Forest Disturbance (forest + disturbance)

Distribution by Scientific Domains
Distribution within Life Sciences

Selected Abstracts

Applying climatically associated species pools to the modelling of compositional change in tropical montane forests

GLOBAL ECOLOGY, Issue 2 2008
Duncan J. Golicher
ABSTRACT Aim, Predictive species distribution modelling is a useful tool for extracting the maximum amount of information from biological collections and floristic inventories. However, in many tropical regions records are only available from a small number of sites. This can limit the application of predictive modelling, particularly in the case of rare and endangered species. We aim to address this problem by developing a methodology for defining and mapping species pools associated with climatic variables in order to investigate potential species turnover and regional species loss under climate change scenarios combined with anthropogenic disturbance. Location, The study covered an area of 6800 km2 in the highlands of Chiapas, southern Mexico. Methods, We derived climatically associated species pools from floristic inventory data using multivariate analysis combined with spatially explicit discriminant analysis. We then produced predictive maps of the distribution of tree species pools using data derived from 451 inventory plots. After validating the predictive power of potential distributions against an independent historical data set consisting of 3105 botanical collections, we investigated potential changes in the distribution of tree species resulting from forest disturbance and climate change. Results, Two species pools, associated with moist and cool climatic conditions, were identified as being particularly threatened by both climate change and ongoing anthropogenic disturbance. A change in climate consistent with low-emission scenarios of general circulation models was shown to be sufficient to cause major changes in equilibrium forest composition within 50 years. The same species pools were also found to be suffering the fastest current rates of deforestation and internal forest disturbance. Disturbance and deforestation, in combination with climate change, threaten the regional distributions of five tree species listed as endangered by the IUCN. These include the endemic species Magnolia sharpii Miranda and Wimmeria montana Lundell. Eleven vulnerable species and 34 species requiring late successional conditions for their regeneration could also be threatened. Main conclusions, Climatically associated species pools can be derived from floristic inventory data available for tropical regions using methods based on multivariate analysis even when data limitations prevent effective application of individual species modelling. Potential consequences of climate change and anthropogenic disturbance on the species diversity of montane tropical forests in our study region are clearly demonstrated by the method. [source]

The integration of ecological risk assessment and structured decision making into watershed management

Dan W Ohlson
Abstract Watershed management processes continue to call for more science and improved decision making that take into account the full range of stakeholder perspectives. Increasingly, the core principles of ecological risk assessment (i.e., the development and use of assessment endpoints and conceptual models, conducting exposure and effects analysis) are being incorporated and adapted in innovative ways to meet the call for more science. Similarly, innovative approaches to adapting decision analysis tools and methods for incorporating stakeholder concerns in complex natural resource management decisions are being increasingly applied. Here, we present an example of the integration of ecological risk assessment with decision analysis in the development of a watershed management plan for the Greater Vancouver Water District in British Columbia, Canada. Assessment endpoints were developed, ecological inventory data were collected, and watershed models were developed to characterize the existing and future condition of 3 watersheds in terms of the potential risks to water quality. Stressors to water quality include sedimentation processes (landslides, streambank erosion) and forest disturbance (wildfire, major insect or disease outbreak). Three landscape-level risk management alternatives were developed to reflect different degrees of management intervention. Each alternative was evaluated under different scenarios and analyzed by explicitly examining value-based trade-offs among water quality, environmental, financial, and social endpoints. The objective of this paper is to demonstrate how the integration of ecological risk assessment and decision analysis approaches can support decision makers in watershed management. [source]

Effects of plant structure on butterfly diversity in Mt. Marsabit Forest , northern Kenya

Nyamweya N. Humpden
Abstract Butterflies, like most forest dependent animals are good ecological indicators of the health of the forests they dwell. For example, butterfly species richness decreases after a forest disturbance and fragmentation but a few species may subsequently invade the forest fragment and boost the species richness. Studies were conducted to determine the effects of human activity and seasonal changes on butterfly species in the affected new habitats. Results showed that both seasonal and habitat changes significantly affect the butterfly abundance (P = 0.0001). Similarly, there was significant correlation between plant diversity and butterfly diversity in wet season (r = 0.854) and dry season (r = 0.855). The significance of these studies as a useful tool for sustainable forest use and conservation is discussed. Résumé Les papillons, comme la plupart des animaux dépendant de la forêt, sont de bons indicateurs écologiques de la santé des forêts qu'ils occupent. Par exemple, la richesse d'une forêt en espèces de papillons diminue suite à sa perturbation et à sa fragmentation, mais quelques espèces peuvent par la suite envahir la forêt et booster la richesse en espèces. On a réalisé des études pour déterminer les effets des activités humaines et des changements saisonniers sur les espèces de papillons dans des habitats récemment touchés. Les résultats ont montré que tant les changements saisonniers que les changements de l'habitat affectent significativement l'abondance des papillons (P = 0.0001). De même, il y avait une corrélation significative entre la diversité des plantes et celle des papillons en saison des pluies (r = 0.854) et en saison sèche (r = 0.855). L'on discute de l'importance de ces études comme outil utile à l'utilisation et à la conservation de la forêt. [source]

Forest fragmentation and primates' survival status in non-reserved forests of the ,Kampala area', Uganda

