Papers by Emmanuel Chidumayo
Seed science research, Apr 24, 2024
Differences in germination traits of timeseparated seed collections of dry forest species from Ce... more Differences in germination traits of timeseparated seed collections of dry forest species from Central Zambia and the potential role of climate. Seed Science Research 1-10.
Forest Ecology and Management, Mar 1, 2019
Brachystegia-Julbernardia (miombo) woodlands of east and southern Africa are divided into dry (< ... more Brachystegia-Julbernardia (miombo) woodlands of east and southern Africa are divided into dry (< 1000 mm annual rainfall) and wet (> 1000 mm). These woodlands first became established about 14,500 years ago. Since the migration of the Bantu people 5000 years ago, miombo woodlands have experienced widespread degradation and deforestation. There is little long-term data on tree growth and forest productivity for miombo woodlands and yet such data are required for the proper management of these woodlands. This study used tree growth data from 35 temporary plots in regrowth of 5-49 years old, and six permanent sample plots (PSPs) in old growth forest, which were monitored over a 28-year period (1990-2018). These data were used to investigate tree diameter growth and develop models of forest dynamics in wet and dry miombo woodlands. The study found that variations in tree diameter and stand basal area increments are strongly driven by stand age, tree size and density and that growth rates are higher in wet than dry miombo. Overall miombo woodland trees grew slowly at a rate of 0.34-0.50 cm yr −1 in re-growth areas. Most of the species in uneven-aged old-growth stands in dry miombo grew by 0.15 cm yr −1 with no significant annual differences although variations among conspecifics were large. Models predicted tree diameter increments of 0.10-0.24 cm yr −1 for stands of 100 years old. Transitions from one 5-cm diameter class to the next was estimated to take over 20 years and significant shifts in stand tree diameter distribution curves require over 25 years because of the low annual diameter increments. Stand responses to degradation varied from site to site and were driven by the number of saplings transiting into small diameter size classes. On the temporary regrowth plots basal areas averaged 7.1 m 2 ha −1 and 9.9 m 2 ha −1 in dry and wet re-growth miombo, respectively, with positive increments estimated at 0.40 m 2 ha −1 yr −1 in dry miombo and 0.53 m 2 ha −1 yr −1 in wet miombo. By contrast, average basal area increment on old-growth PSPs was negative, at −0.26 m 2 ha −1 yr −1 over the 1990-2018 period, due to cutting and fire damage. Such drivers of forest degradation need to be controlled, especially in old-growth miombo, to maintain forest health and prevent decline in biomass.
South African Journal of Zoology, 1980
An old quarry, 2,5 ha in size near Livingstone in southern Zambia was kill- and live-trapped betw... more An old quarry, 2,5 ha in size near Livingstone in southern Zambia was kill- and live-trapped between September 1974 and December 1976 to determine ecological relations among rodent species inhabiting it. Seven species were found to comprise the old quarry rodent community. Praomys natalensis was by far the most common although Saccostomus campestris and Lemniscomys griselda were also abundant. Four species (Tatera leucogaster, Steatomys pratensis, Mus minutoides and Aethomys chrysophilus were rare. Food and micro-habitat preferences of S. campestris and P. natalensis appeared similar. Seasonal fluctuations characterized the P. natalensis population while L Griselda was absent from the site during the latter part of the rainy season and early in the dry season. Pre-weaning survival of P. natalensis was very low, particularly early in the breeding season. The survival of the trappable population was good but declined following a burn at the study site. P. natalensis recruited into the population from May-July, lost between 20 and 35% of their body mass during the August-October period. Body mass increased as rodents attained sexual maturity early in the rainy season.
