Elephant Density Research Articles

Population density of elephants and other key large herbivores in the Amboseli ecosystem of Kenya in relation to droughts

Kenya/Tanzania borderland is a critical area for conservation of biodiversity. This study was done to establish the effects of 2007 and 2009 droughts through aerial counts. Findings indicate that large mammal population collapsed, but some species crashed more than others. Total large mammal density declined over three times (−207.43%), recovering modestly (+41.59%) between 2010 and 2013. Over that time, the most abundant species was zebra (10,466.3 ± 2860.5 animals), followed by wildebeest (8921.0 ± 4897.9), Grant's gazelle (3447.0 ± 303.7), Maasai giraffe (1381.3 ± 132.7), African elephant (990.67 ± 12.60), eland (544.0 ± 311.4), Thomson's gazelle (495.3 ± 232.3), buffalo (331.3 ± 128.8) and impala (354.3 ± 61.0). The species affected most by drought was lesser kudu, followed by African buffalo, Maasai giraffe, kongoni, common eland, common wildebeest, common zebra, Grant's gazelle, gerenuk, impala, African elephant, Thomson's gazelle and fringe - eared Oryx respectively. Further, large mammal species numbers were dependent on location (χ2 = 13,647.35, df = 15, p < 0.001), with numbers being higher near protected areas. Animals with low numbers, specific diets, water - dependent and limited range were most affected by the drought. This provides a baseline for future comparisons and also future effects of droughts.

Change in woody cover at representative sites in the Kruger National Park, South Africa, based on historical imagery.

BackgroundThe coexistence of woody vegetation and grass is a key characteristic of savanna ecological balance. Gains in woody vegetation at the expense of grass can lead to changes in grazer and browser carrying capacities on the savannas. This study examined long-term change in woody cover at four study sites representative of the geology and rainfall in the Kruger National Park, South Africa. Scanned 1940/1942, 1968, and 1977 high spatial resolution (0.44–1.35 m) panchromatic aerial photographs were used, supplemented by 5 and 10 m resolution 1998 and 2012 panchromatic and red band grey scale digital SPOT images. The imagery datasets of the respective study sites were georeferenced to the UTM projection. Woody cover on the imagery was enhanced using texture analysis, and mapped by unsupervised classification of the texture images using the K-means clustering algorithm. Change in woody cover was mapped using Boolean addition Geographic Information System overlay analysis.ResultsThe results indicated 29 and 40 % reductions in woody cover for the southern granites and southern basalts sites, respectively. The northern granites and northern basalts sites, on the other hand, had gains in woody cover over the analysis period. The location context-specific factors of fire frequency and elephant density, and not rainfall fluctuations, explained most of the change in woody cover.ConclusionsThe results point to the need for location context-specific management of fire and elephant concentrations. The changes in woody cover are likely to have effects on the grazer and browser carrying capacities of the savannas in the Kruger National Park.

Different drivers create spatial vegetation cover and vertical structure in semi-arid African savannas

Important drivers of woody cover in African savannas are rainfall, soil and nutrients, and disturbance factors, such as fire and herbivory. However, very little is known about how these drivers influence woody cover at specific height classes. The main aim of this study was to identify which of these drivers are the best predictors of woody cover at three height classes: shrub (0.75–2.5 m), brush (2.5–5.5 m) and tree (>5.5 m). Percent woody cover estimates were collected using a rapid monitoring technique over 1 700 sites in Kruger National Park, South Africa. Geology (basalt and granite), mean annual rainfall, fire frequency and elephant density were analysed as potential drivers of woody cover. Results indicate that mean annual rainfall was negatively associated with shrub cover, fire frequency was negatively associated with brush cover, and elephant density was negatively associated with tree cover. Patterns of woody cover show that while geology influences the spatial distribution of horizontal woody cover, variation in vertical vegetation structure is created and maintained by top-down disturbance. This provides the first documentation of drivers associated with structurally differentiated woody cover at regional scales. Future studies on woody cover in disturbance-driven environments should not ignore vegetation structure.

