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Forest–woodland–savannah mosaics are a common feature in the East African landscape. For the conservation of the woody species
that occur in such landscapes, the species patterns and the factors that maintain it need to be understood. We studied the
woody species distribution in a forest–woodland–savannah mosaic in Budongo Forest Reserve, Uganda. T...
Contexts in source publication
Context 1
... DCA analysis on combined and trimmed data (491 plots and 45 species) ordered the plots mainly along 1 axis (Figure 3a). This axis had a relatively high eigenvalue (0.465) suggesting significant woody species variation along this axis. ...
Context 2
... species plot (Figure 3b) also shows most of the variation along the first axis. The effect of the second axis is only evident close to zero along axis 1, the forest side, where there appear to be two groups (the same can be said for the plot scores). ...
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... effect of the second axis is only evident close to zero along axis 1, the forest side, where there appear to be two groups (the same can be said for the plot scores). Based on this interpretation the species can be divided into three groups; A, B and C (Figure 3b). Groups A and B occur within the forest area and group C, probably starting at the forest edge, stretches through to the woodland area. ...
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... of the species identified as belonging to groups A and B e.g. Cynometra alexandri, Khaya anthotheca, Diospyros abyssinica, Uvariopsis congensis and Holoptelea grandis ( Figure 3b) were also identified through indicator species analysis as good indicators for the No-fire class. Of these, Diospyros abyssinica, Uvariopsis congensis, Holoptelea grandis and all Celtis species were also good indicators of the forest class (Appendix 2). ...
Context 5
... always starts with very few species, then progresses awhile along one line with more species coming in as conditions become more favorable (Huston 1994). In our study, few species were observed in the wooded grassland end of the gradient and species numbers increased as one moved towards the forest (Figure 3b). Although the forest side of the gradient had more species, other species occur away from the forest environment. ...
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... It makes sense to improve our knowledge of the dynamics taking place naturally in absence of direct human impacts, prior to launching vast, costly, possibly damaging and ultimately uncertain national afforestation programs. In Africa, forest and savanna are the dominant biomes covering respectively 11% and 34% of the land surface of the continent (Nangendo et al., 2006;Parr et al., 2014) and accounting for more than 60% of terrestrial productivity (Beer et al., 2010). Several studies, scattered from Guinea to the Central African ...
... Previous efforts have been either samplebased or employed coarse spatial resolution data (Youta-Happi, 1998;Youta-Happi et al., 2003;Cuni-Sanchez et al., 2016;Deklerck et al., 2019) owing to the challenges of maintaining sampling over long periods combined with the inherent constraints of field data collection which do not consider the whole variability of the landscape. Remote sensing (RS) therefore has a great potential for use in mapping biodiversity (Broadbent et al., 2008;Hill, 2013;Féret and Boissieu, 2020), biomass (Bastin et al., 2014;Kumar et al., 2015;Pandit et al., 2018;Forkuor et al., 2019) and periodical phenomena i.e. fires (Nangendo et al., 2006;Miller and Thode, 2007;Escuin et al., 2008;Sunderman and Weisberg, 2011;Chen et al., 2017) with continuous spatial coverage over large geographic areas. More recent satellite constellations carrying passive optical sensors (notably Sentinel 2; 10 m; Planet; 3.7 m) of improved temporal, spectral and spatial resolutions allow more detailed characterizations of compositional gradients in the vegetation, notably in terms of the abundance of broad functional/optical plant types. ...
