Treesearch

The low available phosphorus (P) pools typical of highly weathered tropical forest soils are thought to result from a combination of export of phosphorus via erosion and leaching as well as chemical reactions resulting in physically and chemically protected P compounds. Despite the low apparent P availability, these soils support some of the highest terrestrial net primary productivity globally. We followed different P fractions after P additions to two soil types, sandy loam and sandy clay, over 1 year in a lowland Amazonian forest. Of all the soil P fractions measured, only the NaHCO3...

[1] A new three-dimensional version of the Carnegie-Ames-Stanford Approach (CASA) ecosystem model (CASA-3D) was developed to simulate regional carbon cycling in tropical forest ecosystems after disturbances such as logging. CASA-3D has the following new features: (1) an alternative approach for calculating absorbed photosynthetically active radiation (APAR) using new high-resolution satellite images of forest canopy gap fraction; (2) a pulse disturbance module to modify aboveground carbon pools following forest disturbance; (3) a regrowth module that simulates changes in community compositi...

Taxon cycling, i.e. sequential phases of expansions and contractions in species’ distributions associated with ecological or morphological shifts, are postulated to characterize dynamic biogeographic histories in various island faunas. The Caribbean freshwater shrimp assemblage is mostly widespread and sympatric throughout the region, although one species (Atyidae: Atya lanipes) is geographically restricted and ecologically and morphologically differentiated from other Atya species. Using patterns of nucleotide variation at the COI mtDNA gene in five species of freshwater shrimp (A....

The endemic Puerto Rican crab, Epilobocera sinuatifrons (Pseudothelphusidae), has a freshwater-dependant life-history strategy, although the species has some capabilities for terrestrial movement as adults. In contrast to all other freshwater decapods on the island (e.g., caridean shrimp), E. sinuatifrons does not undertake amphidromous migration, and is restricted to purely freshwater habitats and adjacent riparian zones. As Puerto Rico has a dynamic geologic history, we predicted that both the life history of E. sinuatifrons and the geological history of the island would be important...

Extinctions of Caribbean animals were well underway during the period of Amerindian occupation and have continued since the arrival of Columbus. Despite high extinction rates, the Caribbean still retains high levels of terrestrial biodiversity and, for some taxa, exceptionally high levels of endemism relative to other parts of the world. The fate of the Caribbean’s biodiversity is considered especially precarious, given the region’s contribution of unique species to the Earth’s biodiversity and its high rate of habitat loss, which together qualify the region as a global biodiversity...

Secondary forest succession and tree planting are contributing to the recovery of the Cabo Rojo refuge (Headquarters and Salinas tracts) and Laguna Cartagena refuge (Lagoon and Tinaja tracts) of the Fish and Wildlife Service in southwestern Puerto Rico. About 80 species, mainly natives, have been planted on 44 ha during the past 25 y in an effort to reduce the threat of grass fires and to restore wildlife habitat. A 2007 survey of 9-y-old tree plantings on the Lagoon tract showed satisfactory growth rates for 16 native species. Multiple stems from individual trees at ground level were...

studied the reproductive success of the Puerto Rican Vireo (Vireo latimeri) from 1998 to 2000 in Maricao State Forest, a montane reserve in the southwestern part of Puerto Rico. No parasitism by the Shiny Cowbird (Molothrus bonariensis) was found but 63% of 38 active nests were depredated with an overall daily nest survival of 0.932  0.007 ( SE). Mean nest survival estimates following Hurricane Georges did not vary significantly before and after the hurricane. However, a return rate of only 39% was estimated for colormarked adults the year including the hurricane compared to 72% for the...

Analysis of 19-year-old planted Pinus caribaea var. hondurensis on clay and sandy soils in the mountains of Puerto Rico showed the suitability of both sites for tree growth to commercial size. Growth rates were compared with tree densities ranging from 278 to 2,500 trees per hectare and tree dbh’s (trunk diameters outside bark at breast height, 1.4 meters above ground on the upper side) from 10 to 40 cm. With angular spacing tree growth was found related to that of six equidistant adjacent trees. Frequent past remeasurements exposed tree growth trends with changes in the density of...

Dwarf forest in Puerto Rico’s Luquillo Mountains varies according to substrate and topography with very short, dense forest growing on exposed, rocky sites. High elevation level sites suffered considerable damage during past hurricanes whereas the trees on certain lower slopes were protected by ridges or spurs. Post-disturbance recovery of dwarf forest on two types of sample plots near East Peak was slow. Nearly 37 years after a 1968 airplane crash, Cyathea bryophila (R. Tryon) Proctor and Eugenia borinquensis Britton accounted for 71% of the 25.3 t ha−1 total aboveground dry weight...

Several species of Nearctic-Neotropical migratory songbirds appear to form roosting aggregations while on their wintering grounds but little is understood about the ecology of this behavior. We studied roosting behavior and patterns of roost habitat selection in the northern waterthrush Seiurus noveboracensis, during three winter years (2002
2004) in Puerto Rico using radio telemetry. Overall, red mangrove was selected for roosting disproportionately to its availability. Regardless of diurnal habitat used, 87% (n86) of northern waterthrush selected dense stands of coastal red mangrove for...