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Aim: Large trees [≥ 70 cm diameter at breast height (DBH)] contribute disproportionately to aboveground carbon stock (AGC) across the tropics but may be vulnerable to changing climate and human activities. Here we determine the distribution, drivers and threats to large trees and high carbon forest. Location: Central Africa. Time period: Current. Major taxa studied: Trees. Methods: Using Gabon's new National Resource Inventory of 104 field sites, AGC was calculated from 67,466 trees from 578 species and 97 genera. Power and Michaelis–Menten models assessed the contribution of large trees to AGC. Environmental and anthropogenic drivers of AGC, large trees, and stand variables were modelled using Akaike's information criterion (AIC) weights to calculate average regression coefficients for all p ossible models. Results: Mean AGC for trees ≥ 10 cm DBH in Gabonese forestlands was 141.7 Mg C/ha, with averages of 166.6, 171.3 and 96.6 Mg C/ha in old growth, concession and secondary forest. High carbon forests occurred where large trees are most abundant: 31% of AGC was stored in large trees (2.3% of all stems). Human activities largely drove variation in AGC and large trees, but climate and edaphic conditions also determined stand variables (basal area, tree height, wood density, stem density). AGC and large trees increased with distance from human settlements; AGC was 40% lower in secondary than primary and concession forests and 33% higher in protected than non‐managed areas. Main conclusions: AGC and large trees were negatively associated with human activities, highlighting the importance of forest management. Redefining large trees as ≥ 50 cm DBH (4.3% more stems) would account for 20% more AGC. This study demonstrates that protecting relatively undisturbed forests can be disproportionately effective in conserving carbon and suggests that including sustainable forestry in programs like reduced emissions for deforestation and forest degradation could maintain carbon dense forests in logging concessions that are a large proportion of remaining Central African forests. [ABSTRACT FROM AUTHOR]

Crop damage by forest elephants (Loxodonta africana cyclotis) and the resulting human-elephant conflict are issues of great concern for both the conservation of the species and the protection of rural livelihoods in Central Africa. Addressing these problems requires identifying the factors that facilitate or impede crop-raiding by forest elephants. Yet to date, the environmental or anthropogenic factors that influence the occurrence and intensity of crop-raiding by forest elephants are largely unknown. We used a multivariate approach to investigate conditions under which forest elephants raid some fields and not others in the buffer zone of Monts de Cristal National Park (MCNP), Gabon. We first interviewed 121 farmers from 11 villages situated within 10 km of MCNP regarding the occurrence of elephant crop-raiding of their fields. We then collected data on 39 explanatory variables to characterize the agricultural fields. Of these, the most important predictors of elephant raid occurrence of crop damage were presence of fruit trees, elephant deterrents (scarecrows, fire, wire string fences and empty barrels), and field topography. We secondly assessed the effect of stage of crop growth, presence of fruit trees, field topography and presence of elephant deterrents on crop-raiding occurrence and intensity by counting raids and measuring areas of crop damage every week in 17 plantations over 19 weeks in the most elephant-impacted zone of the study area. We found that fruit presence and stage of crop growth led to more intense damage to crops, whereas local deterrents did not inhibit raiding events and crop damage by elephants. We report a tradeoff between non-timber forest products (NTFP) services and crop-raiding by elephants. We show for the first time that steep topography impedes elephant damage to crops with no raids recorded in fields with surrounding slopes greater than 25%. We discuss whether farming on steep fields could be used as a strategy for mitigating crop-raiding to favor human-elephant coexistence and enhance elephant conservation. [ABSTRACT FROM AUTHOR]

Abstract: Poaching is rapidly extirpating African forest elephants (Loxodonta cyclotis) from most of their historical range, leaving vast areas of elephant‐free tropical forest. Elephants are ecological engineers that create and maintain forest habitat; thus, their loss will have large consequences for the composition and structure of Afrotropical forests. Through a comprehensive literature review, we evaluated the roles of forest elephants in seed dispersal, nutrient recycling, and herbivory and physical damage to predict the cascading ecological effects of their population declines. Loss of seed dispersal by elephants will favor tree species dispersed abiotically and by smaller dispersal agents, and tree species composition will depend on the downstream effects of changes in elephant nutrient cycling and browsing. Loss of trampling and herbivory of seedlings and saplings will result in high tree density with release from browsing pressures. Diminished seed dispersal by elephants and high stem density are likely to reduce the recruitment of large trees and thus increase homogeneity of forest structure and decrease carbon stocks. The loss of ecological services by forest elephants likely means Central African forests will be more like Neotropical forests, from which megafauna were extirpated thousands of years ago. Without intervention, as much as 96% of Central African forests will have modified species composition and structure as elephants are compressed into remaining protected areas. Stopping elephant poaching is an urgent first step to mitigating these effects, but long‐term conservation will require land‐use planning that incorporates elephant habitat into forested landscapes that are being rapidly transformed by industrial agriculture and logging. [ABSTRACT FROM AUTHOR]