Understanding the effects of global change (combining anthropic and climatic pressures) on biome distribution needs innovative approaches allowing to address the large spatial scales involved and the scarcity of available ground data. Characterizing vegetation dynamics at landscape to regional scale requires both a high level of spatial detail (resolution), generally obtained through precise field measurements, and a sufficient coverage of the land surface (extent) provided by satellite images. The difficulty usually lies between these two scales as both signal saturation from satellite data and ground sampling limitations contribute to inaccurate extrapolations. Airborne laser scanning (ALS) data has revolutionized the trade-off between spatial detail and landscape coverage as it gives accurate information of the vegetation’s structure over large areas which can be used to calibrate satellite data. Also recent satellite data of improved spectral and spatial resolutions (Sentinel 2) allow for detailed characterizations of compositional gradients in the vegetation, notably in terms of the abundance of broad functional/optical plant types. Another major obstacle comes from the lack of a temporal perspective on dynamics and disturbances. Growing satellite imagery archives over several decades (45 years; Landsat) and available computing facilities such as Google Earth Engine (GEE) provide new possibilities to track long term successional trajectories and detect significant disturbances (i.e. fire) at a fine spatial detail (30m) and relate them to the current structure and composition of the vegetation. With these game changing tools our objective was to track long-term dynamics of forest-savanna ecotone in the Guineo-Congolian transition area of the Central Region of Cameroon with induced changes in the vegetatio structure and composition within two contrasted scenarios of anthropogenic pressures: 1) the Nachtigal area which is targeted for the dam construction and subject to intense agricultural activities and 2) the Mpem et Djim National Park (MDNP) which has no management plan. The maximum likelihood classification of the Spot 6/7 image aided with the information from the canopy height derived from ALS data discriminated the vegetation types within the Nachtigal area with good accuracy (96.5%). Using field plots data in upscaling aboveground biomass (AGB) form field plots estimates to the satellite estimates with model-based approaches lead to a systematic overestimation in AGB density estimates and a root mean squared prediction error (RMSPE) of up to 65 Mg.ha−1 (90%), whereas calibration with ALS data (AGBALS) lead to low bias and a drop of ~30% in RMSPE (down to 43 Mg.ha−1, 58%) with little effect of the satellite sensor used. However, these results also confirm that, whatever the spectral indices used and attention paid to sensor quality and pre-processing, the signal is not sufficient to warrant accurate pixel wise predictions, because of large relative RMSPE, especially above (200–250 Mg.ha−1). The design-based approach, for which average AGB density values were attributed to mapped land cover classes, proved to be a simple and reliable alternative (for landscape to region level estimations), when trained with dense ALS samples. AGB and species diversity measured within 74 field inventory plots (distributed along a savanna to forest successional gradient) were higher for the vegetation located in the MDNP compared to their pairs in the Nachtigal area. The automated unsupervised long-term (45 years) land cover change monitoring from Landsat image archives based on GEE captured a consistent and regular pattern of forest progression into savanna at an average rate of 1% (ca. 6 km².year-1). No fire occurrence was captured for savanna that transited to forest within five years of monitoring. Distinct assemblages of spectral species are apparent in forest vegetation which is consistent with the age of transition. As forest gets older AGBALS recovers at a rate of 4.3 Mg.ha-1.year-1 in young forest stands (< 20 years) compared to 3.2 Mg.ha-1.year-1 recorded for older forest successions (≥ 20 years). In savannas, two modes could be identified along the gradient of spectral species assemblage, corresponding to distinct AGBALS levels, where woody savannas with low fire frequency store 50% more carbon than open grassy savannas with high fire frequency. At least two fire occurrences in five years is found to be the fire regime threshold below which woody savannas start to dominate over grassy ones. Four distinct plant communities were found distributed along a fire frequency gradient. However the presence of fire-sensitive pioneer forest species in all scenarios of fire frequencies (from low to high fire frequencies) would suggest that the limiting effect of fire on woody vegetation is not sufficient to hinder woody encroachment in the area bringing therefore sufficient humidity required for the establishment of pioneer forest saplings within open savannas. These results have implications for carbon sequestration and biodiversity conservation policies. The maintenance of the savanna ecosystem in the region would require active management actions, and contradicts reforestation goals (REDD+, Bonn challenge, etc.).
... Furthermore, in many African-protected areas, forest, woodland and savanna vegetation types coexist, and fire management should accommodate this variation. For example, Nangendo et al. (2006) proposed that forest landscapes in the Budongo Forest Reserve, Uganda, should not be burned, whilst the adjacent wooded grassland should be burnt regularly. Similarly, a variety of approaches were recommended for Murchison Falls National Park, Uganda, because of the large variety of vegetation types (Nangendo et al. 2005). ...
The level of understanding of the ecological effects of fires has improved over the past century, but comprehensive information on the practical application of fire remains restricted to a few well-studied areas, and management information is scattered. This article reviews the goals of fire management practices in African savanna-protected areas, and the approaches that have been adopted to achieve them. We identified 15 distinct fire management practices described in 107 papers from 19 African countries. Fire management has evolved in response to changing ecological understanding, as well as the shifting goals of protected areas. Currently, fire management practices can be divided into those that use fire to achieve specific ecological outcomes, those where fire is applied to promote diverse fire patterns across the landscape without necessarily having a specific ecological outcome in mind, and those that use fire to achieve specific, non-ecological or social goals. In larger, heterogeneous protected areas, fire management practices may vary at different sites in order to achieve a range of goals. We compared the effectiveness of each practice in terms of achieving 10 broad goals. These included ecological goals, for example, reversing woody and social goals (e.g. maintaining community relationships).
