Tropical Forest Dynamics

In literature on Natural Resource Management related policies in Africa and Cameroon in particular, Colonial heritage was defined and identified. The question of this paper is whether "community forestry" which promotes giving back the forest to people breaks with this tradition. The key elements of Colonial heritage in resource management were deduced from literature. Based on these benchmarks the program and practice of community forestry in Cameroon were evaluated. Data about community forestry in Cameroon was collected in 10 selected communities in 2009/10. Today in practice community forestry favors techno-scientific knowledge about the forest, separate nature from human life, is a bureaucratic controlled engagement with nature and is aimed to make nature and people productive. The benchmark identifies a strong Colonial heritage within community forestry in Cameroon and questions whether the aim of including the local people in forest management, correcting their previous exclusion by the Colonial policy in the management of their forest resources, thus, the self determined life of people within the forest can be reached.

Estimates of carbon-stock changes in forest ecosystems require information on dead wood decomposition rates. In the Amazon, the lack of data is dramatic due to the small number of studies and the large range of forest types. The aim of this study was to estimate the decomposition rate of coarse woody debris (CWD) in two oligotrophic undisturbed forest formations of the northern Brazilian Amazon: seasonally flooded and unflooded. We analyzed 20 arboreal individuals (11 tree species and 3 palm species) with distinct wood-density categories. The mean annual decomposition rate of all samples independent of forest formation ranged from 0.044 to 0.963 yr À1 , considering two observation periods (12 and 24 months). The highest rate (0.732 ± 0.206 [SD] yr À1) was observed for the lowest wood-density class of palms, whereas the lowest rate (0.119 ± 0.101 yr À1) was determined for trees with high wood density. In terms of forest formation, the rates values differ when weighted by the wood-density classes, indicating that unflooded forest (0.181 ± 0.083 [SE] yr À1 ; mean decay time 11–30 years) has a decomposition rate $19% higher than the seasonally flooded formations (0.152 ± 0.072 yr À1 ; 13–37 years). This result reflects the dominance of species with high wood density in seasonally flooded formations. In both formations 95% of the dead wood is expected to disappear within 30–40 years. Based on our results, we conclude that the CWD decomposition in the studied area is slower in forests on nutrient-poor seasonally flooded soils, where structure and species composition result in $40% of the aboveground biomass being in tree species with high wood density. Thus, it is estimated that CWD in seasonally flooded forest formations has longer residence time and slower carbon release by decomposition (respiration) than in unflooded forests. These results improve our ability to model stocks and fluxes of carbon derived from decomposition of dead wood in undisturbed oligotrophic forests in the Rio Negro-Rio Branco Basin, northern Brazilian Amazon.

Despite their importance as sources of ecosystem services supporting the livelihoods of millions of people, forest ecosystems have been changing into other land use systems over the past decades across the world. While forest cover change dynamics have been widely documented in various ecological systems, how these changes affect ecosystem service values has received limited attention. In this study we assessed the impact of land-use/land-cover dynamics on ecosystem service values in dry Afromontane forest in Northern Ethiopia. We estimated ecosystem service values and their changes based on the benefit transfer method using land cover data of the years 1985, 2000, and 2016 with their corresponding locally valid value coefficients and from the Ecosystem service valuation database. The total ecosystem service values of the whole study area were about USD 16.6, 19.0, and 18.1 million in 1985, 2000, and 2016, respectively. The analyses indicated an increase in ecosystem service values from 1985 to 2000 and a decrease in ecosystem service values from 2000 to 2016. Similarly, the contribution of specific ecosystem services increased in the first study period and decreased in the second study period. The findings highlight how forest cover dynamics can be translated into changes in ecosystem service values in dry Afromontane forest ecosystems in Northern Ethiopia and showed how specific ecosystem services contributed to the observed trends. The findings also illustrated the temporal heterogeneity in the impacts of land-use/land-cover dynamics on values of ecosystem services. The findings can serve as crucial inputs for policy and strategy formulations for the sustainable use and management of forest resources and can also guide the allocation of limited resources among competing demands to safeguard the ecosystems that offer the best-valued services.

Question: Have liana density and biomass increased in central Amazonia over the last 10 years? Can a spatially explicit consideration of liana mortality and recruitment rates across hydro-edaphic and tree turnover gradients at the landscape scale explain changes in liana density and biomass? Location: Ducke Forest Reserve, 26 km north of Manaus, Amazonas, Brazil. Methods: Data were collected on 30–1 ha permanent plots in a central Amazonia undisturbed old-growth rain forest 10 years after the first census. We measured lia-nas at 1.3 cm above their rooting point, with a diameter (D) ≥ 5 cm and subsampled lianas ≥1 cm diameter in 0.25 ha per plot. We estimated above-ground density and biomass changes, mortality rate, recruitment and diameter increase. Soil cations and available P were reduced to two dimensions with PCA and the first axis used as the descriptor of soil fertility. Height above the nearest drainage, a proxy for water availability , tree turnover (D ≥ 10 cm) and soil fertility were used as predictors of liana dynamics. Results: No significant change in liana density and biomass, averaged over the 30-km 2 landscape, was observed over the last 10 years. In 2014, liana density was generally higher in more fertile soils, and it increased in areas closer to the water table and with higher tree turnover in the valleys. This pattern resulted from the higher liana recruitment rates in valley plots closer to the water table. Liana mortality rates were uniform across plots, similar among the diameter classes and, on average, higher than recruitment. Conclusion: We did not find any evidence that liana density and biomass have been increasing in this Neotropical site over the last 10 years. These findings suggest that the current knowledge on liana increase trends in the Neotropics should be reviewed if supported by further tropical studies. K E Y W O R D S above-ground biomass, central Amazonia, climbing ecology, liana mortality, liana recruitment, liana turnover, old-growth rain forest, tree turnover, vines

Palm hearts are a traditional amerindian food currently used as a delicacy in international cuisine. They correspond to the developing leaves of some neotropical palm species, and their extraction implies cutting the palm tree. As most palm hearts come from wild stands, sustainability studies are necessary to avoid overexploitation. Prestoea acuminata is a clonal palm used as a source of palm hearts in southern Colombia and northern Ecuador. We conducted a demographic study, and elaborated a matrix model, to assess the ecological sustainability of this extractive activity and to provide management recommendations. Prestoea acuminata exhibits a low resource density (127 palm hearts ha-1 in our survey) and has a very slow growth rate, taking 23-40 years to reach an appropriate size for palm heart extraction. This and the fact that the few harvestable stems are also responsible for sexual reproduction make P. acuminata suitable only for household extraction. We recommend a maximum annual extraction of 10% and the discussion and implementation of a management plan that should include all stakeholders

Understanding the processes that determine above‐ground biomass (AGB) in Amazonian forests is important for predicting the sensitivity of these ecosystems to environmental change and for designing and evaluating dynamic global vegetation models (DGVMs). AGB is determined by inputs from woody productivity [woody net primary productivity (NPP)] and the rate at which carbon is lost through tree mortality. Here, we test whether two direct metrics of tree mortality (the absolute rate of woody biomass loss and the rate of stem mortality) and/or woody NPP, control variation in AGB among 167 plots in intact forest across Amazonia. We then compare these relationships and the observed variation in AGB and woody NPP with the predictions of four DGVMs. The observations show that stem mortality rates, rather than absolute rates of woody biomass loss, are the most important predictor of AGB, which is consistent with the importance of stand size structure for determining spatial variation in AGB. ...