Precipitation and elephants, not fire, shape tree community composition in Serengeti National Park, Tanzania

AbstractSavannas are spatially diverse, variable and are susceptible to high rates of disturbance from fire and herbivory. There is significant interest in woody cover dynamics in relation to disturbance regimes. Less effort has been devoted to understand processes that drive tree community composition. In this study, tree species composition data collected at the landscape scale in the Serengeti were used to identify key environmental factors driving variation in species composition. A system of 38 plots clustered within 10 sites spanning the mean annual precipitation (MAP) gradient was used to assess the relative role of bottom‐up (precipitation, soil nutrients and soil texture) vs. top‐down factors (fire and elephant herbivory) on tree community composition. We developed candidate models relating tree species composition (based on multivariate community analysis) to different combinations of plot‐level environmental covariates. Results suggest that tree community composition is largely driven by MAP and is associated with elephant population density. Strikingly, we found no evidence that fire influences species compositional turnover. In a second analysis, we used structural equation model (SEM) to explore the possible direction of association between elephant density and tree species composition. We compared a model that included elephant effects on composition to one that included community composition effects on elephant density. Results suggest that variation in elephant population density across space is more likely to drive tree community composition and not vice versa. We propose that precipitation and herbivory, rather than fire, determine tree species composition in Serengeti Acacia tree community.

Elephant damage, not fire or rainfall, explains mortality of overstorey trees in Serengeti

Summary Generalizations about the drivers of tree demography in tropical savannas continue to prove difficult because of the complex and dynamic interactions involved, and because multi‐year data sets spanning meaningful gradients in potential drivers are lacking. Overstorey trees play disproportionate roles in the long‐term dynamics and functioning of savanna ecosystems. Understanding demographic patterns in these trees is complicated by their resprouting ability after being top‐killed and few studies have attempted to separate top‐kill from true mortality events. We examined the interactive effects of fire frequency, mean annual precipitation and elephant herbivory on overstorey (&gt;2 m) tree mortality between 2009 and 2014 across 32 permanent vegetation plots in the Serengeti Ecosystem, Tanzania. Mean tree mortality over the study period was 0.28 ± 0.02 (0.07 year−1). Among trees that were top‐killed (19.1% of all individuals), 31.2% resprouted. Mortality was driven largely by elephant herbivory, though mortality rates varied considerably across space and tree species. Fire frequency and mean annual rainfall were weak predictors of tree mortality. Over the 5 year period, chronic elephant herbivory (i.e. repeated through time) was a stronger predictor of tree mortality than maximum elephant herbivory, suggesting that repeated, low‐intensity damage from elephants was more important to mortality than acute, but infrequent, damage. Elephants disproportionately damaged certain tree species relative to their availability on the landscape, and the tolerance to damage differed by species as well. Acacia senegal was strongly selected and appeared to have low tolerance to damage when it occurred, resulting in a mortality rate of 0.736 ± 0.052 (0.234 year−1) over the study period. Top‐killing and resprouting rates varied across species, with Acacias generally having low resprout rates. Synthesis. Our study highlights the considerable role that chronic herbivory plays in structuring savanna tree populations, irrespective of prevailing fire and rainfall conditions, and provides important vegetative context to the dramatic recent declines and (in the case of Serengeti) increases in savanna elephant densities in sub‐Saharan Africa.

Decline and Die-Back of Woody Plants in a Physiognomic and Floristically Complex Sebungwe Region and the Factors Modifying Mosaic Patch Landscapes at Sengwa Wildlife Area, Zimbabwe

An investigation of the status of woodlands at Sengwa Wildlife Research Area (SWRA) revealed factors influencing decline and die-back of woody plants at a time of low elephant densities. The vegetation condition of the study area in the elephant range area of the semi-arid area of northwest Zimbabwe was randomly assessed in 50 × 20 m permanently marked degraded and undegraded plots in a study area approximately 80 km2. Diversity of woody plants increased towards downstream. Percentage elephant damage was slight on undegraded plots and termite damage was three times greater on undegraded plots than degraded plots. Density of woody plants was high following a period of coppice regeneration. The results suggest regeneration of woody plants following a long period of elephant culls between 1960 and 1992 that altered forest structures. It is conceivable that other environmental agents may play the role of elephant damage in the presence of elephant densities < 1 individuals/ km2. Significant differences (p<0.05) in elephant densities (no/km2) were recorded in SWRA between 1958 and 1996, 1958 and 1993 suggesting that increasing elephant densities were negatively impacting on woody cover (%). Woody cover increased from 60% in 1993 to 70% in 1996 inside SWRA. SWRA vegetation may be on regeneration path if no adverse impacts are recorded from other environmental agents including termite activity, fungal attack (Fusarium oxysporum), Lantana camara L. invasions and drought. Epidemic die-back is not yet a common feature in the protected area. The results refute the postulation that elephant alone prevent woodland regeneration and recruitment into larger size classes by feeding on small trees. The findings suggest need to consider end to end cycle of each disturbance factor in order to accurately predict scale of vegetation change in savanna ecosystems.