Conservation implications: Fire management remains an important ecosystem process that can be manipulated to achieve particular goals in protected areas. The choice of a particular approach, or approaches, will depend on the circumstances pertaining to a particular protected area, and we provide examples of situations where each practice could be most appropriate.
... Any fire Ngorongoro Crater, Tanzania Trollope et al., 2003) Madikwe WR, South Africa Serengeti NP, Tanzania Sioma-Ngwezi NP, Zambia (Trollope & Trollope, 2010) Kruger NP, South Africa (Biggs & Potgieter, 1999;Parr et al., 2009;Smit et al., 2013;van Wilgen et al., 2003van Wilgen et al., , 2007van Wilgen et al., , 2014 North-West Province, South Africa Kasanka NP, Zambia (Eriksen, 2007) Soudan savanna belt, Mali Budongo FR, Uganda (Nangendo et al., 2005(Nangendo et al., , 2006 Africa ( Siegfried, 1981;Stander et al., 1993) Kruger NP, South Africa (Biggs & Potgieter, 1999;Trollope et al., 1995;van Wilgen et al., 2003van Wilgen et al., , 2007 Chyulu Hills NP, Kenya (Kamau & Medley, 2014) Kasanka NP, Zambia (Eriksen, 2007) Sub-Saharan Africa (Goldammer & De Ronde, 2004) West Africa (Hough, 1993) Ankarafantsika NR, Madagascar (Kull, 2002) Kavango-Zambezi TCA Zimbabwe and Mozambique ( Serengeti NP, Tanzania Stronach, 1988) Madikwe GR, South Africa (Hudak, 1999) Avoid using scarce resources to manage a process that is not harmful ...
... For example, Nangendo et al., (2006) proposed that forest landscapes in the Budongo Forest Reserve, Uganda, not be burned at all, while the adjacent wooded grassland should be burnt regularly. Similarly, a variety of approaches were recommended for Murchison Falls National Park, Uganda, due to the large variety of vegetation types (Nangendo et al., 2005), and te Beest et al. (2012) recommended selective fire suppression in riverine vegetation and margins of scarp forests to protect fire-sensitive endemic species. ...
... Contrasting vegetation types often co-exist within the same PAs, and different plant communities may require different approaches to fire management (Nangendo, Steege, & Bongers, 2006). Effective management thus cannot occur without vegetation descriptions at a scale appropriate for the intended management purpose. ...
Fire is an important process that shapes the structure and functioning of African savanna ecosystems, and frequently occurs as either prescribed burns or unintentional wildfires in protected areas. Though the level of understanding of the ecological effects of fires has grown substantially over the past century, comprehensive information on the practical application of fire is still restricted, and management information is scattered. Similarly, an improved understanding of how fire affects African mammals is important for the management of both fire regimes and mammal populations. This is also the case in Majete Wildlife Reserve (MWR), Malawi, where a lack of understanding of the past occurrence, determinants, features and effects of prevailing fire regimes prevents the development of appropriate fire management policies. Two separate reviews were conducted to describe the approaches to, and goals of, fire management in African savanna protected areas, as well as the response of large (>5 kg) mammals to fire. For MWR, combinations of remote-sensing and on-the-ground surveys were used to develop a spatially-explicit dataset of the recent fire regime (2001-2019), and to classify, describe and map the woody plant communities present. Additionally, the effect of long-term fire frequencies on vegetation composition, woody plant structure, and large mammal assemblages were assessed, as well as the immediate post-fire habitat selection of large herbivores in a comparative burnt and unburnt landscape. For protected areas, fifteen distinct fire management practices, used to achieve 10 broad ecological (e.g. reversing woody encroachment) and non- ecological (e.g. protecting infrastructure) goals, were identified. Additionally, the responses of 51 mammal species to fire were identified, showing that body size was strongly correlated with fire response, with smaller grazers more likely to respond positively to fire than larger browsers. In MWR, it was found that frequent fires dominate the landscape, with ~57% of MWR burning at intervals of two years or less, and an additional ~30% burning at intervals of 3-5 years. A current mismatch between intended fire management goals and actual trends was also highlighted. Five distinct woody plant communities, two of which were subdivided into three sub-communities each, were recognised, along with 118 woody species identified. Fire frequency had little effect on woody plant community composition, but did affect grass species composition. Mammal species clearly selected for either frequently-burnt or infrequently-burnt areas. Clear selection for either burnt (e.g. impala and warthog) or unburnt (e.g. elephant and bushbuck) habitats, that were unrelated to the availability of above-ground herbaceous biomass, were also shown post-fire. This information is intended to provide a basis for improved fire management planning and policy development, as well as providing a baseline against which to monitor change. Managers should re-evaluate fire policies based on these findings, setting clearly defined targets for the different vegetation types, and introducing flexibility in fire regimes to accommodate natural variation. Establishing a mosaic of patches exposed to different fire frequencies, intensities, seasons and sizes will likely be needed to create a range of habitat types that would best allow for the persistence of all facets of biodiversity in MWR.
