Consistent patterns of common species across tropical tree communities

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 locations1,2,3,4,5,6 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 histories7, 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

Gallery forests versus bosquets: conservation of natural fragments at Lope National Park in central Gabon

Human-induced forest fragmentation has been relatively well-studied, however, we know very little about the role of natural fragmentation in sustaining rare or marginal species that could have been lost if the advancement of continuous forest had not been controlled. Between February 2001 and January 2003, we conducted a study on characteristics of natural forest fragments in the mosaic of forests and savannas in the north of Lopé National Park in Central Gabon. We surveyed 61 vegetation plots (0.08 ha each) and compared vegetation characteristics of isolated forest fragments (bosquets) with those of gallery forests. Both shared 39% of all 251 species inventoried. Gallery forests contained 45% plant species on their own, while 16% were encountered only in bosquets. Therefore, bosquets were found to be valuable component of the Lopé landscape worth protecting. In addition, the Shannon-Wienner diversity index (H′) was higher for bosquets neighbouring gallery forests or continuous forests regardless of their sizes because seeds of new plant species were easily dispersed in these bosquets. To protect these gallery forests and bosquets, one of the traditional conservation tools - a controlled savanna burning - should still be used to prevent forest fragments from being engulfed by the expanding continuous forest

Contribution and stability of forest-derived soil organic carbon during woody encroachment in a tropical savanna. A case study in Gabon

In this study, we quantified the contribution of forest-derived carbon (FDC) to the soil organic C (SOC) pool along a natural succession from savanna (S) to mixed Marantaceae forest (MMF) in the Lopè National Park, Gabon. Four 1-ha plots, corresponding to different stages along the natural succession, were used to determine the SOC stock and soil C isotope composition (δ13C) to derive the FDC contribution in different soil layers down to 1 m depth. Besides, to investigate changes in SOC stability, we determined the 14C concentration of SOC to 30 cm depth and derived turnover time (TT). Results indicated that SOC increased only at the end of the succession in the MMF stage, which stored 46% more SOC (41 Mg C ha−1) in the 0–30 cm depth than the S stage (28.8 Mg C ha−1). The FDC contribution increased along forest succession affecting mainly the top layers of the initial successional stages to 15 cm depth and reaching 70 cm depth in the MMF stage. The TT suggests a small increase in stability in the 0–5 cm layer from S (146 years) to MMF (157 years) stages. Below 5 cm, the increase in stability was high, suggesting that FDC can remain in soils for a much longer time than savanna-derived C. In conclusion, the natural succession toward Marantaceae forests can positively impact climate change resulting in large SOC stocks, which can be removed from the atmosphere and stored for a much longer time in forest soils compared to savanna soils. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature

The conservation significance of the proposed Mbaere-Bodingue national park, Central African Republic, with special emphasis on its primate community

WOS:000227153600015International audienceThe proposed Mbaere-Bodingue National Park ( 872 km(2)) is located in the southwestern part of the Central African Republic and consists of terra firma rain forests and seasonally flooded forests. We assessed the conservation significance of this site using data on wildlife and habitat conditions collected during a comprehensive primate survey. Scores were attributed to a system of variables and sub-variables to assess the conservation value of the proposed park at the national level. We identified a total of 10 diurnal primate species ( eight monkeys, two apes) and flooded forests were considered as a key habitat for primates as they hold a greater number of species than terra firma forests. We recorded the presence of 12 mammal species listed under the 2000 IUCN Red List of Threatened Species, including four classified as Endangered ( two Primates, one Proboscidae and one Insectivora). We found that the conservation value of the proposed park ranked second out of the 15 existing protected areas of the country. Primate abundance was found to be generally higher than in the nearby Dzanga-Ndoki National Park ( the sole other park located in the same vegetation unit), in particular for the species occurring in flooded forests. This highlights the fact that the proposed Mbaere-Bodingue National Park is an important area for the conservation of species associated with flooded forests, a habitat which is currently underrepresented in the national protected area system. Poaching pressure was identified as the main current threat to the integrity of the proposed park

Contribution and stability of forest-derived soil organic carbon during woody encroachment in a tropical savanna. A case study in Gabon

In this study, we quantified the contribution of forest-derived carbon (FDC) to the soil organic C (SOC) pool along a natural succession from savanna (S) to mixed Marantaceae forest (MMF) in the Lopè National Park, Gabon. Four 1-ha plots, corresponding to different stages along the natural succession, were used to determine the SOC stock and soil C isotope composition (δ13C) to derive the FDC contribution in different soil layers down to 1 m depth. Besides, to investigate changes in SOC stability, we determined the 14C concentration of SOC to 30 cm depth and derived turnover time (TT). Results indicated that SOC increased only at the end of the succession in the MMF stage, which stored 46% more SOC (41 Mg C ha−1) in the 0–30 cm depth than the S stage (28.8 Mg C ha−1). The FDC contribution increased along forest succession affecting mainly the top layers of the initial successional stages to 15 cm depth and reaching 70 cm depth in the MMF stage. The TT suggests a small increase in stability in the 0–5 cm layer from S (146 years) to MMF (157 years) stages. Below 5 cm, the increase in stability was high, suggesting that FDC can remain in soils for a much longer time than savanna-derived C. In conclusion, the natural succession toward Marantaceae forests can positively impact climate change resulting in large SOC stocks, which can be removed from the atmosphere and stored for a much longer time in forest soils compared to savanna soils. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature

Forest elephant group composition, frugivory and coastal use in the Réserve de Faune du Petit Loango, Gabon

Results of a 16-month study of forest elephant (Loxodonta africana cyclotis Matschie) group size and composition, coastal use and frugivory are presented from the Réserve de Faune du Petit Loango, Gabon (now the Parc National de Loango). Mean forest elephant group size was 2.2 (n = 140) including solitary animals, and 3.1 excluding solitaries. Elephants consumed fruits of at least 49 species, and of the 220 elephant dungpiles examined, 185 (84.1%) contained seeds and 203 (92.3%) contained the remains of fruits (seeds and/or pulp). The mean number of seed species per dungpile (±SD) was 2.01 ± 1.49, and the mean number of fruit species was 2.28 ± 1.43. Elephants used the coastal habitat more during warmer months, and during the afternoon than the morning. It is hypothesized that coastal habitat use is related to sodium intake through consumption of salt-coated vegetation