Treesearch

The venom alkaloids from the workers of nine collections of Solenopsis (Diplorhoptrum) from California contain either (5E,9E)-3-hexyl-5- methylindolizidine (Ic) or (SZ,9E)-3-hexyl-5-methylindolizidine (Id) along with cis-2-methyl-6-nonylpiperidine. The structures of these compounds were determined from their mass spectra and by comparison of their GC-FTIR spectra with those of a synthetic mixture. In view of the facts that a third diastereomer of 3-hexyl-5-methylindolizidine had been reported in previous collections of Solenopsis (Diplorhoptrum) queens from Puerto Rico, and that indolizidin...

We studied microhabitat use, foraging and social behavior of Broad-billed (Todus subulatus)a nd Narrow-billed (T. angustirostrisT) odies in two areaso f sympatry in the Cordillera Central of the Dominican Republic. Solitary Broad-billed and Narrow-billed Todies occupied distinct microhabitats in both shade coffee plantations and native pine forest while generally sharing similar foraging strategies. In both habitats, Broad-billed Todies foraged higher in the vegetation and occurred in more outer horizontal positions with lower foliage density than did their congener. Movement rates and...

The Revised Universal Soil Loss Equation (RUSLE) was used in conjunction with a Geographic Information System to determine the influence of land use and other environmental factors on soil erosion in the Guadiana watershed in Puerto Rico. Mean annual erosion, suspended sediment discharge, and the rainfall-erosion factor of the RUSLE increased with annual rainfall. Median soil erosion rates varied among the seven land uses: bare soil (534 Mg ha-1 yr-1), open canopy forest (26 Mg ha-1 yr-1), agriculture (22 Mgha-1 yr -1), pasture (17 Mg ha -1 yr -1), less dense urban (15 Mg ha-1 yr -1),...

Information on dispersali s critical for understandingt he population dynamicso f birds. We estimated breeding and natal dispersal in two studies of a population of the Puerto Rican Vireo (Vireo latimeri) that is in danger of local extirpation due to low reproductive success from 7.1-29% of adult males and 12.5 - 25% of adult females changed territories between breeding seasons. The median breeding dispersal distance of 12 birds (7 males, 2 females, and 3 of unknowns ex) was3 70 m (range 110-560 m). Four fledglings dispersed a median distance of 490 m from their natal nests to breeding...

Landslides are common in steep mountainous areas of Puerto Rico where mean annual rainfall and the frequency of intense storms are high. Each year, landslides cause extensive damage to property and occasionally result in loss of life. Average population density is high, 422 peoplerkm2, and is increasing. This increase in population density is accompanied by growing stress on the natural environment and physical infrastructure. As a result, human populations are more vulnerable to landslide hazards. The Blanco, Cibuco, and Coamo study areas range in surface area from 276 to 350 km2 and...

We quantified foraging behavior of 19 bird species in shade coffee plantations in the Dominican Republic to document and evaluate their use of food resources in the shade overstory relative to the coffee understory. All species were observed foraging in the Znga “era overstory, and 18 of the 19 species had median foraging heights significantly above the median maximum coffee height. Eight species (42%) foraged exclusively in the canopy or subcanopy and not in the coffee understory. No species foraged exclusively in the coffee, although the Narrow-billed Tody (To&s angustirostn’s) foraged...

The impacts of road construction and the spread of exotic vegetation, which are common threats to upper elevation tropical forests, were evaluated in the subtropical cloud forests of Puerto Rico. The vegetation, soil and microclimate of 6-month-old road®lls, 35-year-old road®lls and mature forest with and without grass understories were compared. Recent road®lls had higher light levels, soil temperatures, bulk densities, larger pools of exchangeable soil nutrients and higher soil oxygen concentrations; but lower soil moisture, soil organic matter and total soil N than the mature forest. On...

Mangrove forests are tough ecosystems to invade because few species can tolerate the hydrological and edaphic conditions that prevail in mangrove habitats. The small pantropical mangrove species pool is also the basis for asserting that mangrove forests are easy to rehabilitate, at least in terms of tree species composition. The high complexity of the animal and microbial component of mangrove ecosystems is not addressed in this article. The following questions are useful as a guide for evaluating the invasion of plant species into mangrove habitats: (1) Is the invading species a halophyte?...

Although it is one of the most spectacular geologic features in PR, the vegetation of Cañon de San Cristobal was seriously disturbed over the last century and a half by subsistence farming, grazing, and wood cutting. Now that agricultural activity has nearly ceased and the cayon is partially protected, the vegetation is rapidly recovering. At the request of the conservation trust of puerto rico, which owns about two thirds of the cayon, personnel of the U.S Deparment of Agriculture, Forest service, International Institute of Tropical Forestry, conducted a vegetation survey of the entire...