... For example, places with the exact same history of composition and configuration of biotic and abiotic components will likely evolve very differently if surrounded by mature forest versus urban development versus agriculture. This kind of neighborhood influence has been expressed as the manifestation of flows of material and energy (as in landscape ecology: [4]), the dispersal of propagules and competitive effects of neighbors (as in plant ecology: [59,60]), spatial autocorrelation (as in geography: [61,62]; as in ecology: [63]), and scale-dependent interconnectedness [37,64] and has been monitored both remotely [65] and with vegetation inventory data [66]. In land cover studies, remotely sensed imagery allows for wall-to-wall classification and mapping of broad areas [67]. ...
Landscape changes and the processes driving them have been a critical component in both research and management efforts of savanna systems. These dynamics impact human populations, wildlife, carbon storage, and general spatio-temporal dynamism in response to both anthropomorphic and climatic shifts. Both biophysical and human agents of change can be identified by isolating their respective spatial, temporal, and organizational contingencies. However, we argue here that a significant portion of savanna research has either considered humans as exogenous (e.g., via enacting regional or broader policies) or somewhat spatio-temporally removed from the system (e.g., as in many protected areas with limited current human habitation). Examples from African savanna research and particularly those systems of southern Africa are thus reviewed and used to model a stylized or prototypical savanna system and contingencies. Such an approach allows for a richer socio-temporal integration of theories and data on past biophysical and human histories to facilitate an improved framework for understanding savanna systems and their complex contingencies as socio-ecological landscapes.
... Fire is the important disturbance that has been described to limit the recruitment of seedlings into taller, mature trees (Higgins et al., 2000). Fire has also had an important effect in controlling the expansion and formation of evergreen macrophyllous thickets (also known as gallery forests (Gignoux et al., 2009)) into savannas (Skowno et al., 1999;Hoffmann et al., 2003;Nangendo et al., 2006;Gignoux et al., 2009). Macrophyllous thicket species are typically slower growing and have thinner bark than faster growing savanna species with thick bark that protects trees from damage to xylem and/or phloem (Gignoux et al., 2009;Midgley et al., 2010). ...
The ingression of woody plants into the grassy layer of savannas and grasslands has become a global concern. The increase of woody plants has been primarily attributed over grazing, fire and more recently to the increase of atmospheric CO2. We used long-term observations and analyses to assess changes in woody vegetation in Ithala Game Reserve (IGR), South Africa. Textural analysis of aerial photographs was used to detect changes in woody vegetation, from 1943 to 2007 in Ithala Game Reserve (IGR), South Africa. Daily rainfall data from 1905 to 2009 were used in a time-series analysis to determine if rainfall patterns have changed. The time-series analysis showed that the low magnitude (0–10 mm) rainfall events decreased from 1916 to 2009 and high magnitude rainfall events increased (10–20 and >20 mm). The mean annual rainfall increased from ∼700 to ∼850 mm from the 1930s to the 2000s. This change in rainfall was a key factor in the increase in woody vegetation from 1943 to 2009. We also used field data from the same reserve collected over 30 years to assess the increases in tree cover. Tree cover and density increased significantly by 32.5% and 657.9 indiv ha−1 respectively, over 64 years. Before the proclamation of IGR in 1972, increases in woody vegetation from 1943 were non-significant. After the proclamation of IGR, herbivore population numbers and spatial distribution influenced the accumulation of grassy biomass required to fuel fires. In areas with reduced fuel loads, the consequential suppression of fire accelerated the rate of woody plant invasion into savannas. The increase in woody vegetation coincided with a decrease in palatable (e.g. Acacia gerrardii and Acacia davyi) and an increase in unpalatable woody plants. The avoidance of the unpalatable trees (e.g. Euclea and Searsia species) by large mammalian herbivores has allowed these trees to increase in density relatively unhindered.
