Malhi Y.,University of Oxford |
Adu-Bredu S.,Forestry Research Institute of Ghana |
Asare R.A.,Nature Conservation Research Center |
Lewis S.L.,University College London |
And 2 more authors.
Philosophical Transactions of the Royal Society B: Biological Sciences | Year: 2013
The rainforests are the great green heart of Africa, and present a unique combination of ecological, climatic and human interactions. In this synthesis paper, we review the past and present state processes of change in African rainforests, and explore the challenges and opportunities for maintaining a viable future for these biomes. We drawin particular on the insights and new analyses emerging from the Theme Issue on 'African rainforests: past, present and future' of Philosophical Transactions of the Royal Society B. A combination of features characterize the African rainforest biome, including a history of climate variation; forest expansion and retreat; a long history of human interaction with the biome; a relatively low plant species diversity but large tree biomass; a historically exceptionally high animal biomass that is now being severely hunted down; the dominance of selective logging; small-scale farming and bushmeat hunting as the major forms of direct human pressure; and, in Central Africa, the particular context of mineral- and oil-driven economies that have resulted in unusually low rates of deforestation and agricultural activity. We conclude by discussing how this combination of factors influences the prospects for African forests in the twenty-first century. © 2013 The Authors.
Marfo E.,Forestry Research Institute of Ghana |
Mckeown J.P.,Tropenbos International Ghana Programme
Forest Policy and Economics | Year: 2013
Negotiating a policy change involves formation of coalitions of actors in a particular policy subsystem with substantial mobilisation of resources to deploy strategic actions to direct the outcome of the process to a certain interest. The Advocacy Coalition Framework (ACF) has been demonstrated as a useful heuristic framework to explain policy change within a particular political system. This study applies the ACF to the negotiation of a policy change for the supply of timber to the domestic market in Ghana. The study largely confirms selected coalition hypotheses and makes a contribution to a possible revision of some of them. © 2013 Elsevier B.V.
Fauset S.,University of Leeds |
Baker T.R.,University of Leeds |
Lewis S.L.,University of Leeds |
Lewis S.L.,University College London |
And 5 more authors.
Ecology Letters | Year: 2012
The future of tropical forests under global environmental change is uncertain, with biodiversity and carbon stocks at risk if precipitation regimes alter. Here, we assess changes in plant functional composition and biomass in 19 plots from a variety of forest types during two decades of long-term drought in Ghana. We find a consistent increase in dry forest, deciduous, canopy species with intermediate light demand and a concomitant decrease in wet forest, evergreen, sub-canopy and shade-tolerant species. These changes in composition are accompanied by an increase in above-ground biomass. Our results indicate that by altering composition in favour of drought-tolerant species, the biomass stocks of these forests may be more resilient to longer term drought than short-term studies of severe individual droughts suggest. © 2012 Blackwell Publishing Ltd/CNRS.
Adum G.B.,Range Resources |
Eichhorn M.P.,University of Nottingham |
Oduro W.,Range Resources |
Ofori-Boateng C.,Range Resources |
And 2 more authors.
Conservation Biology | Year: 2013
There is a lack of quantitative information on the effectiveness of selective-logging practices in ameliorating effects of logging on faunal communities. We conducted a large-scale replicated field study in 3 selectively logged moist semideciduous forests in West Africa at varying times after timber extraction to assess post logging effects on amphibian assemblages. Specifically, we assessed whether the diversity, abundance, and assemblage composition of amphibians changed over time for forest-dependent species and those tolerant of forest disturbance. In 2009, we sampled amphibians in 3 forests (total of 48 study plots, each 2 ha) in southwestern Ghana. In each forest, we established plots in undisturbed forest, recently logged forest, and forest logged 10 and 20 years previously. Logging intensity was constant across sites with 3 trees/ha removed. Recently logged forests supported substantially more species than unlogged forests. This was due to an influx of disturbance-tolerant species after logging. Simultaneously Simpson's index decreased, with increased in dominance of a few species. As time since logging increased richness of disturbance-tolerant species decreased until 10 years after logging when their composition was indistinguishable from unlogged forests. Simpson's index increased with time since logging and was indistinguishable from unlogged forest 20 years after logging. Forest specialists decreased after logging and recovered slowly. However, after 20 years amphibian assemblages had returned to a state indistinguishable from that of undisturbed forest in both abundance and composition. These results demonstrate that even with low-intensity logging (≤3 trees/ha) a minimum 20-year rotation of logging is required for effective conservation of amphibian assemblages in moist semideciduous forests. Furthermore, remnant patches of intact forests retained in the landscape and the presence of permanent brooks may aid in the effective recovery of amphibian assemblages. © 2012 Society for Conservation Biology.
