Miombo Species Research Articles

On the importance of plant phenology in the evaporative process of a semi-arid woodland: could it be why satellite-based evaporation estimates in the miombo differ?

Abstract. The miombo woodland is the largest dry woodland formation in sub-Saharan Africa, covering an estimated area of 2.7–3.6 million km2. Compared to other global ecosystems, the miombo woodland demonstrates unique interactions between plant phenology and climate. For instance, it experiences an increase in the leaf area index (LAI) during the dry season. However, due to limited surface exchange observations in the miombo region, there is a lack of information regarding the effect of these properties on miombo woodland evaporation. It is crucial to have a better understanding of miombo evaporation for accurate hydrological and climate modelling in this region. Currently, the only available regional evaporation estimates are based on satellite data. However, the accuracy of these estimates is questionable due to the scarcity of field estimates with which to compare. Therefore, this study aims to compare the temporal dynamics and magnitudes of six satellite-based evaporation estimates – the Topography-driven Flux Exchange (FLEX-Topo) model, Global Land Evaporation Amsterdam Model (GLEAM), Moderate-Resolution Imaging Spectrometer (MODIS) MOD16 product, operational Simplified Surface Energy Balance (SSEBop) model, Thornthwaite–Mather climatic Water Balance (TerraClimate) dataset, and Water Productivity through Open access of Remotely sensed derived data (WaPOR) – during different phenophases in the miombo woodland of the Luangwa Basin, a representative river basin in southern Africa. The goal of this comparison is to determine if the temporal dynamics and magnitudes of the satellite-based evaporation estimates align with the documented feedback between miombo woodland and climate. In the absence of basin-scale field observations, actual evaporation estimates based on the multi-annual water balance (Ewb) are used for comparison. The results show significant discrepancies among the satellite-based evaporation estimates during the dormant and green-up and mid-green-up phenophases. These phenophases involve substantial changes in miombo species' canopy phenology, including the co-occurrence of leaf fall and leaf flush, as well as access to deeper moisture stocks to support leaf flush in preparation for the rainy season. The satellite-based evaporation estimates show the highest agreement during the senescence phenophase, which corresponds to the period of high temperature, high soil moisture, high leaf chlorophyll content, and highest LAI (i.e. late rainy season into the cool-dry season). In comparison to basin-scale actual evaporation, all six satellite-based evaporation estimates appear to underestimate evaporation. Satellite-based evaporation estimates do not accurately represent evaporation in this data-sparse region, which has a phenology and seasonality that significantly differ from the typical case in data-rich ground-truth locations. This may also be true for other locations with limited data coverage. Based on this study, it is crucial to conduct field-based observations of evaporation during different miombo species phenophases to improve satellite-based evaporation estimates in miombo woodlands.

Lipophilic and polar extracts in the cork-rich bark of the Miombo species Parinari curatellifolia

Lipophilic and polar extracts in the cork-rich bark of the Miombo species Parinari curatellifolia

Floristic Diversity and Natural Regeneration of Miombo Woodlands in the Rural Area of Lubumbashi, D.R. Congo

Increased anthropogenic pressure on forest resources leads to deforestation and forest degradation, significantly limiting the regeneration capacity of native woody species and consequently the restoration of miombo woodlands in anthropized habitats within the rural area of Lubumbashi. This study assessed miombo species’ diversity and natural regeneration capacity through floristic inventories in three different habitats (unexploited forests, degraded forests, and post-cultivation fallows). The results reveal that for the adult stratum, unexploited and degraded forests exhibit higher dendrometric (density, mean square diameter, basal area) and floristic parameter (taxa, genera, families) values compared to post-cultivation fallows. Furthermore, the regeneration of miombo woody species is higher in degraded forests (21 taxa; 105 juveniles/plot). However, regarding the sapling’s stratum (1 cm ≤ dbh < 10 cm), the three habitats display similar situations. Additionally, the floristic composition and diversity of unexploited and degraded forests show a significantly higher similarity (76.50%) among them compared to these habitats and the post-cultivation fallows (56.00%). These findings indicate that miombo woodlands have the potential to regenerate and maintain floristic diversity even in anthropized habitats, particularly in degraded forests. To sustain this natural regeneration capacity of miombo woody species and promote the restoration of forest cover and its floristic diversity, it is imperative to determine the rotation period after habitat exploitation and regulate anthropogenic activities and late bush fires, particularly in anthropized habitats at the village level.

