A thesis submitted to the Department of Silviculture and Forest Management, Kwame Nkrumah University of Science and Technology in partial fulfilment of the requirements for the award of Master of Science, 2002
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A thesis submitted to the Department of Silviculture and Forest Management of the Faculty of Renewable Natural Resources, Kwame Nkrumah University of Science and Technology, in partial fulfillment of the requirements for the degree of... more
A thesis submitted to the Department of Silviculture and Forest Management of the Faculty of Renewable Natural Resources, Kwame Nkrumah University of Science and Technology, in partial fulfillment of the requirements for the degree of Doctor of Philosophy (PhD) in Silviculture and Forest Management, 2014
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We report above-ground biomass (AGB), basal area, stem density and wood mass density estimates from 260 sample plots (mean size: 1.2 ha) in intact closed-canopy tropical forests across 12 African countries. Mean AGB is 395.7 Mg dry mass... more
We report above-ground biomass (AGB), basal area, stem density and wood mass density estimates from 260 sample plots (mean size: 1.2 ha) in intact closed-canopy tropical forests across 12 African countries. Mean AGB is 395.7 Mg dry mass ha-1 (95% CI: 14.3), substantially higher than Amazonian values, with the Congo Basin and contiguous forest region attaining AGB values (429 Mg ha-1) similar to those of Bornean forests, and significantly greater than East or West African forests. AGB therefore appears generally higher in palaeo- compared with neo-tropical forests. However, mean stem density is low (426±11 stems ha-1 greater than or equal to 100 mm diameter) compared with both Amazonian and Bornean forests (cf. approx. 600) and is the signature structural feature of African tropical forests. While spatial autocorrelation complicates analyses, AGB shows a positive relationship with rainfall in the driest nine months of the year, and an opposite association with the wettest three month...
Fine roots constitute a significant component of the net primary productivity (NPP) of forest ecosystems but are much less studied than aboveground NPP. Comparisons across sites and regions are also hampered by inconsistent methodologies,... more
Fine roots constitute a significant component of the net primary productivity (NPP) of forest ecosystems but are much less studied than aboveground NPP. Comparisons across sites and regions are also hampered by inconsistent methodologies, especially in tropical areas. Here, we present a novel dataset of fine root biomass, productivity, residence time, and allocation in tropical old‐growth rainforest sites worldwide, measured using consistent methods, and examine how these variables are related to consistently determined soil and climatic characteristics. Our pantropical dataset spans intensive monitoring plots in lowland (wet, semi‐deciduous, and deciduous) and montane tropical forests in South America, Africa, and Southeast Asia (n = 47). Large spatial variation in fine root dynamics was observed across montane and lowland forest types. In lowland forests, we found a strong positive linear relationship between fine root productivity and sand content, this relationship was even stro...
Research Interests: Environmental Science, Africa, Biomass, Productivity, Ecology, and 15 moreGlobal Change Biology, Medicine, Biological Sciences, Biodiversity Conservation, Environmental Sciences, Forests, Rainforest, Plant Roots, Amazon forest, Deciduous, Ecosystem, Litter Production, Allocation, Aluminum Toxicity, and NET PRIMARY PRODUCTIVITY
AimTree crowns determine light interception, carbon and water exchange. Thus, understanding the factors causing tree crown allometry to vary at the tree and stand level matters greatly for the development of future vegetation modelling... more
AimTree crowns determine light interception, carbon and water exchange. Thus, understanding the factors causing tree crown allometry to vary at the tree and stand level matters greatly for the development of future vegetation modelling and for the calibration of remote sensing products. Nevertheless, we know little about large‐scale variation and determinants in tropical tree crown allometry. In this study, we explored the continental variation in scaling exponents of site‐specific crown allometry and assessed their relationships with environmental and stand‐level variables in the tropics.LocationGlobal tropics.Time periodEarly 21st century.Major taxa studiedWoody plants.MethodsUsing a dataset of 87,737 trees distributed among 245 forest and savanna sites across the tropics, we fitted site‐specific allometric relationships between crown dimensions (crown depth, diameter and volume) and stem diameter using power‐law models. Stand‐level and environmental drivers of crown allometric re...