CRC Press eBooks, May 19, 2021
Desertification control bulletin, 1999
South African Journal of Botany, 2019
Geoxyles are plants with massive underground and diminutive aboveground parts and in sub-Saharan ... more Geoxyles are plants with massive underground and diminutive aboveground parts and in sub-Saharan Africa this life form is most diverse in south-central Africa. However, little is known about the population ecology of these plants, especially in south-central Africa. The purpose of this research was to investigate the demography and biomass structure of Lannea edulis, a widespread geoxyle in south-central Africa, using census, phenology and biomass data obtained over a 20-year period at a site in central Zambia, southern Africa. Mast fruiting in L. edulis is rare and seed germination rate and seedling mortality vary from year to year, resulting in episodic recruitment of juveniles into the population. Juvenile plants have a tuberous fleshy root that is transformed into a thickbarked woody taproot in adults. Frequent dieback of aerial shoots due to fire and herbivory induces the formation and growth of subsurface stems. The average oven-dry biomass of a L. edulis plant was 370 g of which shoots and roots represented 10% and 90%, respectively, thereby confirming that this geoxyle has indeed massive belowground parts. The demography of L. edulis is greatly influenced by variable annual recruitment of juveniles into the population and large individuals were estimated to live for more than 60 years.
Science
Take-down policy If you believe that this document breaches copyright please contact us providing... more Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.
Proceedings of the National Academy of Sciences, 2020
Significance We develop a biogeographic approach to analyzing the presence of alternative stable ... more Significance We develop a biogeographic approach to analyzing the presence of alternative stable states in tropical biomes. Whilst forest–savanna bistability has been widely hypothesized and modeled, empirical evidence has remained scarce and controversial, and here, applying our method to Africa, we provide large-scale evidence that there are alternative states in tree species composition of tropical vegetation. Furthermore, our results have produced more accurate maps of the forest and savanna distributions in Africa, which take into account differences in tree species composition, and a complex suite of determinants. This result is not only important for understanding the biogeography of the continent but also, to guide large-scaled tree planting and restoration efforts planned for the region.
Journal of Biogeography, 2018
Aim: In tropical Africa, savannas cover huge areas, have high plant species richness and are cons... more Aim: In tropical Africa, savannas cover huge areas, have high plant species richness and are considered as a major natural resource for most countries. There is, however, little information available on their floristics and biogeography at the continental scale, despite the importance of such information for our understanding of the drivers of species diversity at various scales and for effective conservation and management. Here, we collated and analysed floristic data from across the continent in order to propose a biogeographical regionalization for African savannas. Location: We collated floristic information (specifically woody species lists) for 298 samples of savanna vegetation across Africa, extending from 18°N to 33°S and from 17°W to 48°E. Taxa: We focused on native woody species. Methods: We used ordination and clustering to identify the floristic discontinuities and gradual transitions across African savannas. Floristic relationships, specificity and turnover, within and between floristic clusters, were analysed using a (dis-)similarity-based approach. Results: We identified eight floristic clusters across African savannas which in turn were grouped into two larger macro-units. Ordinations at species and genus levels showed a clear differentiation in woody species composition between the North/ West macro-unit and the South/East macro-unit. This floristic discontinuity matches to the High (i.e. N&W) and Low (S&E) division of Africa previously proposed by White (1983) and which tracks climatic and topographical variation. In the N&W savannas, the floristic gradient determined by rainfall was partitioned into the Sudanian (drier) and Guinean (wetter) clusters. Within the highly heterogeneous S&E savannas and woodlands, six clusters were identified: Ugandan, Ethiopian, Mozambican, Zambezian, Namibian and South African. Main conclusions: The proposed pan-African classification of savannas and woodlands might assist the development of coordinated management and conservation policies.
