Impacts of tropical forest disturbance on species vital rates

Tropical forests are experiencing enormous threats from deforestation and habitat degradation. Much knowledge of the impacts of these land-use changes on tropical species comes from studies examining patterns of richness and abundance. Demographic vital rates (survival, reproduction, and movement) can also be affected by land-use change in a way that increases species vulnerability to extirpation, but in many cases these impacts may not be manifested in short-term changes in abundance or species richness. We conducted a literature review to assess current knowledge and research effort concerning how land-use change affects species vital rates in tropical forest vertebrates. We found a general paucity of empirical research on demography across taxa and regions, with some biases toward mammals and birds and land-use transitions, including fragmentation and agriculture. There is also considerable between-species variation in demographic responses to land-use change, which could reflect trait-based differences in species sensitivity, complex context dependencies (e.g., between-region variation), or inconsistency in methods used in studies. Efforts to improve understanding of anthropogenic impacts on species demography are underway, but there is a need for increased research effort to fill knowledge gaps in understudied tropical regions and taxa. The lack of information on demographic impacts of anthropogenic disturbance makes it difficult to draw definite conclusions about the magnitude of threats to tropical ecosystems under anthropogenic pressures. Thus, determining conservation priorities and improving conservation effectiveness remains a challenge

Assessing Conservation Values: Biodiversity and Endemicity in Tropical Land Use Systems

Despite an increasing amount of data on the effects of tropical land use on continental forest fauna and flora, it is debatable whether the choice of the indicator variables allows for a proper evaluation of the role of modified habitats in mitigating the global biodiversity crisis. While many single-taxon studies have highlighted that species with narrow geographic ranges especially suffer from habitat modification, there is no multi-taxa study available which consistently focuses on geographic range composition of the studied indicator groups. We compiled geographic range data for 180 bird, 119 butterfly, 204 tree and 219 understorey plant species sampled along a gradient of habitat modification ranging from near-primary forest through young secondary forest and agroforestry systems to annual crops in the southwestern lowlands of Cameroon. We found very similar patterns of declining species richness with increasing habitat modification between taxon-specific groups of similar geographic range categories. At the 8 km2 spatial level, estimated richness of endemic species declined in all groups by 21% (birds) to 91% (trees) from forests to annual crops, while estimated richness of widespread species increased by +101% (trees) to +275% (understorey plants), or remained stable (- 2%, butterflies). Even traditional agroforestry systems lost estimated endemic species richness by - 18% (birds) to - 90% (understorey plants). Endemic species richness of one taxon explained between 37% and 57% of others (positive correlations) and taxon-specific richness in widespread species explained up to 76% of variation in richness of endemic species (negative correlations). The key implication of this study is that the range size aspect is fundamental in assessments of conservation value via species inventory data from modified habitats. The study also suggests that even ecologically friendly agricultural matrices may be of much lower value for tropical conservation than indicated by mere biodiversity value

Differences between Pygmy and Non-Pygmy hunting in Congo Basin forests

We use data on game harvest from 60 Pygmy and non-Pygmy settlements in the Congo Basin forests to examine whether hunting patterns and prey profiles differ between the two hunter groups. For each group, we calculate hunted animal numbers and biomass available per inhabitant, P, per year (harvest rates) and killed per hunter, H, per year (extraction rates). We assess the impact of hunting of both hunter groups from estimates of numbers and biomass of prey species killed per square kilometre, and by examining the proportion of hunted taxa of low, medium and high population growth rates as a measure of their vulnerability to overhunting. We then map harvested biomass (kg-1P-1Yr-1) of bushmeat by Pygmies and non-Pygmies throughout the Congo Basin. Hunting patterns differ between Pygmies and non-Pygmies; Pygmies take larger and different prey and non-Pygmies sell more for profit. We show that non-Pygmies have a potentially more severe impact on prey populations than Pygmies. This is because non-Pygmies hunt a wider range of species, and twice as many animals are taken per square kilometre. Moreover, in non-Pygmy settlements there was a larger proportion of game taken of low population growth rate. Our harvest map shows that the non-Pygmy population may be responsible for 27 times more animals harvested than the Pygmy population. Such differences indicate that the intense competition that may arise from the more widespread commercial hunting by non-Pygmies is a far more important constraint and source of conflict than are protected areas

The database of the PREDICTS (Projecting Responses of Ecological Diversity In Changing Terrestrial Systems) project