D. BarangaArticle first published online: 17 AUG 200
Abstract Previous primate studies have concentrated on the effects of forest disturbance on primate populations residing mainly in natural forest reserves. The present study was conducted in 20 non-reserved forest patches in the ,Kampala area', a forest-savanna-agricultural mosaic, to investigate the effects of forest fragmentation on the distribution and survival status of arboreal primates in the patches. Mpanga Forest Reserve, as the nearest to the forest patches, was used as a control. Primate census data revealed that the black-and-white colobus (Colobus guereza) was restricted in its distribution while redtail monkeys (Cercopithecus ascanius schmidti) were cosmopolitan. There was no significant relationship between forest patch size and red-tail population size, number of groups and group density decreased. Of the trees sampled, 70% were food species while 30% were nonfood species. Basal area of food tree species significantly increased with forest patch size (R2 = 0.5885) but its relationship with red-tail population size and group density (B = ,0.42784, R2 = 0.18305, P >,0.05) was not significant. [source]

Dating the introduction of cereal cultivation to the British Isles: early palaeoecological evidence from the Isle of Man

James B. Innes
Abstract The adoption of cereal cultivation is a key benchmark in the transition from Mesolithic hunter,gatherer foraging to Neolithic farming economies, but the nature, timing and ecological,cultural context of the earliest cereal use in the British Isles and northwest Europe is still uncertain. We present AMS radiocarbon dating and fine-resolution pollen evidence from the Isle of Man for cereal growing in the latter stages of a distinct episode of forest disturbance at almost 6000,yr,BP (uncalibrated). The coherent ecological structure of this phase at the fine resolution level suggests that it records cereal cultivation well before the Ulmus decline, rather than wild grass pollen grains. This example is one of a cluster of early dates for cereal-type pollen near the start of the sixth millenium BP, including several around the Irish Sea, which indicate that the introduction of cereal agriculture probably occurred as early in the central British Isles as in the northern European plain. This early cereal phase is followed later by a probable phase of pre- Ulmus decline pastoral activity. We also report Mesolithic age woodland disturbance around 7000,yr,BP (uncalibrated) and the first radiocarbon dates for mid-Holocene forest history of the Isle of Man. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Ranging behavior and habitat selection of terrestrial insectivorous birds in north-east Tanzania: implications for corridor design in the Eastern Arc Mountains

W. D. Newmark
Abstract Understanding the ranging behavior and habitat selection of understory tropical birds is important for corridor design and enhancing functional connectivity in fragmented tropical landscapes. Here we report on the ranging behavior and habitat selection of three terrestrial insectivorous bird species, the spot-throat Modulatrix stictigula, Usambara thrush Turdus roehli and orange ground thrush Zoothera gurneyi, in the East (EUM) and West (WUM) Usambara Mountains in north-east Tanzania. Based on 5945 locations and 3676 bird radio-tracking hours conducted between 2001 and 2008 at four study sites in the EUM and WUM, we determined that the 95% kernel home range and 50% kernel core range for the spot-throat, Usambara thrush, and orange ground thrush are similar yet large (aggregate mean home range=10.3±1.1 ha; aggregate mean core range 1.5±0.4 ha); that these species are adverse to crossing non-forested openings , no bird was recorded over the course of the study to cross a non-forested opening >15 m; and that the most extinction-prone species in our study system, the spot-throat and Usambara thrush, preferentially used slightly disturbed and primary forest, respectively. These results indicate that maintaining continuous forest cover and minimizing forest disturbance in corridors in the Eastern Arc Mountains is important for enhancing their habitat suitability for these species. [source]

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

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]

Smaller and more numerous harvesting gaps emulate natural forest disturbances: a biodiversity test case using rove beetles (Coleoptera, Staphylinidae)

Jan Klimaszewski
ABSTRACT Aim To evaluate changes in the abundance, species richness and community composition of rove beetles (Coleoptera, Staphylinidae) in response to three configurations of experimental gap cuts and to the effects of ground scarification in early succession yellow birch-dominated boreal forest. In each experimental treatment, total forest removed was held constant (35% removal by partial cutting with a concomitant decrease in gap size) but the total number of gaps was increased (two, four and eight gaps, respectively), resulting in an experimental increase in the total amount of ,edge' within each stand. Location Early succession yellow birch-dominated forests, Quebec, Canada. Methods Pitfall traps, ANOVA, MIXED procedure in sas®, post hoc Tukey's adjustment, rarefaction estimates, sum-of-squares and distance-based multivariate regression trees (ssMRT, dbMRT). Results Estimates of species richness using rarefaction were highest in clearcut and two-gap treatments, decreased in smaller and more numerous gaps and were significantly higher in scarified areas than in unscarified areas. ANOVA indicated a significant impact of harvesting on the overall standardized catch. Post hoc Tukey's tests indicated that the total catch of all rove beetles was significantly higher in uncut forests than in the treated areas. Both sum-of-squares and distance-based multivariate regression trees indicated that community structure of rove beetles differed among treatments. Assemblages were grouped into (a) control plots, (b) four- and eight-gap treatments and (c) two-gap and clearcut treatments. Main conclusions Rove beetle composition responded significantly to increasing gap size. Composition among intermediate and small-sized gap treatments (four- and eight-gap treatments) was more similar to uncut control forests than were larger gap treatments (two-gap) and clearcuts. Effects of scarification were nested within the harvested treatments. When the total area of forest removed is held constant, smaller, more numerous gaps are more similar to uncut control stands than to larger gaps and falls more closely within the natural forest heterogeneity. [source]