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PubMed1997

Molecular microbial diversity in soils from eastern Amazonia: evidence for unusual microorganisms and microbial population shifts associated with deforestation.

Although the Amazon Basin is well known for its diversity of flora and fauna, this report represents the first description of the microbial diversity in Amazonian soils involving a culture-independent approach. Among the 100 sequences of genes coding for small-subunit rRNA obtained by PCR amplification with universal small-subunit rRNA primers, 98 were bacterial and 2 were archaeal. No duplicate sequences were found, and none of the sequences had been previously described. Eighteen percent of the bacterial sequences could not be classified in any known bacterial kingdom. Two sequences may represent a unique branch between the vast majority of bacteria and the deeply branching, predominantly thermophilic bacteria. Five sequences formed a clade that may represent a novel group within the class Proteobacteria. In addition, rRNA intergenic spacer analysis was used to show significant microbial population differences between a mature forest soil and an adjacent pasture soil.

Bacteria↗
PubMed1996

Dynamics of malaria transmission in forested and deforested regions of Mandla District, central India (Madhya Pradesh).

A longitudinal malaria study was undertaken in 1990-91 in 2 adjacent ecological zones in central India: villages in forest and villages away from the forest. The prevalence of Anopheles species varied widely between the 2 ecological settings. In the villages in forest, Anopheles culicifacies and An. fluviatilis were mainly exophilic, whereas in the villages away from forest, An. culicifacies was predominantly endophilic and An. fluviatilis was equally prevalent both indoors and outdoors. The seasonal patterns of malaria transmission were also different between the 2 zones. Plasmodium falciparum was the dominant parasite species in the villages in forest, whereas malaria infection was mainly due to Plasmodium vivax in the villages away from forest. The annual parasite incidence was high in the villages in forest. The failure to control malaria in forested areas is rooted in the terrain and a variety of poorly understood sociological factors.

Animals↗
PubMed2001

Jamaica's disappearing forests: physical and human aspects.

Jamaica is a small island that is losing its forest cover at a rapid rate. Due to the dependency of its largely poor population on the many services and functions its forests provide, this loss threatens to have substantial socioeconomic and ecological consequences for the country. Despite these basic facts, the problem of Jamaican deforestation has received very little attention from the scientific community. This article presents results of an island-wide, satellite-based study of forest change for Jamaica for the period 1987-1992, which was supplemented by a field trip to the island in 1999 to assess the overall accuracy of the estimate. Landsat MSS images, which are available only up until 1992, have proved to be an invaluable and cost-effective resource for mapping forest change in the tropics, particularly in large areas. A supervised classification indicates that Jamaica experienced an average annual deforestation rate of 3.9% for this period, a figure higher than existing estimates based on partial ground surveys but lower than the FAO's 1990 Tropical Forest Assessment of 5.3% for 1981-1990. Deforestation estimates for Jamaica's 14 parishes are also presented, based on the integration of satellite-derived forest classification maps with a parish administrative boundaries map of the island in a GIS. A correlation analysis between parish deforestation estimates and socioeconomic and land use/quality indicators derived from official sources suggests that deforestation is occurring most rapidly in highly populated areas possessing large numbers of small farmers who live and work under resource-poor conditions. By providing a sense of the magnitude of and main forest loss hotspots, it is hoped that these national and subnational level forest estimates will draw scientific attention to the problem of deforestation on the island. In addition, the socioeconomic analysis may provide policy-makers and planners with some sense of the relative contribution of underlying driving process in this deforestation as a first step toward the creation of effective social programs to combat the problem.

Agriculture↗
PubMed2005

Effects of microclimatic changes caused by land use and land cover on duration of gonotrophic cycles of Anopheles gambiae (Diptera: Culicidae) in western Kenya highlands.

Studies were carried out at a malaria epidemic-prone highland site in western Kenya to determine the effects of deforestation-caused microclimate change on the duration of the gonotrophic cycle of the malaria vector Anopheles gambiae Giles. Gonotrophic cycle duration was measured using field-collected F1 A. gambiae females. Average ambient temperature in the deforested area of Kakamega (elevation 1,430-1,580 m above sea level), western Kenya, was 0.5 degrees C higher than that of the forested area over a 10-mo period. During the dry season, deforested areas showed an increased mean indoor temperature of 1.8 degrees C, and a shortened duration of the mosquitoes' first and second gonotrophic cycles, by 1.7 d (59%) and 0.9 d (43%). During the rainy season, the average indoor temperature of houses located in the deforested area was 1.2 degrees C higher than in houses in the forested area. The duration of the first and second gonotrophic cycles was shortened by 1.5 d (17%) and 1.4 d (27%), respectively, in the deforested highland site. A shorter mosquito gonotrophic cycle implies increased daily biting frequency and thus increased vectorial capacity. Together with evidence that deforestation reduced A. gambiae larva-to-adult developmental time and increased larval and adult survivorship, this study suggests that deforestation can further enhance malaria transmission potential in the highlands through increased indoor temperature and shortened gonotrophic cycle durations of A. gambiae mosquitoes.

Animals↗
PubMed2004

High mate and site fidelity in cunningham's skinks (Egernia cunninghami) in natural and fragmented habitat.

