Treesearch

Tropical soils are potentially the highest and least studied nitrous oxide (N2O) production areas in the world. The effect of water, nitrate and glucose additions on profile concentrations and episodic emissions of N2O for two volcanic soils in Costa Rica was examined. Magnitudes of episodic N2O pulses, as well as overall N2O emissions, varied considerably and consistently, depending on soil texture, soil water content, and kind and availability of substrates. Emission pulses began within 30 min, peaking no later than 8 h after wetting. Production in the soil occurred mainly in the layer...

Understanding of N2O fluxes to the atmosphere is complicated by interactions between chemical and physical controls on both production and movement of the gas. To better understand how N2O production is controlled in the soil, we measured concentrations of N2O and of the proximal controllers on its production in soil water and soil air in a field study in the Rio Icacos basin of the Luquillo Experimental Forest, Puerto Rico. A toposequence (ridge, slope-ridge break, slope, slope-riparian break, riparian, and streambank) was used that has been previously characterized for groundwater...

The effects of changes in tropical land use on soil emissions of nitrous oxide (N2O) and nitric oxide (NO) are not well understood. We examined emissions of N2O and NO and their relationships to land use and forest composition, litterfall, soil nitrogen (N) pools and turnover, soil moisture, and patterns of carbon (C) cycling in a lower montane, subtropical wet region of Puerto Rico. Fluxes of N2O and NO were measured monthly for over 1 year in old (more than 60 years old) pastures, early- and mid-successional forests previously in pasture, and late-successional forests not known to have...

CLIMATE CHANGE CAN AFFECT FORESTS BY ALTERING THE FREQUENCY, INTENSITY, DURATION, AND TIMING OF FIRE, DROUGHT, INTRODUCED SPECIES, INSECT AND PATHOGEN OUTBREAKS, HURRICANES, WINDSTORMS, ICE STORMS, OR LANDSLIDES

Dietary habits of the Puerto Rican blindsnake Typhlops platycephalus were studied by analysis of gastrointestinal tract contents and scats. Ant species (the principal prey taxon) were surveyed concurrently with the collection of the blindsnakes to determine what proportion of the species were used as prey. Typhlops platycephalus fed on 14 of 30 ant species found in the field and on two additional ant species that we did not find in the field. Individual snakes often feed on more than one prey species. Adult ants were most commonly found in the gastrointestinal tract and scats, although...

There are few reports of parasitoids of Aculeate Hymenoptera for Puerto Rico (Wolcott, 1948). Parasitoids are potentially significant control agents of other insect species, and iti important to know their distribution and hosts . The parasitic species reported here have not previously been recorded from Puerto Rico. These parasitoids were collected or reared during the course of our studies of the Aculeate Hymenoptera of Puerto Rico

The ponerine, Anochetus kempft Brown, is a cryptic nocturnal ant, widely distributed in Puerto Rico and the Virgin Islands. It is found in various habitats ranging from dry forest to rain forest. Males and the ergatoid queens are here described and illustrated for the first time. Mature colonies contain about 100 workers and may include several queens. We have observed males flying every month except March. In artificial nests we have observed that workers execute excess queens and males which do not depart from the nest within a short time following eclosion. These executions appear to be...

In this study, we quantify the abundance and composition of the litter fauna in dry and wet tropical forests and north- and south-facing subalpine forests. We used the same litter species contained in litterbags across study sites to standardize for substrate conditions, and a single method of fauna extraction from the litter (Tullgren method). Fauna densities were calculated per gram of dry litter. We found a higher density of total litter fauna and a higher taxonomic diversity in the tropical wet forest (80 individuals and 4 orders per g of dry litter and) as compared to the tropical dry...

Se consideró por primera vez incluir las especies de árboles tropicales en Silvics of North America en el 1980, cuando el Servicio Forestal del Departamento de Agricultura de los Estados Unidos de Norteamérica decidió poner al día el Manual de Agricultura 271, Silvics of forest trees of the United States. Diez años más tarde el Manual de Agricultura 654 se publicó con 20 descripciones silviculturales de especies de árboles tropicales. Los científicos en Puerto Rico trabajando en lo que para ese tiempo se conocía como el Instituto de Dasonomía Tropical, decidieron darse la tarea de desarroll...

Stream water chemistry responds substantially to watershed disturbances, but hurricane effects have not been extensively investigated in tropical regions. This study presents a long-term (2.5±11 y) weekly record of stream water chemistry on eight forested watersheds (catchment basins) in the Luquillo Mountains of Puerto Rico. This includes a period before and at least 2 y after the disturbance caused by the 1989 Hurricane Hugo. Nitrate, potassium and ammonium concentrations increased after the hurricane and remained elevated for up to 2 y. Sulphate, chloride, sodium, magnesium and calcium...