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Disturbed Forest (disturbed + forest)

Distribution by Scientific Domains

Life Sciences	87%

Selected Abstracts

Effects of Conversion of Dry Tropical Forest to Agricultural Mosaic on Herpetofaunal Assemblages

CONSERVATION BIOLOGY, Issue 2 2008
IRERI SUAZO-ORTUÑO
atributos de vulnerabilidad; bosque tropical seco; ensambles herpetofaunísticos; modificación del hábitat; mosaico agrícola Abstract:,We explored the impact of forest conversion to agricultural mosaic on anuran, lizard, snake, and turtle assemblages of Neotropical dry forests. Over 2 years, we sampled 6 small watersheds on the west coast of Mexico, 3 conserved and 3 disturbed. The disturbed watersheds were characterized by a mosaic of pastures and cultivated fields (corn, beans, squash) intermingled with patches of different successional stages of dry forest. In each watershed, we conducted 11 diurnal and nocturnal time-constrained searches in 10 randomly established plots. We considered vulnerability traits of species in relation to habitat modification. Eighteen anuran, 18 lizard, 23 snake, and 3 turtle species were recorded. Thirty-six species (58%) occurred in both forest conditions, and 14 (22%) and 12 species (19%) occurred only in the conserved and disturbed sites, respectively. Assemblages responded differently to disturbance. Species richness, diversity, and abundance of lizards were higher in disturbed forests. Anuran diversity and species richness were lower in disturbed forest but abundance was similar in both forest conditions. Diversity, richness, and abundance of turtles were lower in disturbed forest. The structure and composition of snake assemblages did not differ between forest conditions. We considered species disturbance sensitive if their abundance was significantly less in disturbed areas. Four anuran (22%), 2 lizard (11%), and 3 turtle (100%) species were sensitive to disturbance. No snake species was sensitive. The decline in abundance of disturbance-sensitive species was associated with the reduction of forest canopy cover, woody stem cover, roots, and litter-layer ground cover. Anuran species with small body size and direct embryonic development were especially sensitive to forest disturbance. An important goal for the conservation of herpetofauna should be the determination of species traits associated with extinction or persistence in agricultural mosaics. Resumen:,Exploramos el impacto de la conversión de bosques a mosaico agrícola sobre ensambles de lagartijas, serpientes y tortugas de bosques Neotropicales secos. Durante 2 años muestreamos 6 cuencas pequeñas, 3 conservadas y 3 perturbadas, en la costa occidental de México. Las cuencas perturbadas se caracterizaron por un mosaico de pastizales y campos cultivados (maíz, frijol, calabaza) entremezclados con parches de bosque seco en diferentes etapas sucesionales. En cada cuenca, realizamos 11 búsquedas diurnas y nocturnas en 10 parcelas establecidas aleatoriamente. Consideramos los atributos de vulnerabilidad de especies en relación con la modificación del hábitat. Registramos 18 especies de lagartijas, 23 de serpientes y 3 de tortugas. Treinta y seis especies (58%) ocurrieron en ambas condiciones de bosque, y 14 (22%) y 12 (19%) especies solo ocurrieron en los sitios conservados y perturbados, respectivamente. Los ensambles respondieron a la perturbación de manera diferente. La riqueza de especies, la diversidad y la abundancia de lagartijas fueron mayores en los bosques perturbados. La diversidad y riqueza de especies de anuros fueron menores en el bosque perturbado pero la abundancia fue similar en ambas condiciones de bosque. La diversidad, riqueza de especies y abundancia de tortugas fueron menores en el bosque perturbado. La estructura y la composición de los ensambles de serpientes no difirieron entre condiciones de bosque. Consideramos que las especies eran sensibles a la perturbación si su abundancia fue significativamente menor en las áreas perturbadas. Cuatro (22%) especies de anuros, 2 (11%) de lagartijas y 3 (100%) de tortugas fueron sensibles a la perturbación. Ninguna especie de serpiente fue sensible. La declinación en la abundancia de especies sensibles a la perturbación se asoció con la reducción en la cobertura del dosel, de tallos leñosos, raíces y hojarasca. Las especies de anuros de cuerpo pequeño y desarrollo embrionario directo fueron especialmente sensibles a la perturbación del bosque. La determinación de atributos de las especies asociadas con su extinción o persistencia en mosaicos agrícolas debería ser una meta importante para la conservación de la herpetofauna. [source]

Links between habitat degradation, and social group size, ranging, fecundity, and parasite prevalence in the Tana River mangabey (Cercocebus galeritus)

AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 3 2009
David N.M. Mbora
Abstract We investigated the effects of anthropogenic habitat degradation on group size, ranging, fecundity, and parasite dynamics in four groups of the Tana River mangabey (Cercocebus galeritus). Two groups occupied a forest disturbed by human activities, while the other two occupied a forest with no human disturbance. We predicted that the groups in the disturbed forest would be smaller, travel longer distances daily, and have larger home ranges due to low food tree abundance. Consequently, these groups would have lower fecundity and higher parasite prevalence and richness (number of parasite species). We measured the abundance of food trees and anthropogenic activity in the forests, the groups' daily travel distances and home range sizes, and censused social groups over 12 months. We also analyzed fecal samples for gastrointestinal parasites from three of the groups. The disturbed forest had a lower abundance of food trees, and groups in this forest traveled longer distances, had larger home range sizes, were smaller, and had lower fecundity. The groups in the disturbed forest had higher, although not statistically significant, parasite prevalence and richness. This study contributes to a better understanding of how anthropogenic habitat change influences fecundity and parasite infections in primates. Our results also emphasize the strong influence of habitat quality in determining daily travel distance and home range size in primates. Am J Phys Anthropol, 2009. © 2009 Wiley-Liss, Inc. [source]

Chimpanzee responses to researchers in a disturbed forest,farm mosaic at Bulindi, western Uganda

AMERICAN JOURNAL OF PRIMATOLOGY, Issue 10 2010
Matthew R. McLennan
Abstract We describe the behavior of a previously unstudied community of wild chimpanzees during opportunistic encounters with researchers in an unprotected forest,farm mosaic at Bulindi, Uganda. Data were collected during 115 encounters between May 2006 and January 2008. Individual responses were recorded during the first minute of visual contact. The most common responses were "ignore" for arboreal chimpanzees and "monitor" for terrestrial individuals. Chimpanzees rarely responded with "flight". Adult males were seen disproportionately often relative to adult females, and accounted for 90% of individual responses recorded for terrestrial animals. Entire encounters were also categorized based on the predominant response of the chimpanzee party to researcher proximity. The most frequent encounter type was "ignore" (36%), followed by "monitor" (21%), "intimidation" (18%) and "stealthy retreat" (18%). "Intimidation" encounters occurred when chimpanzees were contacted in dense forest where visibility was low, provoking intense alarm and agitation. Adult males occasionally acted together to repel researchers through aggressive mobbing and pursuit. Chimpanzee behavior during encounters reflects the familiar yet frequently agonistic relationship between apes and local people at Bulindi. The chimpanzees are not hunted but experience high levels of harassment from villagers. Human-directed aggression by chimpanzees may represent a strategy to accommodate regular disruptions to foraging effort arising from competitive encounters with people both in and outside forest. Average encounter duration and proportion of encounters categorized as "ignore" increased over time, whereas "intimidation" encounters decreased, indicating some habituation occurred during the study. Ecotourism aimed at promoting tolerance of wildlife through local revenue generation is one possible strategy for conserving great apes on public or private land. However, the data imply that habituating chimpanzees for viewing-based ecotourism in heavily human-dominated landscapes, such as Bulindi, is ill-advised since a loss of fear of humans could lead to increased negative interactions with local people. Am. J. Primatol. Am. J. Primatol. 72:907,918, 2010. © 2010 Wiley-Liss, Inc. [source]

Habitat-specific ranging patterns of Dian's tarsiers (Tarsius dianae) as revealed by radiotracking

AMERICAN JOURNAL OF PRIMATOLOGY, Issue 2 2006
Stefan Merker
Abstract Dian's tarsier Tarsius dianae, one of the smallest primates on earth, is endemic to the central regions of Sulawesi, Indonesia. To evaluate the effects of increasing land use by humans on the ranging patterns of this nocturnal insect hunter, four study plots along a gradient of anthropogenic disturbance were selected for this study. In these plots, 71 tarsiers were captured with mist nets, and 30 of these were fitted with 3.9 g radiotransmitters and subsequently tracked over the course of 2 weeks per animal. The average home ranges were 1.1,1.8 ha in size, with the smallest ranges in slightly disturbed habitat and the largest ranges in a heavily disturbed plantation. These findings coincide with different estimates of insect abundance in the study plots. Nightly travel distances were smallest in undisturbed old-growth forest and slightly increased along a gradient of human disturbance. The tarsiers were most active shortly after dusk and just before dawn. The results of this comprehensive radiotracking study on tarsiers show that T. dianae adapts its ranging behavior to the degree and type of human land use. Integrated data on home range size and travel distance indicate that slightly disturbed forest is as favorable to these animals as undisturbed habitat. However, with increasing anthropogenic effects, the living conditions of the tarsiers appear to deteriorate, resulting in the necessity for larger home and night ranges. The results of this study provide an important tool for directing conservation efforts targeted at the survival of this primate in central Sulawesi. Am. J. Primatol. 68:111,125, 2006. © 2006 Wiley-Liss, Inc. [source]

Invasion by Rattus rattus into native coastal forests of south-eastern Australia: are native small mammals at risk?

