Understanding the relationship between great apes and their habitat is essential for the development of successful conservation strategies. The chimpanzee Pan troglodytes ellioti is endemic to ...Nigeria and Cameroon, and occupies an ecologically diverse range of habitats from forests to forest-savannah mosaic in Mbam-Djerem National Park (MDNP) in Cameroon. The habitat variation in chimpanzees is poorly understood in MDNP which provides an excellent opportunity to assess ecological factors that shape the abundance and distribution patterns of P. t. ellioti over a small geographic scale.
We counted 249 nests along 132 km of transects in total. Of these, 119 nests along 68 km occurred in dense forest and 130 nests along 64 km in forest-savannah mosaic. Chimpanzee density was 0.88 95% CI (0.55-1.41) individuals/km
in the dense forest and 0.59 95% CI (0.19-1.76) in the forest-savannah mosaic. Nest abundance varied with vegetation type and was higher in areas with dense canopy cover, steeper slopes and relatively higher altitudes.
Our estimates of chimpanzee densities were lower than reported in other studied populations in the range of the Nigeria-Cameroon chimpanzee. However, we found that habitat features, slope and altitude likely play a role in shaping patterns of chimpanzee nesting ecology. Further studies need to be focused on nest decay rates and phenology of useful plants in order to model chimpanzee abundance and distribution in Mbam-Djerem National Park.
Efforts to designate priority areas for conservation have had a long history, with most modern initiatives focused on either designating areas important for biodiversity or those least impacted by ...direct human disturbance. Ecologically intact ecosystems are becoming increasingly limited on the planet, making their identification and conservation an important priority. Intact forest landscapes (IFL) are defined as forests that are mainly free of significant anthropogenic degradation and at least 500 km2 in size. Here we define a new metric, the Last of the Wild in each Ecoregion (LWE), as a preliminary scoping of the most intact parts of each ecoregion. IFL and LWE are approaches among a broad family of techniques to mapping ecological integrity at the global scale. Although both implicitly include species integrity as a dimension of intactness, this is inferred rather than directly measured. We assessed whether IFL or LWE areas were better at capturing species where they are most abundant using species distribution data for a set of forest species for which range-wide data were available and human activity limits the range. We found that IFL and LWE methods identified areas where species we assessed are either absent or at too low an abundance to be ecologically functional. As such many IFL/LWE polygons did not have intact fauna. We also show that 54.7% of the terrestrial realm (excluding Antarctica) has at least one species recorded as extinct and that two thirds of IFL/LWE areas overlap with areas where species have gone extinct in the past 500 years. The results show that even within the most remote areas, serious faunal loss has taken place at many localities so direct species survey work is also needed to confirm faunal intactness.
Over the last two millennia, and at an accelerating pace, the African elephant (Loxodonta spp. Lin.) has been threatened by human activities across its range.1–7 We investigate the correlates of ...elephant home range sizes across diverse biomes. Annual and 16-day elliptical time density home ranges8 were calculated by using GPS tracking data collected from 229 African savannah and forest elephants (L. africana and L. cyclotis, respectively) between 1998 and 2013 at 19 sites representing bushveld, savannah, Sahel, and forest biomes. Our analysis considered the relationship between home range area and sex, species, vegetation productivity, tree cover, surface temperature, rainfall, water, slope, aggregate human influence, and protected area use. Irrespective of these environmental conditions, long-term annual ranges were overwhelmingly affected by human influence and protected area use. Only over shorter, 16-day periods did environmental factors, particularly water availability and vegetation productivity, become important in explaining space use. Our work highlights the degree to which the human footprint and existing protected areas now constrain the distribution of the world’s largest terrestrial mammal.9,10 A habitat suitability model, created by evaluating every square kilometer of Africa, predicts that 18,169,219 km2 would be suitable as elephant habitat—62% of the continent. The current elephant distribution covers just 17% of this potential range of which 57.4% falls outside protected areas. To stem the continued extirpation and to secure the elephants’ future, effective and expanded protected areas and improved capacity for coexistence across unprotected range are essential.