Abstract: Overexploitation is one of the main pressures driving wildlife closer to extinction, yet broad‐scale data to evaluate species’ declines are limited. Using African pangolins (Family: Pholidota) as a case study, we demonstrate that collating local‐scale data can provide crucial information on regional trends in exploitation of threatened species to inform conservation actions and policy. We estimate that 0.4‐2.7 million pangolins are hunted annually in Central African forests. The number of pangolins hunted has increased by ∼150% and the proportion of pangolins of all vertebrates hunted increased from 0.04% to 1.83% over the past four decades. However, there were no trends in pangolins observed at markets, suggesting use of alternative supply chains. The price of giant (Smutsia gigantea) and arboreal (Phataginus sp.) pangolins in urban markets has increased 5.8 and 2.3 times respectively, mirroring trends in Asian pangolins. Efforts and resources are needed to increase law enforcement and population monitoring, and investigate linkages between subsistence hunting and illegal wildlife trade. [ABSTRACT FROM AUTHOR]

• Tree diversity and composition are affected by both hunting and logging. • Hunting and logging alter tree recruitment, especially near villages. • Combined, hunting and logging have a greater impact on tree communities. • Hunted and logged forests may contain lower carbon densities. Anthropogenic disturbances are changing the structure and composition of tropical forests worldwide. Multiple disturbances often occur simultaneously in forests. Hunting and logging, for example, are within-forest disturbances that impact vast areas of seemingly intact rainforests. Despite recent work on the individual effects of these disturbances, our understanding of how they interact to influence tree communities is still limited. In northern Republic of Congo, we explored the effects of hunting and logging on tree communities. Over an 8-year period, we monitored 12,552 tree stems (≥10 cm diameter-at-breast height) spread over 30 1-ha plots along a gradient of human disturbance to compare the tree diversity between hunted and logged forest, once-logged forest, and protected forest free of both disturbances. Tree density, species richness, and community composition were affected by both hunting and logging. Forest close to human settlements was richer, more heterogenous, and more dynamic in species composition across censuses. In hunted and logged forest, fast-growing secondary species with low shade tolerance replaced old growth species. Comparatively, the once-logged forest had the greatest stem density and intermediate species richness with an increased density of shade-bearing species over time. Both tree species spatial turnover and tree recruitment were greatly affected by proximity to human settlements. A shift towards abiotically dispersed trees and increasing seed predation by rodents near villages can partly explain the differences in tree recruitment across the forest types. The combination of hunting and logging seems to have a greater impact on tree communities than either single disturbance, especially with nearness to villages. [ABSTRACT FROM AUTHOR]

• Degraded, secondary forest in Gabon stores 123.8 Mg C ha−1 – higher than HCS. • Rubber can store similar carbon levels as secondary forest after a 30-year rotation. • Secondary forest has nearly double the time-averaged carbon stocks as rubber. • To reduce emissions, couple agriculture with planning, restoration, and set-asides. The development of agriculture on degraded lands is increasingly seen as a strategy to boost food availability and economic productivity while minimizing environmental degradation and loss of forests. To understand the effects of agricultural production on forest carbon, we quantify the aboveground carbon (AGC) of a degraded forest in northeast Gabon (the Olam Rubber Gabon concession) designated for development to a rubber plantation. Combining field measurements from 19 1-ha tree plots and aerial LiDAR, we estimate forest AGC stocks and emissions under four development scenarios: no development, 30-year rubber rotation, extended rubber rotation (replanting of plantation in stages at 30 and 40 years), and 30-year oil palm rotation. On average, the degraded forest in the study area stored 123.8 Mg C ha−1, a mean AGC lower than the Gabon average (141.6 Mg C ha−1) but substantially higher than the 75 Mg C ha−1 threshold recommended by the High Carbon Stock protocol. Converting secondary forest to plantation might incur high environmental opportunity costs from lost carbon sequestration through forest succession and growth. In this study, we estimate that a rubber plantation can sequester similar amounts of AGC as secondary forest by the end of a 30-year rotation; however, the time-averaged AGC of regenerating secondary forests under no development would be 184% higher than a mature rubber plantation with a 30-year rotation, 169% higher than an extended rubber rotation, and 512% higher than a 30-year oil palm rotation. When degraded forest is developed for agriculture, measures should be taken to avoid emissions and prolong carbon retention. We specifically estimate carbon retention from extended harvest rotations and conserving high carbon value areas as set-asides and highlight recommendations from the literature such as minimizing soil disturbance and creating rubber timber products (e.g. furniture). To minimize carbon emissions from agriculture, crop plantation area should be minimized at national and regional scales in highly forested countries, and new plantations should be coupled explicitly with effective forest restoration actions, through suitable regulation and planning, to mitigate or compensate for their climate and biodiversity impacts. [ABSTRACT FROM AUTHOR]

The article presents the author's views on his contributions to save the ecology of African jungles. He opines that a community reserve and a public-private partnership for conservation were among his conservation research and management projects in Congo. He comments on the conservation of tropical ecosystem.