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Differential tree seedling recruitment across forest-savanna ecotones is poorly understood, but hypothesized to be influenced by vegetation cover and associated factors. In a 3-y-long field transplant experiment in the forest-savanna... more
Differential tree seedling recruitment across forest-savanna ecotones is poorly understood, but hypothesized to be influenced by vegetation cover and associated factors. In a 3-y-long field transplant experiment in the forest-savanna ecotone of Ghana, we assessed performance and root allocation of 864 seedlings for two forest (Khaya ivorensis and Terminalia superba) and two savanna (Khaya senegalensis and Terminalia macroptera) species in savanna woodland, closed-woodland and forest. Herbaceous vegetation biomass was significantly higher in savanna woodland (1.0 ± 0.4 kg m−2 vs 0.2 ± 0.1 kg m−2 in forest) and hence expected fire intensities, while some soil properties were improved in forest. Regardless, seedling survival declined significantly in the first-year dry-season for all species with huge declines for the forest species (50% vs 6% for Khaya and 16% vs 2% for Terminalia) by year 2. After 3 y, only savanna species survived in savanna woodland. However, best performance for s...
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Through interpretations of remote sensing data and/or theoretical propositions, the idea that forest and savanna represent "alternative stable states" is gaining increasing acceptance. Filling an observational gap, we present... more
Through interpretations of remote sensing data and/or theoretical propositions, the idea that forest and savanna represent "alternative stable states" is gaining increasing acceptance. Filling an observational gap, we present detailed stratified floristic and structural analyses for forest and savanna stands mostly located within zones of transition (where both vegetation types occur in close proximity) in Africa, South America and Australia. Woody plant leaf area index variation was related in a similar way to tree canopy cover for both savanna and forest with substantial overlap between the two vegetation types. As total woody plant canopy cover increased, so did the contribution of middle and lower strata of woody vegetation to this total. Herbaceous layer cover also declined as woody cover increased. This pattern of understorey grasses and herbs being progressively replaced by shrubs as canopy closure occurs was found for both savanna and forests and on all continents....
Research Interests: Earth Sciences, Geology, Ecology, Southern Africa, Alternative Stable States, and 15 moreCanopy, Biological Sciences, Environmental Sciences, Tropical forest, Physical sciences, Biogeosciences, National Park, Brazilian cerrado, Amazonian forest, Science Technology, Functional Types, Tree Height, Tree Canopy, Basal Area, and Shrub
Variations in leaf mass per unit area (Ma) and foliar concentrations of N, P, C, K, Mg and Ca were determined for 365 trees growing in 23 plots along a West African precipitation gradient ranging from 0.29 to 1.62 m a–1. Contrary to... more
Variations in leaf mass per unit area (Ma) and foliar concentrations of N, P, C, K, Mg and Ca were determined for 365 trees growing in 23 plots along a West African precipitation gradient ranging from 0.29 to 1.62 m a–1. Contrary to previous studies, no marked increase in Ma with declining precipitation was observed, but savanna tree foliar [N] tended to be higher at the drier sites (mass basis). Generally, Ma was slightly higher and [N] slightly lower for forest vs savanna trees with most of this difference attributable to differences in soil chemistry. No systematic variations in [P], [Mg] and [Ca] with precipitation or between trees of forest vs savanna stands were observed. We did, however, find a marked increase in foliar [K] of savanna trees as precipitation declined, with savanna trees also having a significantly lower [K] than those of nearby forest. These differences were not related to differences in soil nutrient status and were accompanied by systematic changes in [C] of...