Assessing structure, spatial patterning, and size class distribution of miombo woodland species along a precipitation gradient

Our study investigates the intricate ecological mechanisms shaping miombo woodlands across a rainfall gradient in Zimbabwe. We comprehensively analysed vegetation structure, tree morphology, and spatial patterning across three distinct ecological regions characterized by varying mean annual precipitation (MAP). Results reveal that taller and larger trees are prevalent in the more humid site, while higher tree density is observed in the drier site. The spatial analysis highlights a significant aggregation of adult miombo species across all sites, with juveniles exhibiting a propensity to cluster around adult trees. These findings underscore the pivotal role of ecological gradients, such as precipitation, in shaping miombo woodland structure. However, the absence of clear spatial patterns across the rainfall gradient suggests that precipitation may have less influence on the spatial distribution of miombo trees. Understanding these complex ecological dynamics is essential for developing targeted conservation and management strategies that align with the unique attributes of miombo woodlands, critical ecosystems within the African landscape particularly vulnerable to global climate change.

Cork cellular and chemical features underlying bark environmental protection in the miombo species Parinari curatellifolia

Parinari curatellifolia is an important evergreen tree from the Miombo woodland of south-central and eastern Africa. The bark is corky, suggesting an increased protection against the ecosystem high temperatures and drought conditions as well as against wild fires. The cork in the bark rhytidome of P. curatellifolia was analyzed here for the first time with a focus on chemical and cellular features. P. curatellifolia cork has the cellular characteristics of cork tissues, with typical honeycomb structure in the tangential section and a brick-wall layer in the transverse and radial sections, without intercellular voids. Chemically P. curatellifolia cork has 8.4 % extractives, 33.9 % suberin, 31.9 % lignin and 25.2 % polysaccharides of the cork. The hemicelluloses are mostly xylans, with a substantial proportion of arabinose and galactose. Suberin showed a proportion of long chain lipids to glycerol (LCLip:Gly, mass ratio) of 8.5, and the long chain monomeric composition included a similar proportion of α,ω-diacids and ω-hydroxy acids (35.4 % and 31.5 % of long chain monomers) with a substantial proportion of monoacids (19.4 % of long chain monomers). Lignin is a guaiacyl-syringyl lignin with S/G of 0.32 and H:G:S of 1:14.1:4.5. The rhytidome composition and the cellular and chemical features of its cork are in line with environment-targeted protective features namely as a transpiration and insulation barrier, and as an increased fire protection.

Plant defences as functional traits: A comparison across savannas differing in herbivore specialization

Abstract Top‐down and bottom‐up forces in tropical savannas have shaped the evolution of traits that enable plants to thrive in environments where soils are poor, dry seasons are long, fire is frequent, woody plants and grasses compete and herbivores range from cryptic caterpillars to elephants that topple entire trees. African savannas and the South American cerrado have similar climates and fire regimes, but differ in the presence of large mammal herbivores, which are mostly extinct in the cerrado. These biomes offer an instructive comparison to understand how plant defence traits evolved in response to differential herbivore pressure. Within Africa, mammalian herbivore pressure also differs across savannas, being lower in the miombo relative to more open, mixed savannas. The dominance of specialist insect herbivores in the cerrado, relative to the more generalist mammalian herbivores in Africa, suggests that defence traits will differ between savannas in accordance with herbivore identity and pressure. Wood is densest in mixed African savannas, as expected because large mammals often damage trees. Specific leaf area, related to palatability, is higher in mixed African savannas and the cerrado relative to the miombo, while leaf N is surprisingly higher in miombo species. Ant mutualists are important defences in mixed African savannas and the cerrado. Defensive chemistry has received less attention in the trait literature. Foliar phenolics, the most commonly studied chemical defences in savannas, vary in their efficacy. New analyses isolating specific compounds are informative as is the evaluation of phytochemical diversity as a defence. There are indications that phytochemical defences are more diverse in the cerrado, which may be related to greater specialization of cerrado herbivores. Synthesis. The dominance of specialist insect herbivores in the cerrado, relative to generalist mammalian herbivores in Africa, selected for different plant defence traits, contributing to the separation of species along the leaf economics spectrum and demonstrating the importance of plant defences as plant functional traits. African savanna species seem to follow a more acquisitive strategy, followed by miombo species. Cerrado species appear to follow a more conservative strategy with greater investments in tough leaves and chemical defences.