•229 African elephants were tracked across forest, Sahel, savanna, and bushveld sites•Protected areas and the human footprint both constrain elephant range size•62% of the African continent is potential elephant habit, of which elephants use 17%•85% of potential elephant habitat lies outside current protected areas
Using GPS tracking from 229 African elephants across Sahel, forest, savannah, and bushveld sites, Wall et al. show that protected areas and the human footprint are the main factors affecting elephant range size. A habitat suitability model shows that 62% of Africa is potentially habitable, but elephants occupy just 17% of the 18 million square kilometers.
The Critically Endangered western lowland gorilla Gorilla gorilla gorilla is found at high density in the swamp forests of Lac Télé Community Reserve, northern Republic of Congo. Preliminary surveys ...for apes on the Reserve periphery in the 1990s indicated that this area may also contain high densities of apes and we wished to verify this. Using distance sampling methodology we surveyed 1,029 km2 of the south-eastern Reserve periphery including Raphia swamp forests. We recorded 1,021 ape nests along 21 2-km transects. Results indicated that ape density estimated from nest group density, excluding old and very old Raphia nests (which may decay slowly), was very high: 6.81 weaned apes km-2 (95% confidence interval 3.93–11.84). Gorillas built most of the nests recorded: their density was estimated at 5.25 individuals km-2 (2.70–10.19). Most nests were constructed in Raphia swamp forest despite it covering only 25% of the study area. These are among the highest recorded densities of apes in Central Africa but, as nest decay rates in swamps are unstudied, we also estimated densities based on hypothetically slow nest decay rates and published data from other habitats. Gorilla densities may be linked to availability of monocotyledons as food and the natural protection from hunting offered by Raphia swamps. Gorilla density in swamp forest is spatially and temporally variable and surveys are required to estimate ape populations elsewhere in this habitat. Most Raphia swamps in Congo are unprotected, including the periphery of Lac Télé Community Reserve; protection and management are required to assure their continued availability for apes.
Poaching has devastated forest elephant populations (Loxodonta cyclotis), and their habitat is dramatically changing. The long-term effects of poaching and other anthropogenic threats have been well ...studied in savannah elephants (Loxodonta africana), but the impacts of these changes for Central Africa's forest elephants have not been discussed. We examined potential repercussions of these threats and the related consequences for forest elephants in Central Africa by summarizing the lessons learned from savannah elephants and small forest elephant populations in West Africa. Forest elephant social organization is less known than the social organization of savannah elephants, but the close evolutionary history of these species suggests that they will respond to anthropogenic threats in broadly similar ways. The loss of older, experienced individuals in an elephant population disrupts ecological, social, and population parameters. Severe reduction of elephant abundance within Central Africa's forests can alter plant communities and ecosystem functions. Poaching, habitat alterations, and human population increase are probably compressing forest elephants into protected areas and increasing human-elephant conflict, which negatively affects their conservation. We encourage conservationists to look beyond documenting forest elephant population decline and address the causes of these declines when developing conversation strategies. We suggest assessing the effectiveness of the existing protected-area networks for landscape connectivity in light of current industrial and infrastructure development. Longitudinal assessments of the effects of landscape changes on forest elephant sociality and behavior are also needed. Finally, lessons learned from West African elephant population loss and habitat fragmentation should be used to inform strategies for land-use planning and managing human-elephant interactions. Las Consecuencias de la Caza Furtiva y el Cambio Antropogénico para los Elefantes del Bosque Resumen La caza furtiva ha devastado a las poblaciones de los elefantes del bosque (Loxodonta cyclotis) y su hábitat está cambiando dramáticamente. Los efectos a largo plazo de la caza furtiva y de otras amenazas antropogénicas han sido estudiadas profundamente en los elefantes de la sabana (Loxodonta africana), pero el impacto de estos cambios sobre los elefantes del bosque del centro de África no ha sido discutido. Examinamos las repercusiones potenciales de estas amenazas y las consecuencias relacionadas