Megafaunal influences on tree recruitment in African equatorial forests

The forests of central Africa are distinct from counterpart forests in Amazonia by having fewer trees ≥ 10 cm dbh ha−1, especially small trees &lt; 20 cm dbh, and in having sapling cohorts with less diversity than canopy trees. We tested four hypotheses to investigate whether herbivory, in particular, browsing by forest elephants, could be a factor in these differences. We found that the density of small saplings and diversity of large saplings were inversely associated with local density of elephants. We then tested the hypothesis that steep slopes might serve as refugia from elephant foraging, but found that elephants routinely forage on slopes with an inclination of less than ca 30 deg. Nevertheless, the diversity of small trees (≥ 10 cm, &lt; 20 cm dbh) was higher on slopes than on paired level‐ground sites. The incidence of break scars on saplings ≥ 2 cm dbh and &lt; 6 cm dbh was greater (107/100 stems) on level ground than on slopes (77/100 stems), although high variability precluded statistical significance. After correcting for background breakage not caused by elephants, an estimated 71% of breaks on level ground and 43% of breaks on slopes were attributable to elephants. Liana loads borne by trees at different sites were highly variable and unrelated to slope. Apparently, disturbances are more critical to liana development than herbivory. Elephants, along with other large mammals such as gorillas, duikers, red river hogs and rodents, appear to act as powerful filters on the tree recruitment process in African forests that still retain intact megafaunal communities.

Ecosystem‐scale effects of megafauna in African savannas

Natural protected areas are critically important in the effort to prevent large‐scale megafaunal extinctions caused by hunting and habitat degradation. Yet such protection can lead to rapid increases in megafauna populations. Understanding ecosystem‐scale responses of vegetation to changing megafaunal populations, such as the case of the African elephant Loxodonta africana in savannas, requires large‐scale, high‐resolution monitoring over time. From 2008 to 2014, we repeatedly surveyed the fate of more than 10.4 million woody plant canopies throughout the Kruger National Park, South Africa using airborne Light Detection and Ranging (LiDAR), to determine the relative importance of multiple environmental, biotic and management factors affecting treefall rates and patterns. We report a mean biennial treefall rate of 8 trees or 12% ha−1, but with heterogeneous patterns of loss in both space and time. Throughout Kruger, the influence of elephant density on treefall was matched only by spatial variation in soils and elevation, and all three factors co‐dominated park‐wide treefall patterns. Elephant density was up to two times more influential than fire frequency in determining treefall rates, and this pattern was most pronounced for taller trees (&gt; 2 m in height). Our results suggest that confining megafauna populations to protected areas, or reintroducing them into former or new habitat, can greatly alter the structure and functioning of the host ecosystem. Conservation strategies will need to accommodate and manage these massive ecological changes in the effort to save megafauna from extinction, without compromising system functionality.

Non-Invasive Genotyping of Sumatran Elephants: Implications for Conservation

Reliable baseline information necessary for the monitoring and conservation of Sumatran elephants is scarce. We here combine non-invasive molecular genetics methods and capture-recapture modeling to estimate elephant population size, distribution, sex ratio, and age structure for the Bukit Tigapuluh landscape in Sumatra, Indonesia. Two separate subpopulations were found, for which we estimated a population size of 99 (95% CI = [86,125], PCCL = 38.59%) and 44 elephants (95% CI = [ 37 , 56 ], PCCL = 43.18%), respectively. Low elephant densities are likely the result of patchy habitat usage and anthropogenically increased mortality, the latter assumption being supported by strong skews in both sex ratio and age structure as well as direct evidence of elephant killing. Still, the Bukit Tigapuluh landscape currently holds the largest known population of elephants in central Sumatra, representing one of the most important areas for their conservation in Indonesia. Conservation of both the elephant population and their habitat in this region should thus be of high priority. We identified several threats to the population, including (i) the risk of inbreeding and subsequent loss of genetic diversity, (ii) illegal elephant killing, and (iii) the lack of protected habitat. In order to overcome these challenges we suggest: (i) the implementation of a meta-population management program, (ii) monitoring and safeguarding elephants and improving law enforcement, and (iii) providing sufficient safe habitat to mitigate human-elephant-conflict (HEC) and ensure elephant survival.