Linking Bacterial Rhizosphere Communities of Two Pioneer Species, Brachystegia boehmii and B. spiciformis, to the Ecological Processes of Miombo Woodlands

Miombo is the most extensive ecosystem in southern Africa, being strongly driven by fire, climate, herbivory, and human activity. Soils are major regulating and supporting services, sequestering nearly 50% of the overall carbon and comprising a set of yet unexploited functions. In this study, we used next-generation Illumina sequencing to assess the patterns of bacterial soil diversity in two pioneer Miombo species, Brachystegia boehmii and Brachystegia spiciformis, along a fire gradient, in ferric lixisol and cambic arenosol soils. In total, 21 phyla, 51 classes, 98 orders, 193 families, and 520 genera were found, revealing a considerably high and multifunctional diversity with a strong potential for the production of bioactive compounds and nutrient mobilization. Four abundant genera characterized the core microbiome among plant species, type of soils, or fire regime: Streptomyces, Gaiella, Chthoniobacter, and Bacillus. Nevertheless, bacterial networks revealed a higher potential for mutualistic interactions and transmission of chemical signals among phylotypes from low fire frequency sites than those from high fire frequency sites. Ecological networks also revealed the negative effects of frequent fires on the complexity of microbial communities. Functional predictions revealed the core “house-keeping” metabolisms contributing to the high bacterial diversity found, suggesting its importance to the functionality of this ecosystem.

Aboveground and belowground tree biomass and carbon stocks in the miombo woodlands of the Copperbelt in Zambia

Globally, belowground biomass (BGB) accounts for 20–26% of total biomass, and as such it is an important carbon (C) pool for many vegetation types. However, large uncertainty exists for belowground biomass C compared to aboveground stocks. Using data from 108 destructively harvested trees belonging to 36 miombo species, we estimated root to shoot ratios, and developed models for estimation of aboveground biomass (AGB), BGB and total biomass C stocks in the Copperbelt province of Zambia. We also validated our models using independent datasets from elsewhere in Zambia and Malawi. The C fractions in wood ranged between 51.9 and 58.9%, which was higher than the IPCC default value. The root to shoot ratio was found to be 0.303. The analysis also demonstrated isometric scaling of BGB with AGB. According to cross-validation results, the model that incorporated wood density (ρ), diameter at breast height (D) and total stem height (H) formulated as AGB =0.093(ρD2H)0.97 *1.08 outperformed existing models developed for the miombo woodlands in Zambia. The best model for BGB was BGB = 0.476(AGB)0.88*1.126. Using the top-ranked models, the stand-level AGB stocks were estimated at 222.2 Mg ha−1, while BGB stocks were estimated at 52.4 Mg ha−1. Aboveground and belowground C stocks were 125.3 Mg ha−1 and 29.5 Mg ha−1, respectively. Total biomass C stocks were estimated at 152.1 Mg ha−1 or 558.3 Mg ha−1 CO2 equivalent sequestered in tree biomass. These estimates may be used as baseline data for future carbon management and for emerging payment for ecosystem services projects in miombo woodlands.

Characterization of Miombo species used by rural communities as fuelwood in Northern Mozambique

ABSTRACT The rural population of Mozambique has a strong preference for using native tree species for fuelwoods instead of Eucalyptus wood. The reforestation projects failed to respond to the wishes of consumers who considered eucalyptus wood to be low quality compared to the native species traditionally used by the population. The present study aimed to determine the wood characteristics of Miombo woodland species which are often used as an energy source in Sanga district, northern Mozambique, and then compare the results with those found in the literature on Eucalyptus species used for the same purpose. Chemical, physical, energetic, and thermal properties were analyzed. Among all studied species, U. kirkiana and J. globiflora presented high quality of wood for energy purposes, in Northern Mozambique. These species showed high basic density and extractive contents, which are the characteristics responsible for providing high energy density, longer wood combustion duration, and higher combustion intensity. These last three characteristics are considered of greater importance for the choice of fuelwood by the communities when compared to the Eucalyptus. The Eucalyptus are fast-growing species and are recommended for selecting genotypes with high energy density and favorable combustion parameters in order to introduce new energy planting programs in Mozambique to guarantee the wood supply in a short time and the conservation of natural resources.