... Generally, C. collinum, C. fascicularis, C. molle, C. capituliflorum, C. ghasalense, G. mollis and A. hockii were the most abundant and frequent species across all land uses. This agrees with Nangendo et al. (2006) that C. molle, G. mollis, A. senegalensis and Grewia bicolor are commonly found in burned areas and in open savanna woodlands in Uganda. Fires are common in these multiple-use savannas, and fire is used as a management tool in both subsistence crop cultivation and livestock grazing. ...
... The overall sampled woody species richness of Nakasongola (99 species, 31 families within 75 plots with an area of 0.1 ha) is lower than the forestwoodland-savanna mosaic of northern Budongo Forest Reserve, north-west Uganda (121 species, 38 families within 594 plots with an area of 0.05 ha; Nangendo et al. 2006). Although both occur within the same ecological zone, the latter is a reserve, where human disturbances are restricted. ...
The density and diversity of woody plant species were studied within grazing, cultivation and charcoal production land-use areas in a multiple-use savanna woodland, central Uganda, using 75 plots with an area of 0.1 ha (Whittaker plots). Plant density was significantly higher under charcoal production (7131 ± 755 plants/ha) and cultivation (6612 ± 665 plants/ha) compared with the grazing lands (4152 ± 525 plants/ha). At the plot level, species richness and Fisher's alpha diversity (α) were relatively low, ranging 2–31 species and 0.34–6.34, respectively, but both were significantly higher under charcoal production and cultivation compared with grazing. Similarly, cumulative species richness and Fisher's alpha diversity were higher under charcoal production and cultivation compared with grazing. Community species composition differed significantly (Global RANOSIM = 0.14, p = 0.001; ANOSIM, ANalysis Of SIMilarity) among land uses. However, the distance of sampling plots away from households, the assumed source of human disturbance to woodlands, accounts for a very small fraction (
... Tropical savannas occur under climatic conditions where there are strongly seasonal rainfall patterns (Frost 1996). They are structured by a continuous grass layer in which trees and shrubs are sometimes scattered ( Nangendo et al. 2006). Meanwhile savanna landscape may be interspersed with riparian or gallery forests, or patches of woodland, swamps or marshes (e.g. ...
What underlies species distribution and species coexistence has long been of key
interest in community ecology. Several methods and theories have been used to
address this question. However, it still remains a controversial debate. The recent
development of plant DNA barcodes with possibility of merging phylogeny with
ecology brings high expectation in uncovering the processes underlying community
assemblages. Previous studies that used molecular approaches in community
ecology focused mainly on rainforests. Using a phylogenetic approach, the current
study contribute to a novel understanding about savanna ecology, especially
regarding how megaherbivores impact plant community composition.
The Kruger National Park (KNP) is one of the world’s largest reserves, but less
studied from a phylogenetic perspective. A DNA database of 445 DNA sequences
(plant DNA barcodes, rbcLa + matK) was generated for the woody plants of the KNP.
This database proves reliable in reconstructing the phylogeny of Angiosperms of the
park. Based on this phylogeny, the present study characterised plant community
composition, and investigated how megaherbivores influence this composition.
Results indicate that plant communities in the KNP are not neutral, i.e. they are more
clustered than expected under various null models. This suggests that ecological
forces, most likely habitat filtering may be playing a key role in dictating community
structure in the KNP. The KNP is well-known for its richness in megaherbivores. The
contribution of these animals to the current shape of plant community structures was
therefore further investigated. Where megaherbivores have been excluded, plant
diversity decreases, but shifts in plant community structure are contingent upon the
initial community composition, suggesting that herbivory might be important filter that
drives the clustering pattern observed.
Abstract
vi
These results also have important implications for management of African
woodlands, particularly given the continental decline in megaherbivores. As large
herbivores are lost from these ecosystems, one can predict a subsequent reduction
in plant diversity, whilst the impact on plant community structure will depend upon
the initial composition. Critically, I also show that the loss of phylogenetic diversity (a
surrogate for functional diversity) will depend on the relative shifts in phylogenetic
community structure, information that has never been considered before in
management strategy.
... The camera trap was located in an old growth forest patch, based on the large number of Uvariopsis congensis (Robyns & Ghesquiere) trees counted in a nearby 10 · 200 m vegetation transect (Aronsen & Teelen, unpublished data). This tree species is considered an old growth specialist (Nangendo, Steege & Bongers, 2006). ...