AUSTRAL ECOLOGY, Issue 4 2009
VICKI L. STOKES
Abstract The black rat, Rattus rattus, is an alien rodent in Australian ecosystems where niche overlap with native small mammals may lead to competition for resources and displacement of native species. In coastal habitats surrounding Jervis Bay in south-eastern Australia, R. rattus co-occurs with the native bush rat, Rattus fuscipes, and brown antechinus, Antechinus stuartii. Relative distributions and abundances, and fine-scale space use suggest invasive and native rodents compete for use of space and habitat. Such competitive interactions were not evident between R. rattus and native A. stuartii, which was negatively influenced more by disturbance to habitat. Differences in rodent communities between spatially separate forests forming the northern and southern peninsulas of Jervis Bay potentially reflect symmetrical competition and differences in competitive outcomes. In southern forests, R. rattus was largely restricted to patches of disturbed forest associated with campgrounds. Competitive interference by native rodent populations inhabiting surrounding intact forests may have so far limited R. rattus colonization of these areas. In northern forests, R. rattus was the predominant rodent irrespective of disturbance, while populations of R. fuscipes were unusually low seemingly due to poor juvenile recruitment. Native individuals avoided areas frequented by adult R. rattus and given that species did not partition use of microhabitats, R. rattus most likely precluded R. fuscipes from suitable habitat and in doing so limited native populations. We discuss how natural disturbance of habitat and human activity have potentially facilitated successful invasion by R. rattus of the northern forests. Studies that manipulate rodent populations are required to support these interpretations of observed patterns. [source]

Effects of Conversion of Dry Tropical Forest to Agricultural Mosaic on Herpetofaunal Assemblages

SOIL EROSION AND SEDIMENT YIELD PREDICTION ACCURACY USING WEPP,

JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 2 2004
John M. Laflen
ABSTRACT: The objectives of this paper are to discuss expectations for the Water Erosion Prediction Project (WEPP) accuracy, to review published studies related to WEPP goodness of fit, and to evaluate these in the context of expectations for WEPP's goodness of fit. WEPP model erosion predictions have been compared in numerous studies to observed values for soil loss and sediment delivery from cropland plots, forest roads, irrigated lands and small watersheds. A number of different techniques for evaluating WEPP have been used, including one recently developed where the ability of WEPP to accurately predict soil erosion can be compared to the accuracy of replicated plots to predict soil erosion. In one study involving 1,594 years of data from runoff plots, WEPP performed similarly to the Universal Soil Loss Erosion (USLE) technology, indicating that WEPP has met the criteria of results being "at least as good with respect to observed data and known relationships as those from the USLE," particularly when the USLE technology was developed using relationships derived from that data set, and using soil erodibility values measured on those plots using data sets from the same period of record. In many cases, WEPP performed as well as could be expected, based on comparisons with the variability in replicate data sets. One major finding has been that soil erodibility values calculated using the technology in WEPP for rainfall conditions may not be suitable for furrow irrigated conditions. WEPP was found to represent the major storms that account for high percentages of soil loss quite well,a single storm application that the USLE technology is unsuitable for,and WEPP has performed well for disturbed forests and forest roads. WEPP has been able to reflect the extremes of soil loss, being quite responsive to the wide differences in cropping, tillage, and other forms of management, one of the requirements for WEPP validation. WEPP was also found to perform well on a wide range of small watersheds, an area where USLE technology cannot be used. [source]

Mate-locating behaviour, habitat-use, and flight morphology relative to rainforest disturbance in an Afrotropical butterfly

BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2009
DRIES BONTE
To cope with environmental constraints, organisms can show variation in phenotype, either by genetic adaptation or phenotypic plasticity. These patterns are especially pronounced in ecosystems that are under anthropogenic influence. Due to human-induced disturbances such as logging and deforestation, tropical forests comprise such a system. To date, most studies have dealt with ecological responses at the community level relative to forest disturbance or degradation. However, the evolutionary consequences of tropical forest deterioration on behaviour and functional morphology have received far less attention compared to temporal regions. From a resource-point of view, light conditions are essential for heliotherms such as butterflies. Because degradation of tropical cloud forests in the Taita Hills (Kenya) is very pronounced, the present study tested whether this induced changes in mate-location strategies, habitat-use, and functional flight morphology in a forest butterfly, Salamis parhassus. According to predictions from temperate regions, it was hypothesized that the species would change its mate location strategy from perching to patrolling in more disturbed forests, that this higher mobility results in a faster occupancy of light gaps, and that it accords with a higher wing loading within populations from undisturbed forests. These hypotheses were confirmed by field surveys and experiments. The present study demonstrates that degradation of tropical forests does not only affect communities (e.g. species richness), but also the behaviour and functional morphology of individual species. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 96, 830,839. [source]