Species-specific biomass allometric models and expansion factors for indigenous and planted forests of the Mozambique highlands

Secondary Miombo woodlands and forest plantations occupy increasing areas in Mozambique, the former due to anthropogenic activities. Plantations, mainly species of Eucalyptus and Pinus, are being established on sites previously covered by secondary Miombo woodlands. This affects the evolution, cycle and spatiotemporal patterns of carbon (C) storage and stocks in forest ecosystems. The estimation of C storage, which is indispensable for formulating climate change policies on sequestrating CO2, requires tools such as biomass models and biomass conversion and expansion factors (BCEF). In Mozambique, these tools are needed for both indigenous forests and plantations. The objective of this study is to fit species-specific allometric biomass models and BCEF for exotic and indigenous tree species. To incorporate efficient inter-species variability, biomass equations were fitted using nonlinear mixed-effects models. All tree component biomass models had good predictability; however, better predictive accuracy and ability was observed for the 2-predictors biomass model with tree height as a second predictor. The majority of the variability in BCEF was explained by the variation in tree species. Miombo species had larger crown biomass per unit of stem diameter and stored larger amounts of biomass per stem volume. However, due to relatively rapid growth, larger stem diameters, heights, and stand density, the plantations stored more biomass per tree and per unit area.

Predicted long-term effects of decomposition of leaf litter from Pinus taeda, Eucalyptus cloeziana and deciduous miombo trees on soil carbon stocks

Decomposition rate of leaf litter in native miombo and in Pinus taeda and Eucalyptus cloeziana plantations was measured in the Inhamacari forest research area, Manica province, Mozambique. The Q-model and a simple first-order exponential decomposition model (K-model) were used to predict long-term accumulation of carbon (C) in the litter layer and in soil 34 years after plantation establishment and at steady-state. Measured litterfall from the study plots was used to estimate litter inputs for prediction of C stocks. The results were compared with measured C stocks when stand age in the first-rotation plantation stands was approx. 34 years.At the end of the one-year decomposition study, about half or less of the initial litter mass remained. Leaf litter of the miombo species Brachystegia spiciformis decomposed faster than leaf litter of non-native Eucalyptus cloeziana and Pinus taeda, and a representative mixture of leaf litters of dominating miombo trees decomposed faster than P. taeda, but not E. cloeziana.Measurements indicated higher soil temperatures, and thus higher microbial growth rate, in miombo than in plantation stands. Estimates of initial leaf litter quality indicated higher decomposability of mixed litter substrates of miombo stands than P. taeda needles.Assuming current measured litterfall, the accumulated C stocks predicted by the Q-model were higher than measured C stocks in the litter layer. A major cause of the discrepancy between predicted and measured C stocks in the litter layer of miombo stands was probably frequent ground fires and probably also the influence of termites and other modes of transport into the soil profile.Previously measured increase in C stocks in the soil (0–50 cm) and the litter layer of first-rotation stands of P. taeda and E. cloeziana plantations were much larger than the Q-model predicted soil C stocks at steady-state, indicating that this increase cannot be explained by leaf litter input only.

Dynamic Patterns of Trees Species in Miombo Forest and Management Perspectives for Sustainable Production—Case Study in Huambo Province, Angola

This paper aims to assess important forest parameters, including tree density, diameter at breast height (DBH), and age distribution, investigate the dynamic growth of miombo tree species, and employ this information to design a management framework in miombo forests. The delineation of the management zones was based on unsupervised land cover classification that began with three zones where ground data was collected and increased to five zones. Eighteen circular plots (25.2 m radius) were randomly distributed over the study areas to assess the current situation and potential growth patterns for each species. The patterns of the six most representative tree species of miombo in Angola were described and we used KORFiT 2.4 software to fit data and develop growth curves for at least three miombo species. Growth function fitness was evaluated by root mean squared error (RMSE), coefficient of determination (R2), significance of the parameters (p < 0.05), and Akaike’s information criterion (AIC). The diameter distribution of miombo tree species resembled a typical distribution of uneven-aged forest stands; higher DBH classes had lower abundances of tree species. Logistic and Gompertz growth functions were the best fits for miombo tree species. Brachystegia spiciformis Benth., is suggested as a potential species for timber management in the region because they displayed high growth potential to more quickly reach an assumed minimum DBH of 20 cm. This study concluded that miombo forest stands present an irregular structure in which DBH distribution illustrated only two patterns: many small stems and a bimodal forest structure.