Tropical areas are facing a bushmeat crisis involving the systematic over-exploitation of large-bodied mammals for both subsistence and commercial purposes. We hypothesize that because hunting generally originates from villages, it will create "halos of defaunation" where abundances of large mammals increase with distance away from villages. Whilst such patterns have been well characterized at the landscape scale, examining how defaunation halos vary between different villages has received considerably less attention. Forests immediately surrounding villages are of considerable importance to the people residing within them and the factors hypothesized to influence local defaunation halos (e.g. village size, hunting practices and access to local markets) may affect local livelihoods and the ecological integrity of nearby forests. To address this, we adopted a participatory approach to establish and monitor sixty transects across ten village-distance gradients (1-8 km) in Gabon. Trained paraecologists, recruited from local villages, walked each transect twice monthly to determine the encounter rates of medium and large mammals across the village distance gradient and monitored village-level bushmeat availability. We found that overall rates of mammal observation and estimated species richness were constant across the village-distance gradient, however the total number of individuals encountered and bushmeat biomass were lower close to villages – consistent with local depletion of wildlife. These general trends were underpinned by depleted mammal species diversity with increasing proximity to villages and a marked shift in mammal community composition: small, non-hunted species were encountered most frequently near villages, whereas large, hunted species were encountered most frequently away from villages. We found some evidence for inter-village variation in the strength and depth of defaunation halos, which may be driven in part by the village-level hunting intensity. Several of the key parameters identified in landscape-scale bushmeat studies did not detectably influence village-level defaunation (e.g. road or market distance). Despite the prevalence of bushmeat hunting in the region, the conservation value of forests immediately surrounding villages was demonstrated through the detection of large-bodied species of conservation concern (e.g. chimpanzee and gorilla) at a high proportion of survey locations. The compositional shifts in mammal communities detailed here will ultimately lead to the altered composition and diversity of forests around villages, with potential implications for human livelihoods, health and transmission of zoonotic disease. This research also demonstrates the effectiveness of engaging paraecologists to answer focused ecological questions - the first step in facilitating effective natural resource management by local communities. [ABSTRACT FROM AUTHOR]

Trees structure the Earth's most biodiverse ecosystem, tropical forests. The vast number of tree species presents a formidable challenge to understanding these forests, including their response to environmental change, as very little is known about most tropical tree species. A focus on the common species may circumvent this challenge. Here we investigate abundance patterns of common tree species using inventory data on 1,003,805 trees with trunk diameters of at least 10 cm across 1,568 locations 1-6 in closed-canopy, structurally intact old-growth tropical forests in Africa, Amazonia and Southeast Asia. We estimate that 2.2%, 2.2% and 2.3% of species comprise 50% of the tropical trees in these regions, respectively. Extrapolating across all closed-canopy tropical forests, we estimate that just 1,053 species comprise half of Earth's 800 billion tropical trees with trunk diameters of at least 10 cm. Despite differing biogeographic, climatic and anthropogenic histories 7 , we find notably consistent patterns of common species and species abundance distributions across the continents. This suggests that fundamental mechanisms of tree community assembly may apply to all tropical forests. Resampling analyses show that the most common species are likely to belong to a manageable list of known species, enabling targeted efforts to understand their ecology. Although they do not detract from the importance of rare species, our results open new opportunities to understand the world's most diverse forests, including modelling their response to environmental change, by focusing on the common species that constitute the majority of their trees., (© 2024. The Author(s).)

Structurally intact tropical forests sequestered about half of the global terrestrial carbon uptake over the 1990s and early 2000s, removing about 15 per cent of anthropogenic carbon dioxide emissions 1-3 . Climate-driven vegetation models typically predict that this tropical forest 'carbon sink' will continue for decades 4,5 . Here we assess trends in the carbon sink using 244 structurally intact African tropical forests spanning 11 countries, compare them with 321 published plots from Amazonia and investigate the underlying drivers of the trends. The carbon sink in live aboveground biomass in intact African tropical forests has been stable for the three decades to 2015, at 0.66 tonnes of carbon per hectare per year (95 per cent confidence interval 0.53-0.79), in contrast to the long-term decline in Amazonian forests 6 . Therefore the carbon sink responses of Earth's two largest expanses of tropical forest have diverged. The difference is largely driven by carbon losses from tree mortality, with no detectable multi-decadal trend in Africa and a long-term increase in Amazonia. Both continents show increasing tree growth, consistent with the expected net effect of rising atmospheric carbon dioxide and air temperature 7-9 . Despite the past stability of the African carbon sink, our most intensively monitored plots suggest a post-2010 increase in carbon losses, delayed compared to Amazonia, indicating asynchronous carbon sink saturation on the two continents. A statistical model including carbon dioxide, temperature, drought and forest dynamics accounts for the observed trends and indicates a long-term future decline in the African sink, whereas the Amazonian sink continues to weaken rapidly. Overall, the uptake of carbon into Earth's intact tropical forests peaked in the 1990s. Given that the global terrestrial carbon sink is increasing in size, independent observations indicating greater recent carbon uptake into the Northern Hemisphere landmass 10 reinforce our conclusion that the intact tropical forest carbon sink has already peaked. This saturation and ongoing decline of the tropical forest carbon sink has consequences for policies intended to stabilize Earth's climate.