... It is well known that fire is the single most important factor limiting the re-colonization of grasslands (Lwanga, 2003;Nangendo et al., 2006). In the Budongo Forest Reserve, located north of the Kibale National Park, fire suppression has facilitated the invasion of fire-intolerant species, and this re-colonization is taking place without any re-planting. ...
... While visiting Kibale in 2006, little difference was observed between the replanted and naturally regrowing areas, suggesting that fire suppression alone was the most important factor for recolonization. In the continued absence of fire, forest cover will re-establish itself as forest tree species gain a foothold in grasslands, canopy closure increases, and groundcover vegetation and litter become too moist to propagate fire (Nangendo et al., 2006). In addition, fires can maintain medium levels of disturbance to ecosystems (i.e., the intermediate disturbance hypothesis), creating a more complex ecotone between grasslands and forest ecosystems that produces a more compositionally and structurally diverse landscape, which is likely to support higher biodiversity (Grime, 1973;Connell, 1978). ...
Introduction. Remote sensing technologies can provide detailed assessments of the state of Protected Areas, including critical information on threats (such as deforestation and wildfire), while also facilitating habitat evaluation and change detection. A multitude of satellite-based sensors of varying characteristics are now in operation, enabling the mapping of land cover and land use at various spatial and temporal scales. A new generation of high-resolution satellites, coupled with recent advances in desktop computing power and Geographic Information Systems, has greatly enhanced the ability of conservationists and park managers to integrate remote sensing information into their management plans. For example, many species are restricted to specific habitats that can now be identified with remote sensing (Turner et al., 2003; Goetz et al., 2007; Stickler and Southworth, in press). However, despite the advancements mentioned, the perceived complexities of remote sensing data often discourage non-specialists from leveraging this valuable resource. Here we describe how imagery acquired from the well-known Landsat class of satellites can be used to monitor long-term changes in fire regime and wildlife habitat in Kibale National Park, Uganda, thus contributing to the rich body of long-term research at Kibale focusing on conservation applications. STUDY AREA. The Kibale National Park. Located in southwestern Uganda, the 793 km2 Kibale National Park is one of only a few blocks of tropical forest remaining in the country. Only 3% of Uganda remains covered by rainforest, with nearly all found in the southwestern portion of the Albertine rift.
... These numbers are slightly lower than our analysis of the circular plots where we observed an average of 668 trees 2-20 cm dbh/ ha, with and additional 100.7 trees >20 cm dbh/ha. In either case, this stand density is low compared to many dry tropical forest sites (Gentry, 1995;McLaren et al., 2005) but fits well within African savanna or open woodland classifications (White and Hood, 2004;Aerts et al., 2006;Nangendo et al., 2006). Examining patterns in the nearest neighbor analyses we found that adult trees are less spatially clumped than smaller trees (Fig. 4). ...
... As a consequence, nearly 100% of the landscape, both inside and outside of protected areas is burned each year. This is a very high fire frequency for a dry tropical forest ecosystem and several recent studies have shown that the forest-woodland-grassland complex of much of central Africa is dependent on fire frequency and intensity (Nangendo et al., 2006). Our findings show evidence of such frequent burning with a tree size class structure indicative of continued recruitment within this system (i.e., far more small individuals than larger ones). ...
We describe tree diversity, forest community composition and vegetation structure in dry forest miombo woodland in the Katavi-Rukwa ecosystem of western Tanzania. Tree diversity was high (45 families, 117 genera, 229 species) and concentrated in the Fabaceae (30 genera, 73 species). A strong majority (75%) of 19,481 sampled trees were aggregated in just 12 genera spread among 11 families, with individuals in the genera Grewia (17.42%), Markhamia (13.20%) and Combretum (13.13%) dominating abundance. Assessing dominance in terms of a combined importance value (IV300, summed relative abundance, basal area and frequency), showed Terminalia sericea, Combretum adenogonium, and C. colinum as the dominant tree species. Thus, woodlands in this region are atypical of the miombo biome in which it is embedded with only six of fifty 0.1ha quantitative plots dominated by species in one of the classic miombo genera (Brachystegia, Julbernardia, or Isoberlinia). Ordination of data from these 50 plots revealed a diffuse structure of communities. Moreover, trees were found to be spatially clumped within, as well as among, plots. By documenting how the Katavi-Rukwa ecosystem is comprised of a patchwork of locally dominant common trees intermixed with a diverse assemblage of less common species, which have few specific associations with particular dominants, our study begins to fill an important gap in understanding composition and structure of dry forests that still occupy so much of southern-central Africa.