Effects of 34-year-old Pinus taeda and Eucalyptus grandis plantations on soil carbon and nutrient status in former miombo forest soils

There is a strong need in Mozambique to counteract decades of deforestation and forest degradation by planting new forests. Plantations of Pinus/Eucalyptus species and maintenance of mature miombo forests are activities supported by the REDD+ mechanism (Reducing Emissions from Deforestation and forest Degradation) in climate negotiations. This study examined the effects of first-rotation P. taeda L. (Loblolly pine) and E. grandis Hill ex Maiden plantations (ca. 34 years old) on soil carbon status compared with adjacent dry miombo forest. At three study sites located in the Western Highlands of Manica Province, Mozambique, study plots with Pinus taeda, Eucalyptus grandis and mixed-deciduous miombo species were delineated. The selection criteria were (i) forest stand of first-rotation plantation of Pinus/Eucalyptus, located adjacent to miombo forest, (ii) plantations established on soils similar to miombo forest soils, and (iii) former land use similar to that at current miombo sites. Stocks of soil organic carbon (SOC), total nitrogen (N) and extractable phosphorus (P) were quantified. Soil pH (H2O), cation exchange capacity (CEC) and base saturation (BS) were measured in soil extracted with ammonium acetate.Plantations of P. taeda and E. grandis increased total SOC stocks (0–50 cm) and N stocks in the top 10 cm. Assuming steady state in the miombo stands, the estimated net stock change in soil carbon was 1.41 Mg ha−1 yr−1 in P. taeda and 1.53 Mg ha−1 yr−1 in E. grandis stands. Estimated N accumulation rate was 32 kg ha−1 yr−1 in P. taeda and E. grandis stands. P. taeda had no significant effect on extractable P, soil pH and BS, but had significantly higher. CEC compared with miombo forest soil. E. grandis decreased P stocks, but increased soil pH and BS.Overall, P. taeda and E. grandis plantation had a large impact on SOC in dry miombo forest and also affected soil acidity and soil nutrient status, except for total soil N stocks. These effects of tree plantation on soil reflected differences in management practices between miombo forest and plantations, with the latter being subjected to better protection against fires and illegal cutting.

Miombo woodland under threat: Consequences for tree diversity and carbon storage

Agriculture is expanding rapidly in the miombo woodlands of sub-Saharan Africa. Clear felling results in the loss of species and ecosystem services. The remaining woodland is used as a vital support system for the farming communities, and the impact of this utilisation on biodiversity and ecosystem service provision is not clear. Understanding these effects will aid the development of effective, sustainable land management strategies for multiple outcomes, including biodiversity conservation and resource utilisation. This study provides new data on miombo woodland tree species diversity, structure and carbon storage from a 8766km2 landscape in south-western Tanzania, which is undergoing rapid conversion to tobacco cultivation.Human utilisation of the woodland was classified by ground surveys which recorded evidence of use (e.g. cut poles and timber, removal of bark and roots, access routes). Nine sites were surveyed and categorised into three groups: high, medium and low utilisation. To determine the effect of utilisation on the tree community stem density, diameter at breast height, tree species richness and carbon storage were recorded. In the low utilisation sites carbon storage was similar to that found in other miombo woodlands (28tHa−1), and the Shannon Wiener diversity score for tree species diversity was 3.44. However, in the high utilisation sites, tree species diversity (2.86) and carbon storage declined (14.6tHa−1). In areas of moderate utilisation diversity and carbon storage were maintained, but the structure of the woodland was affected, with a reduction of Class 1 (Diameter at Breast Height (DBH)<10cm) stems, demonstrating low recruitment which leads to a reduction in sustainability. Tree species richness and abundance demonstrated an intermediate disturbance effect in relation to utilisation, with highest levels at medium utilisation sites.Key miombo woodland species from the subfamily Caesalpinioideae in the two genera Brachystegia and Julbernardia were present in all sites, but the frequency of Brachystegia species declined by 60% from low to high utilisation. The IUCN near-threatened timber species Pterocarpus angolensis, highly protected in Tanzania, was harvested throughout the study site, and the majority of trees recorded were immature (DBH⩽20cm), suggesting that it is commercially extinct for the foreseeable future.These findings illustrate that in miombo woodlands with low to medium utilisation levels key miombo species are retained, and tree species diversity and carbon storage remains optimal. Sustainable land management plans need to regulate utilisation within miombo landscapes and retain areas of woodland. This will ensure their long term viability, and continue to support the 100million people who are reliant on miombo woodlands for their goods and services.