Isaac M.E.,University of Toronto |
Anglaaere L.C.N.,Forestry Research Institute of Ghana |
Borden K.,University of Toronto |
Adu-Bredu S.,Forestry Research Institute of Ghana
Agriculture, Ecosystems and Environment | Year: 2014
Land-use practises converting forests to tree-crop systems commonly result in large expanses of intensively managed landscapes. However, some farming practices retain trees and other forest structural components during conversion as a means to confer favorable conditions through agroecological intensification. Understanding root plasticity in situ in response to such a multi-species rooting environment is important to avoid interspecific resource competition. This, however, is an often-understudied parameter due to methodological constraints. Here, we investigate two dominant parameters of root ecology, coarse root distribution and soil water acquisition, of the economically important tree-crop, Theobroma cacao, in monoculture and in mixture with shade trees (agroforestry systems) at two edaphically contrasting sites [sandstone (sandy loam) and phyllite-granite (loam) derived soils] in Ghana, West Africa. In monoculture and in mixture, we employed ground-penetrating radar to detect cocoa coarse root distribution and plant-soil δ18O isotopic signatures to estimate soil water acquisition zones. In monoculture, detected cocoa coarse root vertical distribution differed between sandy loams and loams, with a less dispersed distribution and a higher mean coarse root depth in sandy loams. Detected vertical coarse root distribution was also strongly differentiated between cocoa in monoculture and in mixture; cocoa exhibited restricted root allocation to a smaller zone in the presence of a shade tree, in sandy loam soils. In monoculture, cocoa plant δ18O isotopic signature matched a narrow soil δ18O isotopic zone, while this matched plant-soil zone expanded for cocoa in mixture, illustrating larger soil water acquisition zones in the presence of a shade tree but exclusively in sandy loam soils. We show that under certain conditions, root modification in the presence of a secondary species may limit competition as tree-crop root plasticity differentiates belowground allocation and resource acquisition zones in an agroforestry system. © 2013 Elsevier B.V.
Isaac M.E.,University of Toronto |
Anglaaere L.C.N.,Forestry Research Institute of Ghana
Ecology and Evolution | Year: 2013
Tree root distribution and activity are determinants of belowground competition. However, studying root response to environmental and management conditions remains logistically challenging. Methodologically, nondestructive in situ tree root ecology analysis has lagged. In this study, we tested a nondestructive approach to determine tree coarse root architecture and function of a perennial tree crop, Theobroma cacao L., at two edaphically contrasting sites (sandstone and phyllite-granite derived soils) in Ghana, West Africa. We detected coarse root vertical distribution using ground-penetrating radar and root activity via soil water acquisition using isotopic matching of δ18O plant and soil signatures. Coarse roots were detected to a depth of 50 cm, however, intraspecifc coarse root vertical distribution was modified by edaphic conditions. Soil δ18O isotopic signature declined with depth, providing conditions for plant-soil δ18O isotopic matching. This pattern held only under sandstone conditions where water acquisition zones were identifiably narrow in the 10-20 cm depth but broader under phyllite-granite conditions, presumably due to resource patchiness. Detected coarse root count by depth and measured fine root density were strongly correlated as were detected coarse root count and identified water acquisition zones, thus validating root detection capability of ground-penetrating radar, but exclusively on sandstone soils. This approach was able to characterize trends between intraspecific root architecture and edaphic-dependent resource availability, however, limited by site conditions. This study successfully demonstrates a new approach for in situ root studies that moves beyond invasive point sampling to nondestructive detection of root architecture and function. We discuss the transfer of such an approach to answer root ecology questions in various tree-based landscapes. © 2013 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.
Dumenu W.K.,Forestry Research Institute of Ghana
Ecosystem Services | Year: 2013
The ecosystem services of urban forests are under threat in Ghana due to continuous conversion of urban green spaces into other land uses. The loss of urban forests is contributing to decreases in resilience and increases in vulnerability of urban dwellings to flooding and windstorms. Investing in management of urban forests and including them in urban development planning is critical and can only be pursued if economic value of urban forest services are properly assessed and appreciated. In this paper the Contingent Valuation Method is used to estimate the economic value of non-market benefits of an urban forest in Ghana. Using Cost-Benefit Analysis, the monetary value of the urban forest in the course of time was estimated. The stated monetary value of the urban forest was found to be US$694,765.50. The Net Present Value of the urban green space was US$2,786,620.65. The estimated economic value covered nine times the 10-year maintenance cost of the urban green space. As a seminal work on economic valuation of a standing urban forest in Ghana, it is envisaged that the results will inspire further research in this field, and demonstrate the need for investment in creation and management of urban forests. © 2013 Elsevier B.V.
