PARENT SESSION
Contributed Oral Session 127: Forest Structure and Communities
Thursday, August 11, 1:30 PM - 5:00 PM, Meeting Room 513 A, Level 5, Palais des congrès de Montréal
Survival and recovery of dry forests in the Caribbean - the role of forest fragments.
Ramjohn, Ian1, Murphy, Peter2, 1 University of Oklahoma, Norman, OK, USA2 Michigan State University, East Lansing, MI, USA
ABSTRACT- Caribbean dry forests are an endangered ecosystem. The Caribbean has a long history of human settlement and some of the highest population densities in the world. The future of Caribbean dry forests lies in their ability to recover after disturbance. On the island of Puerto Rico, forest cover has recovered from a low of <10% in the 1940s to over 35%. In the dry southwest of the island, a substantial amount of forest has returned to the landscape. These forests differ in land-use history - some have experienced moderate disturbance (harvest of stems for fuel and fence posts) while others have recovered on abandoned agricultural land. Land-use has left a major imprint on these forests. Although species richness was a function of both area (R2=0.715) and land-use history, species composition was primarily a function of land-use history. Sites which had grown on abandoned agricultural land averaged far fewer plant species characteristic of Puerto Rican dry forest (24 ± 2.4%; mean ± 1 standard error) than did sites that had been less severely disturbed (56 ± 3.6%). The four most common species in mature Puerto Rican dry forest were present in 63-73% of the sites with moderate disturbance histories, but were only present in 6-13% of the sites which had re-grown on abandoned agricultural land. The recovery of disturbed dry forests in Puerto Rico appears to be a function of disturbance history. In addition, it appears that barriers exist to the recolonization of these areas by forest dominants. New forests dominated by the introduced legume, Leucaena leucocephala differed in species composition from those dominated by the native Pisonia albida. Characteristics of the species which first colonize these sites may have a profound influence on the recovery of the individual sites.
Key words: tropical dry forest, forest recovery, Puerto Rico