Regeneration dynamics of miombo woodland in response to different anthropogenic disturbances: forest characterisation for sustainable management

Miombo woodland, the most extensive vegetation formation in Africa, recovers well after cessation of disturbances from different land use practices on a site. The core strategy of sustainable miombo woodland management requires a detailed understanding of the implications of land use practices such as charcoal production, slash & burn agriculture and timber harvesting, on miombo woodland dynamics. The study undertook a comparative analysis of the influence of charcoal production, slash & burn agriculture and timber harvesting on woodland recovery at population and stand levels. Sites of known age after abandoning a specific land use were selected where the land uses were practiced in close proximity to each other. This involved characterizing miombo woodland based on some selected dominant species through developing stem diameter class distribution profiles. Most species in charcoal and slash & burn regrowth stands showed gradual development from one size class to another with this development being significantly (P < 0.0005) influenced by species rather than the disturbance category. The reason is that the key miombo species are light demanding and require maximum exposure to sunlight to grow fast. By contrast, species in single-tree harvested stands exhibited static stem diameter class profiles with no individuals in certain classes. The study concludes that whilst single-tree selection timber harvesting appears to show that the forest is intact at the stand level, it is actually not a sustainable management option at population level. It also concludes that charcoal production and slash & burn agriculture are necessary disturbances that enhance the establishment and development of the regeneration pool of the miombo woodland species.

Xylem cavitation vulnerability influences tree species’ habitat preferences in miombo woodlands

Although precipitation plays a central role in structuring Africa's miombo woodlands, remarkably little is known about plant-water relations in this seasonally dry tropical forest. Therefore, in this study, we investigated xylem vulnerability to cavitation for nine principal tree species of miombo woodlands, which differ in habitat preference and leaf phenology. We measured cavitation vulnerability (Ψ(50)), stem-area specific hydraulic conductivity (K S), leaf specific conductivity (K L), seasonal variation in predawn water potential (Ψ(PD)) and xylem anatomical properties [mean vessel diameter, mean hydraulic diameter, mean hydraulic diameter accounting for 95 % flow, and maximum vessel length (V L)]. Results show that tree species with a narrow habitat range (mesic specialists) were more vulnerable to cavitation than species with a wide habitat range (generalists). Ψ(50) for mesic specialists ranged between -1.5 and -2.2 MPa and that for generalists between -2.5 and -3.6 MPa. While mesic specialists exhibited the lowest seasonal variation in Ψ(PD), generalists displayed significant seasonal variations in Ψ(PD) suggesting that the two miombo habitat groups differ in their rooting depth. We observed a strong trade-off between K S and Ψ(50) suggesting that tree hydraulic architecture is one of the decisive factors setting ecological boundaries for principal miombo species. While vessel diameters correlated weakly (P > 0.05) with Ψ(50), V L was positively and significantly correlated with Ψ(50). Ψ(PD) was significantly correlated with Ψ(50) further reinforcing the conclusion that tree hydraulic architecture plays a significant role in species' habitat preference in miombo woodlands.

