Treesearch

The Luquillo Mountains are affected by a wide array of environmental processes and distnrbances. Events that concurrently alter the environmental space of several different areas of the Luquillo Mountains occur every 2 to 5 years. Events such as hurricanes that cause widespread environmental modification occur once every 20 to 60 years. The most common disturbance-generating weather systems that affect the Luquillo Mountains are (1) cyclonic systems, (2) noncyclonic intertropical systems, (3) extratropical frontal systems, and ( 4) large-scale coupled oceanatmospheric events (e.g., North...

Antillean dry forests have experienced high levels of human impact for almost five centuries. Economic changes in the second half of the 20th century have facilitated forest recovery in Puerto Rico. We quantified the extent of forest cover and the community composition of representative forest fragments in the subtropical dry forest life zone (sensu Holdridge, 1967) in southwestern Puerto Rico. Forest cover, which was largely eliminated by the 1940s, stood at 48% in the western dry forest life zone in 1993. Fragments varied in land-use history and supported from 1% to 86% of the reference...

The rapid disruption of tropical forests probably imperils global biodiversity more than any other contemporary phenomenon1–3. With deforestation advancing quickly, protected areas are increasingly becoming final refuges for threatened species and natural ecosystem processes. However, many protected areas in the tropics are themselves vulnerable to human encroachment and other environmental stresses4–9. As pressures mount, it is vital to know whether existing reserves can sustain their biodiversity. A critical constraint in addressing this question has been that data describing a broad...

While testing genetic sexing techniques in Ovenbirds (Seiurus aurocapilla),we found a genetic polymorphism in the ATP5A1 gene in 38% of individuals. The Z ' allele included changes in both intronic and exonic portions of the sequenced region, but there was no evidence that this changed the resulting ATP synthase product. Males that had one or more copies of this allele had higher relative bodymass (mass corrected for size) than other genotypes. This allele was unrelated to stable isotope signatures, and so was not a useful predictor of latitude within the eastern portion of the Ovenbird...