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Background: There is no generally agreed classification scheme for the many different vegetation formation types occurring in the tropics. This hinders cross-continental comparisons and causes confusion as words, such as... more
Background: There is no generally agreed classification scheme for the many different vegetation formation types occurring in the tropics. This hinders cross-continental comparisons and causes confusion as words, such as 'forest'and 'savanna'have different meanings to different people. Tropical vegetation formations are therefore usually imprecisely and/or ambiguously defined in modelling, remote sensing and ecological studies. Aims: To integrate observed variations in tropical vegetation structure and floristic ...
Research Interests: Geography, Plant Biology, Ecology, Floristics, Tropics, and 3 moreTropical forest, Understory, and Shrub
We report above-ground biomass (AGB), basal area, stem density and wood mass density estimates from 260 sample plots (mean size: 1.2 ha) in intact closed-canopy tropical forests across 12 African countries. Mean AGB is 395.7 Mg dry mass... more
We report above-ground biomass (AGB), basal area, stem density and wood mass density estimates from 260 sample plots (mean size: 1.2 ha) in intact closed-canopy tropical forests across 12 African countries. Mean AGB is 395.7 Mg dry mass ha −1 (95% CI: 14.3), substantially higher than Amazonian values, with the Congo Basin and contiguous forest region attaining AGB values (429 Mg ha −1 ) similar to those of Bornean forests, and significantly greater than East or West African forests. AGB therefore appears generally higher in palaeo- compared with neotropical forests. However, mean stem density is low (426 ± 11 stems ha −1 greater than or equal to 100 mm diameter) compared with both Amazonian and Bornean forests (cf. approx. 600) and is the signature structural feature of African tropical forests. While spatial autocorrelation complicates analyses, AGB shows a positive relationship with rainfall in the driest nine months of the year, and an opposite association with the wettest three ...
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Research Interests: Earth Sciences, Biogeochemistry, Biomass, Biological Sciences, Environmental Sciences, and 15 moreAllometry, Boreal forest Archaeology, Biogeosciences, Coefficient of Variation, Forest Structure, Forest ecosystem, Forest and Tree Biomass Modelling, Carbon Stock and Allometric Equations, Amazon basin, European Geosciences Union, Above ground biomass, Arctic Tundra, Basal Area, Allometric equation, and Dry Season
Promoting the consumption of forest plant foods is a sustainable way of ensuring good nutrition and food security. This study assessed traditional knowledge on and use of forest plant foods in three administrative districts of Ghana and... more
Promoting the consumption of forest plant foods is a sustainable way of ensuring good nutrition and food security. This study assessed traditional knowledge on and use of forest plant foods in three administrative districts of Ghana and evaluated their potentials for domestication and processing. A total of 606 households were randomly selected and interviewed using enumerator-administered questionnaires. Validation workshops with 30 participants were held in each district to help identify the species mentioned. In all, 83 species belonging to 45 families were documented. Knowledge of forest plant foods was found to be higher among older respondents than younger ones, indicating an urgent need to document traditional knowledge on forest plant foods before it disappears along with the older generation. Artocarpus altilis (Parkinson) Fosberg and Tetrapleura tetraptera (Schumach. & Thonn.) Taub. were identified as potential species for domestication and processing. Domestication and pr...
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This paper discusses the digitization of indigenous knowledge on forest foods and medicine for the effective management of Ghana’s forest resources. The paper is based on a survey conducted in nine communities in Ghana where primary data... more
This paper discusses the digitization of indigenous knowledge on forest foods and medicine for the effective management of Ghana’s forest resources. The paper is based on a survey conducted in nine communities in Ghana where primary data were obtained from 606 respondents using in-depth face-to-face interviews. The aim of the study was to assess what knowledge local communities had about products of the forest especially indigenous forest foods and medicine. The findings reveal that local communities have an in-depth knowledge of indigenous forest foods and medicines. They are conversant with what foods and medicines are available in the forests, how they are consumed and when they mature. The study reveals that consumption of indigenous forest foods is on the decline, while the use of traditional medicine is on the ascendancy. The study recommends the promulgation of laws and legal instruments to protect communities from bio-piracy.