Genetic diversity of Brachystegia boehmii Taub. and Burkea africana Hook. f. across a fire gradient in Niassa National Reserve, northern Mozambique

Miombo woodlands constitute the most important type of vegetation in southern Africa, covering about 70% of the Zambezian phytoregion. This ecosystem, dominated by the genera Brachystegia , Julbernardia and Isoberlinia , has an immeasurable socio-economic and environmental value, playing a key role in formal and informal economies and in energy, water and carbon balances. Anthropogenic fires represent one of the major threats, compromising the stability of miombo. In this study we report on the usefulness of ISSR markers to assess, for the first time, the genetic diversity in two typical miombo species, Brachystegia boehmii Taub. and Burkea africana Hook. f. across a fire gradient in the Niassa National Reserve (NNR). According to our data, ISSR seem to be a suitable molecular marker's system for biodiversity studies in both species, generating high levels of polymorphisms coupled with a convenient resolving power. The results point to a link between fire-tolerance and genetic diversity, as judged by the higher diversity levels observed in B. africana (fire-tolerant) and by the evolutive fire response of B. boehmii . Although fire differentially affects the biodiversity in each species, in general, the overall genetic diversity was high and their survival does not seem to be compromised by the frequency of fires, agreeing with the fact that NNR is one of the least disturbed areas of deciduous miombo. ► We report on the assessment of the genetic diversity in two miombo species. ► There is a correlation between fire-tolerance and genetic diversity. ► There is a good genetic potential for Burkea africana and Brachystegia boehmii. ► The current fire frequency is affecting differently miombo species.

The influence of stump diameter and height on coppicing ability of selected key Miombo woodland tree species of Zambia: A guide for harvesting for charcoal production

A study was undertaken to investigate the influence of stump diameter and stump height on the coppice effectiveness in relation to interspecific variation. The overall objective was to provide an understanding of the coppicing ability of the selected key miombo species in order to provide a basis for sustainable management of the species. A total of 102 stumps were observed. Coppice effectiveness results varied among the key tree species withBrachystegia longifolia and Isoberlinia angolensis having the highest number of coppice shoots (9.8 ± 2.6) and 7.5 ± 1.6) and the least being Julbernadia paniculata (4.2 ± 1.3). High coppice effectiveness indicates a greater recruitment potential for miombo species. The study has revealed that the coppicing ability of miombo trees is species dependent. The results therefore suggest that management of miombo species should be species specific rather than holistic. The research has also provided a model for planning when cutting of the aforementioned miombo species for charcoal production in terms of the diameter classes that provide high coppice effectiveness. Key words: Coppice effectiveness, sustainable management, regeneration.

The role of the Miombo Woodlands of the Southern Highlands of Tanzania as carbon sinks

-1 . Of the total carbon, 40 and 60% was contributed by stems and branches respectively. Different species contributed differently to carbon stocks in these ecosystems with Brachystegia spiciformis and Julbernardia globiflora contributing the most. The estimated carbon stocks in this ecosystem is within the range observed in dry forests elsewhere though they are in their early stages of regeneration after extensive exploitation pressure. Under proper management there is a tremendous capacity for carbon storage in these Miombo woodlands to mitigate carbon emissions. Since Miombo species tend to invest much in roots an assessment of below ground carbon in roots can add to the carbon storage potential of these ecosystems. Evaluation of the root and soil carbon in these ecosystems is important in determining the full potential of these ecosystems to act as carbon sink.

Age and growth rate determination using growth rings of selected miombo woodland species in charcoal and, slash and burn regrowth stands in Zambia

The field of dendrochronology has not been widely applied in tropical species because many scientists generally perceive that such species rarely produce distinct growth rings. This study was undertaken to determine if the key Miombo species produce distinct growth rings and to determine the relationship between the number of growth rings and age of the tree and stem diameter. The results showed a high correlation between number of growth rings and stand age for both charcoal (P < 0.001, r = 0.9246) and slash and burn (P < 0.001, r = 0.9019) regrowth stands. Additionally, the study has revealed high mean annual ring width values ranging from 4.4 to 5.6 mm in both charcoal and slash and burn regrowth stands. The pattern of ring development per year and the mean annual ring width values provide a basis for the use of ring counts in determining the age of Miombo regrowth stands and predicting the merchantable age for key Miombo woodland species. The results can therefore be used in planning the cutting cycles in Miombo woodlands. However, the phenomenon of missing growth rings suggests that the influence of environment in the use of growth rings in age determination need to be considered in areas that experience droughts. Key words: Growth rates, growth rings, slope, diameter at breast height and cutting rotations.