The PREDICTS project-Projecting Responses of Ecological Diversity In Changing Terrestrial Systems (www.predicts.org.uk)-has collated from published studies a large, reasonably representative database of comparable samples of biodiversity from multiple sites that differ in the nature or intensity of human impacts relating to land use. We have used this evidence base to develop global and regional statistical models of how local biodiversity responds to these measures. We describe and make freely available this 2016 release of the database, containing more than 3.2 million records sampled at over 26,000 locations and representing over 47,000 species. We outline how the database can help in answering a range of questions in ecology and conservation biology. To our knowledge, this is the largest and most geographically and taxonomically representative database of spatial comparisons of biodiversity that has been collated to date; it will be useful to researchers and international efforts wishing to model and understand the global status of biodiversity

The importance of agricultural areas for bird conservation in the Korup region, south-western Cameroon

Recent studies have shown that a relatively high number of individuals and species from the natural forest fauna can still be found in land use systems. To detect key parameters for population development and preconditions for long-term suitability of different land use systems for forest bird populations, we investigated patterns of species richness and abundance of understorey birds using mist-net data, in 24 study sites equally distributed over two types of natural and two types of agricultural habitats. We also assessed arthropod availability, nesting sites, parasite loads, and fault bars for trapped birds. We recorded high numbers of birds in all habitats but with a tendency for smaller species with increasing habitat modification. Our data support the idea that arthropod richness and density attract many understorey forest birds in agricultural areas but that environmental stress in these habitats might be high since numbers of bird species and individuals presenting fault bars were significantly higher in the agricultural matrix. In the Afrotropical context, the management of agricultural areas should consider preserving some aspects of natural habitats, and a fallow period of five to eight years, to avoid biodiversity loss

Social norms and cultural services - community belief system and use of wildlife products in the Northern periphery of the Korup National Park, South-West Cameroon

In many traditional societies, beliefs and taboos influence human behaviour towards the natural environment. Such beliefs and taboos are informal institutions where norms rather than official laws determine land use and nature protection in general and wildlife in particular. The present study on beliefs and taboos of the people of the northern periphery of the Korup National Park is an attempt to reveal how norms influence their relation to the environment. A total of 195 households were sampled through a household survey conducted in four villages. The results revealed that before the application of “modern” approaches for wildlife protection and management, the people relied on norms to establish a relationship with wildlife and nature. The enactment of the 1994 legislation on forest, wildlife and fisheries resulted in stiff resistance as it contradicts traditional norms. It was found that 57.4 % of the respondents still perceive wildlife as a resource that can never get extinct. Traditional norms had a differentiated impact especially on game protection. The study recommends that a wildlife benefiting code of beliefs and taboos is developed to provide a basis for establishing a synergy between park management laws and traditional belief/taboo systems that drive the management of wildlife

The relationship between the abundance of the Nigeria-Cameroon chimpanzee (Pan troglodytes ellioti) and its habitat: a conservation concern in Mbam-Djerem National Park, Cameroon

Background 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. Results 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/km2 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. Conclusions 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

Interleukin (IL)-2 and IL-12 responses to Chlamydia trachomatis infection in adolescents

Chlamydia trachomatis infects epithelial cells at the mucosal surface. While in vitro and animal studies have shown changes in mucosal T(H)1-associated cytokines in the presence of C. trachomatis infection and with its progression to the upper genital tract or clearance, in vivo cytokine responses to chlamydial infection in humans are not well understood. Using a quantitative enzyme-linked immunosorbent assay (ELISA), we examined the endocervical production of two T(H)1-associated cytokines, i.e. interleukin (IL)-2 and IL-12, in relation to C. trachomatis infection in adolescents. At a randomly selected visit for 396 females, median endocervical IL-2 levels were significantly lower (190 versus 283 pg/ml, P = 0·02) and median IL-12 levels significantly higher (307 versus 132 pg/ml, P < 0·001) in subjects testing positive versus negative for C. trachomatis. These divergent T(H)1-associated cytokine responses were: (1) confirmed in paired analyses of 96 individuals before and after infection within 6-month intervals, (2) reversible in 97 patients who cleared infection during consecutive visits, (3) not attributable to sociodemographic factors or other genital infections and (4) independent of common genetic variants at the IL2 and IL12B loci associated previously with differential gene expression. From these findings we infer that increased IL-12 and decreased IL-2, observed commonly during mucosal inflammation, are important features of mucosal immune defence against C. trachomatis infection