowed to grow for 6-12 months before clearing and varies from low grasses to thickets of grasses, Heliconias, bushes, and trees reaching 2+ m. We have planted 100,000 native forest trees of >210 species in 275 ha of the reserve’s rubber groves as part of our forest restoration program. Some of the reserve rubber groves have already been abandoned with the last groves scheduled to be abandoned in 2024.