Kankam B.O.,Forestry Research Institute of Ghana |
Oduro W.,Kwame Nkrumah University Of Science And Technology
African Journal of Ecology | Year: 2012
The quality of seed treatment by frugivores has an effect on seed removal after dispersal, seed germination and tree recruitment. We provide information on postdispersal seed removal, germination and subsequent recruitment in tropical forest tree species Antiaris toxicaria in Ghana. We tested whether postdispersal seed removal and germination rates were differentially affected by the following seed treatments: seeds that were spat out by monkeys with all fruit pulp removed and spitting seeds with fruit pulp partially removed as observed in some birds and bats. We used seeds of intact ripened fruits as control. Frugivore seed treatment and distance from bole affected seed removal patterns, whereas intact seeds were significantly removed from all seed stations. The germination success was greater for seeds that were spat out by monkeys and poor for seeds with fruit pulp partially removed and intact fruits. More recruits were recorded at the edge of the adult A. toxicaria canopy radius. There was weak relationship (r 2=0.042) between the number of recruits and distance away from the adult tree. Results suggest that the subsequent recruitment in tropical forest tree species may be enhanced by some frugivore fruit-handling behaviour where fruit pulp is removed from the seeds without destroying the seeds. © 2011 Blackwell Publishing Ltd.
Schoneveld G.C.,Center for International Forestry Research |
Schoneveld G.C.,University Utrecht |
German L.A.,Center for International Forestry Research |
Nutako E.,Forestry Research Institute of Ghana
Ecology and Society | Year: 2011
The rapidly growing biofuel sector in Africa has, in recent years, been received with divided interest. As part of a contemporary wave of agricultural modernization efforts, it could make invaluable contributions to rural poverty. Conversely, it could also engender socioeconomically and environmentally detrimental land use changes as valuable land resources are converted to plantation agriculture. This research analyzes the impacts and impact pathways of biofuel feedstock development in Ghana. It finds that companies are accessing large contiguous areas of customary land through opaque negotiations with traditional authorities, often outside the purview of government and customary land users. Despite lack of participation, most customary land users were highly supportive of plantation development, with high expectations of 'development' and 'modernization.' With little opposition and resistance, large areas of agricultural and forested land are at threat of being converted to plantation monoculture. A case study analysis shows that this can significantly exacerbate rural poverty as communities lose access to vital livelihood resources. Vulnerable groups, such as women and migrants, are found to be most profoundly affected because of their relative inability in recovering lost livelihood resources. Findings suggest that greater circumspection by government is warranted on these types of large-scale land deals. © 2011 by the author(s).
Kankam B.O.,Forestry Research Institute of Ghana |
Sicotte P.,University of Calgary
Folia Primatologica | Year: 2013
We explore the factors influencing the abundance of Colobus vellerosus in 11 forest fragments [Boabeng-Fiema Monkey Sanctuary and 9 surrounding forest fragments (range: 3.2-190 ha)] in the forest-savanna transition zone of Ghana. We used a 'complete' count for the colobus census in the fragments. We determined the fragment sizes using geographic information system methods and assessed forest fragment quality (tree species richness). Colobus individuals were absent from 4 forest fragments but present in 7 (densities of 0.13/ha-1.63/ha). We modelled colobus density using Poisson regression and selected models based on corrected Akaike information criterion model weights. Fragment size and tree species richness in the fragments were positively associated with colobus density, whereas isolation distance of the forest fragments (range: 20-5,632 m) was negatively associated with colobus density. Our analysis suggests that the isolation distance between the fragments and Boabeng does impede colobus movement. As the colobus populations in Boabeng and Fiema increase, some of the unoccupied fragments may become more attractive to dispersing monkeys. Management measures that aim at increasing tree species richness within fragments, while maintaining some large trees between fragments, might help to increase the occupancy of some of the fragments that currently have no permanent colobus groups. Copyright © 2013 S. Karger AG, Basel.