Treesearch

The vertical extent of waveforms collected by the Geoscience Laser Altimeter System (onboard ICESat - the Ice, Cloud, and land Elevation Satellite) increases as a function of terrain slope and footprint size (the area on the ground that is illuminated by the laser). Over sloped terrain, returns from both canopy and ground surfaces can occur at the same elevation. As a result, the height of the waveform (waveform extent) is insufficient to make estimates of tree height on sloped terrain, and algorithms are needed that are capable of retrieving information about terrain slope from the...

Microsatellites were used to evaluate the mating system of the remaining trees in a logged population of Swietenia macrophylla, a highly valuable and threatened hardwood species, in the Brazilian Amazon. A total of 25 open pollinated progeny arrays of 16 individuals, with their mother trees, were genotyped using eight highly polymorphic microsatellite loci. Genotypic data analysis from the progeny arrays showed that 373 out of the 400 seedlings (93.25%) were unambiguously the result of outcrossed matings and that the remaining 6.75% had genotypes consistent with self-fertilisation....

Comprehensive analysis of land morphology is essential to supporting a wide range environmental studies. We developed a landforms model that identifies eleven landform units for Puerto Rico based on parameters of land position and slope. The model is capable of extracting operational information in a simple way and is adaptable to different environments and objectives. The implementation of the landforms model for land cover change analysis represents an advanced step towards understanding the expansion of urban areas and forest cover in Puerto Rico between 1977 and 1994. Expansion of...

Primary tropical forests are renowned for their high biodiversity and carbon storage, and considerable research has documented both species and carbon losses with deforestation and agricultural land uses. Economic drivers are now leading to the abandonment of agricultural lands, and the area in secondary forests is increasing. We know little about how long it takes for these ecosystems to achieve the structural and compositional characteristics of primary forests. In this study, we examine changes in plant species composition and aboveground biomass during eight decades of tropical...

Temperate headwater streams with closed canopies rely on inputs of terrestrially derived organic matter to provide the major energy basis for their food webs. Microbial colonization, or conditioning, makes leaf litter more nutritional and palatable to stream detritivores, but few studies have investigated the relative importance of litter source to macroshredders in tropical streams. We determined the source (terrestrial, aquatic, or aerial), quantity, and species composition of allochthonous inputs into the Quebrada Prieta, a tropical headwater stream in Puerto Rico, as a first step...

Three groups of Native Americans, the Ciboneys, Arawaks, and Caribs, reached the Virgin Islands in pre-Columbian times. Since their discovery by Columbus in 1493, the Virgin Islands have been held or governed by Spain, Britain, the Netherlands, France, the Knights of Malta, Denmark, and the United States. They have also been held or used by groups ranging from estate owners and trading companies to pirates and squatters. European settlement of St. Croix, which began about 1625, resulted in the gradual replacement of that island's native forest with agricultural estates. Estate Thomas, on...

A comprehensive biodiversity study of the Scolytidae (Coleoptera) of Puerto Rico, USA has been underway for several years. Seventy-one species are now recorded from the island. One new genus, Allothenemus, is described with Allothenemus minutus new species, as the type species. An additional 13 new species are described: Chramesus atlanticus, Scolytodes puertoricensis, S. atlanticus, Pseudothysanoes magnispinatus, Hypothenemus amplissimus, H. concavifrons, Trischidias puertoricensis, Xyleborus atlanticus, Theoborus puertoricensis, Coptoborus bellus, Xyleborinus insulosus, Pityophthorus...

Dry forest environments limit the number of species that can survive there. Antillean dry forests have low floristic diversity and stature, high density of small and medium-sized trees, and are among the least conserved of the tropical forests. Their canopies are smooth with no emergent trees and have high species dominance. Antillean dry forests occur mostly on limestone substrate, exposing them to more water stress and nutrient limitations than other dry forests. They also experience periodic hurricanes and anthropogenic disturbances. Many of the attributes that allow plants to survive...