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Shifting cultivation is a predominant practice in the majority of tropical hilly tracts. Relatively few studies have examined forest recovery following shifting cultivation and we have reviewed these studies to identify and synthesize general recovery patterns. Most studies report that, although pioneer tree species recover relatively faster, woody biomass of mature forest trees recovers several decades after suspension of cultivation. Analysis of bird-species inventories in 10 studies revealed that up to 70% of mature forest birds may recover in successional sites and that species composition is about 55% similar to that in mature forests within 25 years. Results of mammal studies were likely to have been confounded by hunting effects and therefore the effect of time since suspension of cultivation and hunting impacts need to be investigated separately. As shown by a few studies, we conclude that community recovery can be expected to be accelerated when relatively large forest tracts adjoin a shifting cultivation landscape, in comparison with recovery in sites with shorter fallow cycles in the absence of contiguous forests, which act as sources for recolonization of fauna and vegetation.
Habitat loss and fragmentation are two of the main threats facing wildlife. The species at risk in small fragments are not a random subset of the original community. Understanding the biology behind the distinction between species at risk and more persistent species should help inform conservation efforts. We attempted to identify risky traits in a well-known taxon, the primates, by asking which traits distinguished taxa that differed in the size of the smallest fragment in which they were recorded. We assumed that taxa that could persist in smaller fragments were at less risk of extinction than those that needed larger fragments. The traits investigated are indicative of amount of habitat needed, reproductive rate, and specialization. We obtained from the literature information on the presence-absence of 68 primate species of 36 genera in forest fragments of less than 100 km2. Association between size of smallest fragment and biology was tested with regressions, Spearman correlations, two-sample t tests, and non-parametric Wilcoxon tests. We found no significant relationships between area of smallest fragment in which species or genera persisted and any of the biological parameters. We suggest that the most likely explanation for this unexpected finding is that the smallest fragments in which primates are currently studied are usually so small that all primate species in them are doomed in the long-term and therefore, no biological traits distinguish taxa at risk. The finding implies that conservation research and efforts should be directed at assessing the efficacy of forest fragments and small biological preserves in conserving primate species.
Forest managers and harvesters of non-timber forest products (NTFPs) need a tool for rapid measurement of the impact of their activities on seed dispersal and tree recruitment. Such a tool could be used for a prospective eco-label which would ensure regeneration. We propose, and have used a new rapid assessment protocol to sample and evaluate the impact of any anthropogenic disturbance on seed dispersal and seedling recruitment of hard-tegument fruit species enclosing large seeds. We set up this protocol in French Guiana for a large-seeded scatter-hoarded tree species, Carapa surinamensis (andiroba), at three different forest sites affected by a variety of anthropogenic pressures, such as hunting and logging. Over a limited time we assessed: 1) dispersal failure: from late May to mid-June, the proportion of seeds remaining undispersed was estimated by sampling the number of seeds, seedlings and fruit husks in 25-m2 subplots under the tree crown; 2) recruitment effectiveness: in September–October, seedlings were sampled on four 100-m2 plots located 5–15 m from the tree base around the tree crown. Altogether, 77 trees were sampled, some 1–2 hours being spent beneath each tree, during a total 4–6 weeks in the field for each dispersal and recruitment sampling. We showed that: 1) seed dispersal is affected by hunting, this being significantly marked in the coastal area, which faces major anthropogenic pressures; 2) logging treatments affect seed dispersal and regeneration, on the average. However, canopy gaps due to sylvicultural treatments raise the life expectancy of seedlings.
Tropical forests frequently experience the opening and closing of canopy gaps as part of their natural dynamics. When fragmented, the forests are also exposed to edges, which (at least in the lowlands) cause increased mortality on the fragment's periphery and—depending on the fragment size—also on the forest interior. Here we explore if the presence of edges increase the rate at which the canopy opens in a montane forest and if and how that interaction affects the vegetation composition and structure. At Las Cruces Biological Station (SW Costa Rica), we surveyed four 150 m edge-to-interior transects to evaluate changes in vegetation structure (stem density and basal area for all plants with DBH > 5 cm) and species richness and composition as a function of both distance to the edge and canopy openness. Edge proximity did not increase canopy openness. Canopy openness, however, did affect stem density, species richness, and composition. Consequently, heterogeneity in forest structure, diversity, or composition could not be attributed to indirect edge effects. Forest edges, however, had a direct effect on species composition, but with a negligible effect on species diversity and forest structure. Overall, these results reveal that the structure, diversity, and composition of tree communities in this tropical premontane forest fragment are more strongly influenced by canopy openness than by the proximity of edges.
Entre marzo y mayo de 2005, se realizó una evaluación ecológica rápida (EER) de los murciélagos presentes en el Parque Ecológico de Montelíbano. El estudio se realizó con un esfuerzo total de captura de 368 horas/red y comprendió los cinco biotopos presentes en el parque: humedal, rastrojo alto, pastizal, bosque húmedo tropical secundario y plantación forestal. Se registraron 17 especies de murciélagos agrupadas en 5 familias y 4 subfamilias. La familia mejor representada fue Phyllostomidae con 12 especies. Las espedes más abundantes fueron Artibeus jamaicensis, Uroderma bilobatum, Sturnira lilium y Carollia perspicillata. Se encontraron especies biotopo-específicas, tales como Phyllostomus elongatus y Saccopteryx bilineata en la plantación; Myotis sp., Glossophaga soricina, Sturnira ludovici y Noctilio leporinus en el humedal y Anoura sp. en el bosque. La composición de quirópteros del humedal es significativamente diferente (70% Jaccard, 0.72 bayes) con respecto a los demás biotopos. Los resultados muestran que las EERs de las comunidades de murciélagos, permiten identificar las zonas con prioridades de investigación en proyectos de conservación semi-urbana.
Fuel wood extraction for commercial fish smoking is the most pervasive threat to the sustainability of mangrove ecosystems in the Douala-Edea Wildlife Reserve (DEWR) of Cameroon and most West-Central African coastal states. The high rates of fuel-wood consumption are associated with fish smoking in this region and are chiefly the result of low fuel efficiency systems. In this study, we investigated the relative efficiency of two fish-smoking systems with respect to fuel wood consumption and time required for fish smoking in the DEWR. Using socio-economic and forest surveys in three villages, where mangrove wood is harvested and used, we established that the annual fuel-wood off-take was about 42,839m3. In addition, most of the wood is used for fish smoking in the Traditional Smoke System (TSS) method, which was assessed to be 70% less efficient than the Improved Smoke System (Eeyed/CWCS). The Eeyed/CWCS consumed on average 50% less wood than the TSS, and reduced fish-smoking time by up-to 65% relative to the TSS. This comparative advantage offers opportunities for reducing the incidence of smoke-related diseases in women and children–most of them involved in the smoking process—by reducing the time spent smoking fish and saving money from avoided additional wood consumption. However, these benefits can only be achieved through the successful introduction of the Eeyed/CWCS. This will require a broad range of sensitization, capacity enhancement, and further research on adapting the current model to local conditions of the area.
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