Project Goals The goal of this study is to establish the range of tree species at Cloudbridge, to estimate their abundance, and to learn how the different species are distributed within the forest. To begin to understand the original composition of the forests we will take an inventory of the trees in several small areas distributed around Cloudbridge South and North. To achieve this we will record tree species, size, and location thereby establishing the relative abundance of each species and how that species is distributed. This inventory will be carried out both in primary forest and also in secondary forest to help us understand how the cloud forest tends to restructure itself after human intervention. The results of this inventory will help guide our efforts, and similar efforts elsewhere, to restore the forest. Background  In
a now classic paper published in 1979, Stephen Hubbell showed that the
then commonly held notion that tropical tree species are uniformly
distributed at low densities was wrong; at least in the tropical dry
forest of Guanacaste Province, Costa Rica. His study covered an area of
13.4 hectares and included about 16,000 trees with diameters greater
than 2 cm (6000 greater than 5 cm) that were separated into 135
species. He plotted the distribution of both the juvenile and adult
trees of each species. He found that for the 30 most common
species the average adult is clearly found aggregated with other adults
and juveniles. In the rarest species the aggregation was even more
pronounced. In the other common species the distribution was random.In a larger study at six different tropical sites covering dry deciduous to wet evergreen forest on two continents, Condit et al (2000) showed that nearly all of the 1768 tree species were more aggregated than a random distribution with the rare species being more aggregated than the common species. Pitman et al (2001) in a study of two widely separated Amazonian tropical forests, found that most species were rare (<1 tree/hectare) and that a few of the most common species dominated the forests and were locally aggregated. Furthermore, they found that a third of the most common species were found in both habitats separated by 1400 km; the similarities of the two sites were greater than expected. They noted that this kind of tree distribution is qualitatively what one finds in temperate forests, only the tropical forests have more species. With our proposed inventory of the Cloudbridge forest we will establish which tree species are present and whether or not the members of each species appear to be relatively aggregated as found by Hubbell and Condit et al, and whether or not most of the species are relatively rare as Pitman et al found. In addition, it will be interesting to see if two widely separated cloud forests, such as Cloudbridge and Monteverde (see Haber et al, 2000), share some of the most common species (as Pitman et al found in the Amazon). These results are important in deciding what species to plant and how they should be distributed in the reforestation of formerly agricultural land at reforestation projects such as Cloudbridge. One additional point is that Hubbell concluded from his study that the forest was in a relatively nonequilibrium state. This conclusion was challenged in a study by Terborgh et al (1996), in which he found to the contrary that tropical forests tend to return rapidly to an equilibrium state. While our study cannot address this issue, we can make observations from our comparison of primary and secondary forest, and by replications of this study over time. Methods Overall, the plan is to establish the range and distribution of tree species at Cloudbridge.
References Condit, R. et al, “Spatial Patterns in the Distribution of Tropical Tree Species,” Science, Vol 288, 26 May 2000, pp1414 – 1418. Haber, W. et al, An Introduction to Cloud Forest Trees, 2nd ed., Mountain Gem Publications, 2000. Hubbell, S.P., “Tree Dispersion, Abundance, and Diversity in a Tropical Dry Forest,” Science, Vol 203, No 4387, 30 March 1979, pp1299 – 1309. Pitman, N.C.A. et al, “Dominance and Distribution of Tree Species in Upper Amazonian Terra Firme Forests,” Ecology, 82 (8), 2001, pp 2101 – 2117. Terborgh, J. et al, “Tropical Tree Communities: A Test of the Nonequilibrium Hypothesis,” Ecology, 77 (2), 1996, pp 561 – 567. Reseachers must bring independent funding for their projects, including travel and living expenses. Send us some information about your research qualifications, what you wish to study, and when you can come. If your project is accepted, we'll assist in finding accommodation and provide access to the reserve. We'll also publish the results of the research on the Cloudbridge website. To discuss your ideas, contact to Ian & Genevieve Giddy (see the contact page). |
In the first stage of this project