Routledge eBooks, Sep 23, 2010
Plant Regeneration from Seeds, 2022
Journal of Tropical Ecology
Root metrics and plant height for 256 excavated saplings and small trees of 27 species, including... more Root metrics and plant height for 256 excavated saplings and small trees of 27 species, including sown plants, were used to describe belowground structure and assess factors that influence shoot growth in a tropical dry forest (TDF) in Zambia. Models were developed to (i) estimate taproot depth from incomplete excavations and (ii) coarse lateral root biomass from proximal diameter data. The majority of the species studied are slow-growing and had a median height of <200 cm at the age of 16 years. Root development advanced sequentially from taproot elongation to thickening to coarse lateral root development. Shrubs in shallow soil had short taproots with a lower wood density. Plant age explained <10% of the variance in shoot height. Root variables explained the majority of the variance in shoot height. More research is needed to improve our knowledge about how belowground structures influence shoot growth and tree recruitment in TDFs of southern Africa.
International Journal of Environmental Studies, 2011
This book is a contribution by 30 African scientists associated with at least 16 institutions acr... more This book is a contribution by 30 African scientists associated with at least 16 institutions across Africa and a few outside the African Continent working towards solving African resource management problems in the dry forests and woodlands. It is one of the outputs of a CIFOR (Center for International Forestry Research) project, with support from Sida-Natur, on Achieving the Millennium Development Goals in African Dry Forests: From Local Action to National Policy Reforms. Dry forest vegetation (including woodland) is dominated by woody plants, mainly trees, with tree canopy cover over 10 per cent of the ground surface within climates with a dry season of 3 months or more (i.e. areas characterized by frequent droughts, occasional floods and general vulnerability to climate variability). It covers about 17.3 million km 2 in 31 countries in West Africa, East Africa and southern Africa. It is the home of 505 million people, most of whom depend on the dry forests and woodlands for their livelihoods, mainly through rain-fed crop agriculture, livestock farming and gathering of timber and non-timber forest products, which also support local industries. Earlier books on the dry forests and woodlands focused on the Miombo woodlands of southern Africa, but this book covers the entire area of the dry forests in sub-Saharan Africa. The value of the book is the link it provides between the available resources of the dry forests and woodlands, and the use and management of their diverse products and services to contribute to poverty reduction and wealth creation. Chapters 2 to 4 cover the detailed description of the dry forest vegetation types in sub-Saharan Africa in terms of their characteristics, floristic diversity and their potential value to provide products and services. Chapters 5 to 10 address the management practices of the African dry forests and woodlands for specific products and services, and their links with policy, tenure, governance, gender and commercialization. These chapters specifically address non-wood forest products (Chapter 5), timber and other wood products (Chapter 6), firewood and charcoal (Chapter 7), livestock, wildlife and rangelands (Chapter 8), forest plantations and woodlots as a means to create alternative resources (Chapter 9), and, finally, environmental and ecosystem services such as carbon sequestration, soil and water conservation and socio-cultural-spiritual values (Chapter 10). Each individual chapter identifies a number of useful key issues and challenges, and Chapter 11 synthesizes the key issues in the management of the dry forests and woodlands, and suggests the way forward in terms of policy and vii legislative reform, stakeholder participation, resource governance, managing for multiple products and services, and climate and land-use change scenarios. This book provides a current baseline of knowledge on the current resources of the dry forests and woodlands, their use and value, and possible means to manage them towards sustainable development into the future. It poses a challenge to policy-makers and resource managers to make integrated and sustainable resource management a reality to resources users who depend on good governance and the dry forest resources for their livelihoods and prosperity under threats of environmental change.
Agroforestry Systems, 1988
The purpose of natural fallow in bush-fallow cultivaton systems is to improve soil fertility foll... more The purpose of natural fallow in bush-fallow cultivaton systems is to improve soil fertility following a phase of cultivation and to provide useful fores.t products, including livestock feed. When natural fallow fails to serve these purposes, it can be supplemented or 1985/86 planting season (December-February) when 25,100 seedlings of Ecualyptus grandis, Gmelina arborea and Leuceana leucocephala were distributed, free of charge and the programme will continue until 1988. A survey carried out five to seven months after planting revealed that the survival of E. grandis, L. leucocephala and G. arborea seedlings was 65%, 90% and 92%, respectively. The high mortality of E. grandis seedlings was due to termite damage.