While habitat alteration has considerable potential to disrupt important within-population processes, such as mating and kin structure, via changed patterns of dispersal, this has rarely been tested. We are investigating the impact of anthropogenic habitat alteration on the population biology of the rock-dwelling Australian lizard Egernia cunninghami on the Central Tablelands of New South Wales, Australia, by comparing deforested and adjacent naturally vegetated areas. The novel analyses in this paper, and its companion, build on previous work by adding a new replicate site, more loci and more individuals. The additional microsatellite loci yield sufficient power for parentage analysis and the sociobiological inferences that flow from it. Genetic and capture-mark-recapture techniques were used to investigate mate and site fidelity and associated kin structure. Analyses of the mating system and philopatry using 10 microsatellite loci showed high levels of site fidelity by parents and their offspring in natural and deforested habitats. Parentage assignment revealed few individuals with multiple breeding partners within seasons and fidelity of pairs across two or more breeding seasons was typical. Despite reduced dispersal, increased group sizes and significant, dramatic increases in relatedness among individuals within rock outcrops in deforested areas, no significant differences between deforested and natural areas were evident in the degree of multiple mating or philopatry of breeding partners within and across seasons. With the exception that there was a significantly higher proportion of unmated males in the deforested area, the social and mating structure of this species has so far been surprisingly robust to substantial perturbation of dispersal and relatedness structure. Nonetheless, approximately 10-fold elevation of mean pairwise relatedness in the deforested areas has great potential to increase inbred matings, which is investigated in the companion paper.

Animals↗
PubMed2002

An ecosystem report on the Panama Canal: monitoring the status of the forest communities and the watershed.

In 1996, the Smithsonian Tropical Research Institute and the Republic of Panama's Environmental Authority, with support from the United States Agency for International Development, undertook a comprehensive program to monitor the ecosystem of the Panama Canal watershed. The goals were to establish baseline indicators for the integrity of forest communities and rivers. Based on satellite image classification and ground surveys, the 2790 km2 watershed had 1570 km2 of forest in 1997, 1080 km2 of which was in national parks and nature monuments. Most of the 490 km2 of forest not currently in protected areas lies along the west bank of the Canal, and its management status after the year 2000 turnover of the Canal from the U.S. to Panama remains uncertain. In forest plots designed to monitor forest diversity and change, a total of 963 woody plant species were identified and mapped. We estimate there are a total of 850-1000 woody species in forests of the Canal corridor. Forests of the wetter upper reaches of the watershed are distinct in species composition from the Canal corridor, and have considerably higher diversity and many unknown species. These remote areas are extensively forested, poorly explored, and harbor an estimated 1400-2200 woody species. Vertebrate monitoring programs were also initiated, focusing on species threatened by hunting and forest fragmentation. Large mammals are heavily hunted in most forests of Canal corridor, and there was clear evidence that mammal density is greatly reduced in hunted areas and that this affects seed predation and dispersal. The human population of the watershed was 113 000 in 1990, and grew by nearly 4% per year from 1980 to 1990. Much of this growth was in a small region of the watershed on the outskirts of Panama City, but even rural areas, including villages near and within national parks, grew by 2% per year. There is no sewage treatment in the watershed, and many towns have no trash collection, thus streams near large towns are heavily polluted. Analyses of sediment loads in rivers throughout the watershed did not indicate that erosion has been increasing as a result of deforestation, rather, erosion seems to be driven largely by total rainfall and heavy rainfall events that cause landslides. Still, models suggest that large-scale deforestation would increase landslide frequency, and failure to detect increases in erosion could be due to the gradual deforestation rate and the short time period over which data are available. A study of runoff showed deforestation increased the amount of water from rainfall that passed directly into streams. As a result, dry season flow was reduced in a deforested catchment relative to a forested one. Currently, the Panama Canal watershed has extensive forest areas and streams relatively unaffected by humans. But impacts of hunting and pollution near towns are clear, and the burgeoning population will exacerbate these impacts in the next few decades. Changes in policies regarding forest protection and pollution control are necessary.

Animals↗
PubMed1997

Seeing the forests for the more than the trees.

Assessing the health effects of deforestation is difficult because of the rate at which the world's forests are disappearing. From 1990 to 1995 alone, the world lost a total area of forest cover nearly twice the size of Italy. Deforestation, which is caused by human population growth and encroachment, clearance for agricultural production, and the growing worldwide demand for wood products, has been linked with effects ranging from local changes in climatic and disease patterns to global climate change and biodiversity loss. Deforestation is responsible for about 25% of net annual releases of carbon dioxide into the atmosphere and also lessens the amount of forest available to absorb greenhouse gas emissions. Deforestation also causes a tremendous loss of biodiversity worldwide. It is estimated that over the next 50 years deforestation will rank as the single greatest cause of species loss.

Communicable Diseases↗
PubMed2000

Comparative phytosociology of tree sinusiae between contiguous forests in different stages of succession.

The Baturité Mountain Range, located in the State of Ceará (BRA), displays on its highest levels a vegetation viewed as a disjunction from the Atlantic Forest in the East of Brazil. Among the various attributes associated with this vegetation, the abundance of water resources and a high biodiversity have a more outstanding relevance. However, in view of the current accelerated deforestation process, those attributes may be threatened in a near future. Therefore, the present work is a comparative study with its focus on vegetal community organization (tree sinusiae) and the floristic similarity and the phytodiversity of two areas in different successive stages, preserved and deforested 24 years ago. The aim of that intent was to obtain information that could essentially shed light on the deforestation effects on tree vegetation and which could suggest scientific support regarding urgent projects of habitat reconstruction. The methodology used folowed the model utilized for rain forest, i.e. consisting of a random distribution of 10 x 20 m plots surveying the living woody species with DBH >/= 5 cm. The results obtained suggest that a possible new physiognomy type is emerging on the Baturite Mountain Range because of deforestation. The Myrtaceae and Mimosaceae families were the ones that contributed most significantly to species richness, being the most outstanding for Areas 1 and 2, respectively. The deforestation which occurred in Area 2 eliminated 28 species and gave birth to a current densely distinct floristic composition.

Brazil↗