para los elefantes del bosque del centro de África al resumir las lecciones aprendidas de los elefantes de la sabana y las pequeñas poblaciones de elefantes del bosque en el oeste de África. La organización social de los elefantes del bosque es menos conocida que la organización social de los elefantes de la sabana, pero la cercanía de la historia evolutiva de estas dos especies sugiere que responderán a las amenazas antropogénicas de maneras generalmente similares. La pérdida de individuos más viejos y con mayor experiencia en una población de elefantes causa disrupciones en los parámetros ecológicos, sociales y poblacionales. La reducción severa de la abundancia de elefantes dentro de los bosques del centro de África puede alterar a las comunidades vegetales y a las funciones del ecosistema. La caza furtiva, las alteraciones del hábitat y el incremento de la población humana probablemente estén orillando a las poblaciones de los elefantes del bosque hacia las áreas protegidas, e incrementado el conflicto humano-elefante, el cual afecta negativamente a su conservación. Alentamos a los conservacionistas a ver más allá de la documentación de la declinación de la población de elefantes del bosque y a enfocarse en las causas de esta declinación cuando se desarrollen estrategias de conservación. Sugerimos que se evalúe la efectividad de las redes existentes de áreas protegidas para la conectividad de paisajes de frente al desarrollo actual de industrias e infraestructuras. También es necesario realizar evaluaciones longitudinales de los efectos del cambio de paisaje sobre la organización social y el comportamiento de los elefantes del bosque. Finalmente, las lecciones aprendidas de la pérdida de poblaciones de elefantes del oeste de África y de la fragmentación del hábitat deberían usarse para informar a las estrategias de planeación del uso de suelo y de manejo de interacciones humano-elefante.
Environmental Issues in Central Africa Abernethy, Katharine; Maisels, Fiona; White, Lee J.T
Annual review of environment and resources,
10/2016, Letnik:
41, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The Central African forests, the planet's second largest rainforest block, are key to global environmental health. They influence climate change through their crucial role in carbon sinking and ...storage, affect weather patterns across Africa, and safeguard unique species and biodiverse communities. Their fate is important to everyone, not just today's inhabitants. The forests cover seven countries, and the differing socioeconomic histories and trajectories of these nations determine divergent fates for people, trees, and wildlife across the region. We review current knowledge of how the Central African forests have been shaped by climate and human activity within the region and assess how they may evolve under future climate change, population growth, and the Anthropocene race for wealth and energy. We highlight three different environmental trajectories for the countries of the region, identify key current regional issues that have an international dimension, and highlight five new points of future concern.
More than a quarter of the world's tropical forests are exploited for timber
. Logging impacts biodiversity in these ecosystems, primarily through the creation of forest roads that facilitate hunting ...for wildlife over extensive areas. Forest management certification schemes such as the Forest Stewardship Council (FSC) are expected to mitigate impacts on biodiversity, but so far very little is known about the effectiveness of FSC certification because of research design challenges, predominantly limited sample sizes
. Here we provide this evidence by using 1.3 million camera-trap photos of 55 mammal species in 14 logging concessions in western equatorial Africa. We observed higher mammal encounter rates in FSC-certified than in non-FSC logging concessions. The effect was most pronounced for species weighing more than 10 kg and for species of high conservation priority such as the critically endangered forest elephant and western lowland gorilla. Across the whole mammal community, non-FSC concessions contained proportionally more rodents and other small species than did FSC-certified concessions. The first priority for species protection should be to maintain unlogged forests with effective law enforcement, but for logged forests our findings provide convincing data that FSC-certified forest management is less damaging to the mammal community than is non-FSC forest management. This study provides strong evidence that FSC-certified forest management or equivalently stringent requirements and controlling mechanisms should become the norm for timber extraction to avoid half-empty forests dominated by rodents and other small species.
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