Tropical forests store 40-50% of terrestrial vegetation carbon 1 . Spatial variations in aboveground live tree biomass carbon (AGC) stocks remain poorly understood, in particular in tropical montane forests 2 . Owing to climatic and soil changes with increasing elevation 3 , AGC stocks are lower in tropical montane compared to lowland forests 2 . Here we assemble and analyse a dataset of structurally intact old-growth forests (AfriMont) spanning 44 montane sites in 12 African countries. We find that montane sites in the AfriMont plot network have a mean AGC-stock of 149.4 Mg C ha -1 (95% CI 137.1-164.2), comparable to lowland forests in the African Tropical Rainforest Observation Network 4 and about 70 per cent and 32 per cent higher than averages from plot networks in montane 2,5,6 and lowland 7 forests in the Neotropics, respectively. Notably, our results are two-thirds higher than the IPCC default values for these forests in Africa 8 . We find that the low stem density and high abundance of large trees of African lowland forests 4 is mirrored in the montane forests sampled. This carbon store is endangered: we estimate that 0.8 million ha of old-growth African montane forest have been lost since 2000. We provide country-specific montane forest AGC stock estimates modelled from our plot network to help guide forest conservation and reforestation interventions. Our findings highlight the need for conserving these biodiverse 9,10 and carbon-rich ecosystems.
Two separate subfamilies of Plio‐Pleistocene African pigs (suids) consecutively evolved hypsodont and horizodont molars with flat occlusal surfaces, commonly interpreted as an adaptive trait to a grazing diet, similar to that of the present warthogs (Phacochoerus spp.). To investigate this in detail, we studied the 3D‐dental topography of fossil specimens from the Turkana Basin, using geographic information systems‐based methods. To establish baselines for interpretation of the Turkana Basin suids, topography of third molars of extant suids with known diets were analyzed: grazing warthog (Phacochoerus africanus), herbivorous mixed‐feeder forest hog (Hylochoerus meinertzhageni), omnivorous generalist wild boar (Sus scrofa), omnivorous fruit and tuber eater bush pig (Potamochoerus spp.), and omnivorous fruit eater babirusa (Babyrousa spp.) In addition, we analyzed supposedly browsing Miocene suids, Listriodon spp. The same topographic measures were applied to Plio‐Pleistocene specimens from the Turkana Basin, Kenya: Notochoerus euilus, Notochoerus scotti, Kolpochoerus heseloni, and Metridiochoerus andrewsi. With some differences between techniques, 3D‐dental topography analysis of extant suid molars mostly predicts the dietary differences between the species correctly. The grazing P. africanus differs from both the omnivorous suids and the herbivorous mixed‐feeder H. meinertzhageni in all except one metrics. The omnivorous mostly tropical suids, Potamochoerus and Babyrousa, primarily differ from the generalist, S. scrofa, in the orientation patch count analysis, showing higher occlusal complexity in the latter. Although, there might be significant gaps between the morphological changes and the ecological changes, we conclude that based on comparison of dental topography with the present‐day suids, N. scotti and M. andrewsi were most likely highly specialized grazers, while N. euilus and K. heseloni retained more of their ancestral, omnivorous heritage, but consumed grasses more than the extant omnivorous suids. Research highlights Dental topography can predict different diets in present‐day wild pigs. The Plio‐Pleistocene pigs in the Turkana Basin had dental topography mostly similar to extant grazing warthog, although some species also had resemblances to omnivorous forest pigs.
Afromontane tropical forests maintain high biodiversity and provide valuable ecosystem services, such as carbon sequestration. The spatial distribution of aboveground biomass (AGB) in forest-agriculture landscape mosaics is highly variable and controlled both by physical and human factors. In this study, the objectives were (1) to generate a map of AGB for the Taita Hills, in Kenya, based on field measurements and airborne laser scanning (ALS), and (2) to examine determinants of AGB using geospatial data and statistical modelling. The study area is located in the northernmost part of the Eastern Arc Mountains, with an elevation range of approximately 600-2200 m. The field measurements were carried out in 215 plots in 2013-2015 and ALS flights conducted in 2014-2015. Multiple linear regression was used for predicting AGB at a 30 m × 30 m resolution based on canopy cover and the 25th percentile height derived from ALS returns (R 2 = 0.88, RMSE = 52.9 Mg ha −1 ). Boosted regression trees (BRT) were used for examining the relationship between AGB and explanatory variables at a 250 m × 250 m resolution. According to the results, AGB patterns were controlled mainly by mean annual precipitation (MAP), the distribution of croplands and slope, which explained together 69.8% of the AGB variation. The highest AGB densities have been retained in the semi-natural vegetation in the higher elevations receiving more rainfall and in the steep slope, which is less suitable for agriculture. AGB was also relatively high in the eastern slopes as indicated by the strong interaction between slope and aspect. Furthermore, plantation forests, topographic position and the density of buildings had a minor influence on AGB. The findings demonstrate the utility of ALS-based AGB maps and BRT for describing AGB distributions across Afromontane landscapes, which is important for making sustainable land management decisions in the region.
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