Use of Ancient Sedimentary DNA as a Novel Conservation Tool for High‐Altitude Tropical Biodiversity

Conservation of biodiversity may in the future increasingly depend upon the availability of scientific information to set suitable restoration targets. In traditional paleoecology, sediment‐based pollen provides a means to define preanthropogenic impact conditions, but problems in establishing the exact provenance and ecologically meaningful levels of taxonomic resolution of the evidence are limiting. We explored the extent to which the use of sedimentary ancient DNA (sedaDNA) may complement pollen data in reconstructing past alpine environments in the tropics. We constructed a record of afro‐alpine plants retrieved from DNA preserved in sediment cores from 2 volcanic crater sites in the Albertine Rift, eastern Africa. The record extended well beyond the onset of substantial anthropogenic effects on tropical mountains. To ensure high‐quality taxonomic inference from the sedaDNA sequences, we built an extensive DNA reference library covering the majority of the afro‐alpine flora, by sequencing DNA from taxonomically verified specimens. Comparisons with pollen records from the same sediment cores showed that plant diversity recovered with sedaDNA improved vegetation reconstructions based on pollen records by revealing both additional taxa and providing increased taxonomic resolution. Furthermore, combining the 2 measures assisted in distinguishing vegetation change at different geographic scales; sedaDNA almost exclusively reflects local vegetation, whereas pollen can potentially originate from a wide area that in highlands in particular can span several ecozones. Our results suggest that sedaDNA may provide information on restoration targets and the nature and magnitude of human‐induced environmental changes, including in high conservation priority, biodiversity hotspots, where understanding of preanthropogenic impact (or reference) conditions is highly limited. Uso de ADN Sedimentario Antiguo como una Herramienta Novedosa de Conservación para la Biodiversidad Tropical de Grandes Altitudes     

Complementary Roles of Home Gardens and Exotic Tree Plantations as Alternative Habitats for Plants of the Ethiopian Montane Rainforest

Abstract:  Many tropical forests have been converted for agri- or silviculture or a combination of both (agroforestry). Conservation at a landscape scale requires an understanding of the distribution and abundance of native biodiversity in these converted natural ecosystems, of which the knowledge is especially poor for African agroecosystems. We compared species density and species composition of four plant groups (trees and shrubs, epiphytic vascular plants, mosses, and liverworts) among three arboreal land-use types in southwestern Ethiopia (montane rainforest fragments, shade-tree coffee home gardens, and exotic tree plantations). Species density was significantly higher in forests than in coffee home gardens for all plant groups and in exotic tree plantations for all groups except mosses. Home gardens had more vascular epiphytic species than plantations, whereas the reverse was true for mosses and liverworts. The species composition of the forest plots was sometimes more similar to home-garden plots than plantation plots and sometimes vice versa. Fifteen forest plots had, however, cumulatively more species than a random selection of 15 nonforest (coffee home garden and plantation) plots, even if the 2 plot types complemented each other in terms of habitats for forest plants. Tree plantations dominated by Eucalyptus had many small trees and shrubs in common with forests, whereas plantations with Cupressus were important substrates for forests mosses and liverworts. Our results illustrate the importance of undisturbed forests habitats for conservation of species at a landscape scale and that different human-made land-use types may complement each other in their capacity as additional habitats for forest species.     

Effects of Coffee Management on Deforestation Rates and Forest Integrity

Knowledge about how forest margins are utilized can be crucial for a general understanding of changes in forest cover, forest structure, and biodiversity across landscapes. We studied forest‐agriculture transitions in southwestern Ethiopia and hypothesized that the presence of coffee (Coffea arabica)decreases deforestation rates because of coffee's importance to local economies and its widespread occurrence in forests and forest margins. Using satellite images and elevation data, we compared changes in forest cover over 37 years (1973–2010) across elevations in 2 forest‐agriculture mosaic landscapes (1100 km² around Bonga and 3000 km² in Goma‐Gera). In the field in the Bonga area, we determined coffee cover and forest structure in 40 forest margins that differed in time since deforestation. Both the absolute and relative deforestation rates were lower at coffee‐growing elevations compared with at higher elevations (?10/20% vs. ?40/50% comparing relative rates at 1800 m asl and 2300–2500 m asl, respectively). Within the coffee‐growing elevation, the proportion of sites with high coffee cover (>20%) was significantly higher in stable margins (42% of sites that had been in the same location for the entire period) than in recently changed margins (0% of sites where expansion of annual crops had changed the margin). Disturbance level and forest structure did not differ between sites with 30% or 3% coffee. However, a growing body of literature on gradients of coffee management in Ethiopia reports coffee's negative effects on abundances of forest‐specialist species. Even if the presence of coffee slows down the conversion of forest to annual‐crop agriculture, there is a risk that an intensification of coffee management will still threaten forest biodiversity, including the genetic diversity of wild coffee. Conservation policy for Ethiopian forests thus needs to develop strategies that acknowledge that forests without coffee production may have higher deforestation risks than forests with coffee production and that forests with coffee production often have lower biodiversity value. Efectos de la Administración Cafetalera sobre las Tasas de Deforestación y la Integridad de los Bosques