Agriculture, Ecosystems & Environment, 2003
There is a growing concern in central and southern Africa about the negative effects of deforesta... more There is a growing concern in central and southern Africa about the negative effects of deforestation caused by shifting cultivation and charcoal production. In the absence of long-term studies that document and assess impacts of tropical deforestation, it is difficult to evaluate the relevance of current policy interventions that address the negative effects of deforestation. To contribute to the knowledge about impacts of tropical deforestation, the effects of clearing Brachystegia-Julbernardia (miombo) woodland on grass biomass and soil nutrient status were assessed at four sites over a 10-years period, from 1991 to 2000 in central Zambia. Woodland clearing increased grass biomass by 20-50% and although its impacts on topsoil organic matter and available phosphorus were apparent, these were not statistically significant. Site and year had the most significant effects on soil nutrient stocks, regardless of the woodland clearing treatment. Generally, fire did not affect grass production but reduced topsoil organic matter and nitrogen at three of the study sites. Deforestation followed by cultivation significantly reduced soil organic matter in the study area. Based on these results, it is recommended that local cultivation practices should incorporate measures that minimize loss of soil organic matter in order to sustain long-term soil fertility.
Miombo woodlands grow on the ancient central African plateau and its escarpments. They form a swa... more Miombo woodlands grow on the ancient central African plateau and its escarpments. They form a swathe across the continent from Angola to Mozambique, and extend from lhnzania and southern Congo in the north, to Zimbabwe in the south. Scientists distin-guish miombo from other savanna woodland and forest formations by the presence of
The designations employed and the presentation of material in this publication do not imply the e... more The designations employed and the presentation of material in this publication do not imply the expression of any opinion whatsoever on the part of the African Forest Forum concerning the legal status of any country, territory, city or area or its authorities, or concerning the delimitation of its frontiers or boundaries regarding its economic system or degree of development. Excerpts may be reproduced without authorization, on condition that the source is indicated. Views expressed in this publication do not necessarily reflect those of the African Forest Forum.
Journal of Plant Ecology, 2008
In spite of the importance of African acacias in vegetation succession and provision of goods and... more In spite of the importance of African acacias in vegetation succession and provision of goods and services, little is known about life-history variations within and among species. Much of the work done on African acacias has focused on seed predation and germination and seedling establishment, especially of Acacia tortilis, Acacia nilotica and Acacia karroo. The primary aim of the present work is to investigate differences in the demography of Acacia polyacantha and Acacia sieberiana and the relationship between life-history characteristics and population size. A secondary objective is to assess how fire, an important ecological factor in savanna vegetation, might modify the growth and demographic dynamics of the two acacias. The study was conducted at the Makeni savanna plot in central Zambia, southern Africa. Seedling emergence from both non-scarified and scarified seeds sown at different times in the wet season and the fate and growth of seedlings and saplings were monitored over a period of 4 years. Annual growth of permanently marked sample trees in annually burnt and fire-protected blocks was recorded over a 6-year period (2002-08) in order to assess inter-specific differences and how fire modifies tree growth patterns. Censuses of natural sap-lings and trees were conducted periodically in sample blocks to determine recruitment into these life-history stages. Seedling emergence and sapling survival rates were much higher in A. sieberiana than in A. polyacantha. However, both seedling and sapling growth rates were higher in A. polyacantha than in A. sieberiana but tree growth rates were similar in the two species. Under fire protection tree growth was significantly influenced by tree size and year while under annual burning only tree size significantly affected tree growth. The dominance of A. sieberiana over A. polyacantha at the study site was attributed to higher seedling emergence rate, higher sapling survival rate and a large sapling bank that forms a reliable source of tree recruitment. The life-history stage characteristics of A. polyacantha suggest that this is an early successional species. Keywords: Acacia d demography d fire d plant growth d survivorship
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Papers by Emmanuel Chidumayo