Reliable monitoring of elephant populations in the forests of India: Analytical and practical considerations

Reliable estimation of elephant population abundance and density assumes great importance in the context of massive threats from illegal hunting and habitat loss. However, available estimates of elephant populations, particularly in Asia, are often unreliable and misleading. We evaluate sources of bias and imprecision in commonly used estimation approaches, and demonstrate that if correctly applied, line transect sampling based on visual detections of elephant clusters can address these issues. We compare our own early transect surveys on foot that relied on purposive line placement, to subsequent surveys in 2011, which employed rigorous survey designs. Estimated elephant density (D^(95%CI^(D^)) in our study sites in India, ranged between 0.25(0.12–0.53) and 3.29(1.74–6.21) elephants/km2 in the earlier surveys and between 0.32(0.14–0.75) and 2.24(1.41–3.56) elephants/km2 in the 2011 survey. Although coefficients of variation of estimated detection probability (pˆ) and cluster size (E^(S)) were higher at low sample sizes, they dropped to<15% with n>40 detections. Variance of encounter rate (n/l) was the largest contributor to the variance of density estimates. We recommend that rigorous line transect surveys must ensure: random transect placement with systematic and sufficient spatial replication to ensure adequate spatial coverage; coverage of sufficiently large areas in a short duration to ensure population closure; and investment of adequate effort to ensure reasonable number of detections. Field and analytical protocols presented here can enable reliable estimation of density and abundance of other wildlife species that can be visually detected in forests. They can lead to improved animal monitoring programs that are central to rigorously evaluating the effectiveness of widely employed, expensive conservation interventions meant to counter massive anthropogenic threats facing elephants and other large, diurnal species.

Elephant-mediated habitat modifications and changes in herbivore species assemblages in Sabi Sand, South Africa

Elephant Loxodonta africana conservation might indirectly influence the wider herbivore community structure, as elephants have the ability to significantly modify the savanna habitat. Uncertainty remains as to the consequences of these effects, as elephants might either compete with other species or facilitate foraging especially for grazers and smaller browsing species by increasing the amount of grass or the amount of browse at lower feeding heights. We studied these potential cascading effects of elephants by using 16 years of data (1992–2011) from the Sabi Sand Wildtuin, South Africa, which showed a steady increase in elephant densities from 0.12 to 2.03 elephants/km2 over this period. We demonstrate that tree densities, and browse availability at feeding heights below 2 m, decreased with increasing elephant densities, and that there was no positive effect of elephants on browse availability. The changes in elephant densities were good predictors (R 2 adj > 0.50) in explaining population fluctuations of other herbivore species. The total body mass of grazers increased more than that of the browsers, shifting the community toward a grazer and megaherbivore-dominated community. An increasing density of elephants changes the composition of the herbivore community, as mesobrowsers are unable to benefit from the impact of elephants on trees, but megagrazers show strong positive responses. Hence, changes in elephant densities as a result of poaching or conservation may trigger cascading community effects. These are neglected but important consequences of (negative or positive) human impacts on elephant numbers, especially in restricted areas such as reserves and national parks.

Modeling elephant-mediated cascading effects of water point closure.

Wildlife management to reduce the impact of wildlife on their habitat can be done in several ways, among which removing animals (by either culling or translocation) is most often used. There are, however, alternative ways to control wildlife densities, such as opening or closing water points. The effects of these alternatives are poorly studied. In this paper, we focus on manipulating large herbivores through the closure of water points (WPs). Removal of artificial WPs has been suggested in order to change the distribution of African elephants, which occur in high densities in national parks in Southern Africa and are thought to have a destructive effect on the vegetation. Here, we modeled the long-term effects of different scenarios of WP closure on the spatial distribution of elephants, and consequential effects on the vegetation and other herbivores in Kruger National Park, South Africa. Using a dynamic ecosystem model, SAVANNA, scenarios were evaluated that varied in availability of artificial WPs; levels of natural water; and elephant densities. Our modeling results showed that elephants can indirectly negatively affect the distributions of meso-mixed feeders, meso-browsers, and some meso-grazers under wet conditions. The closure of artificial WPs hardly had any effect during these natural wet conditions. Under dry conditions, the spatial distribution of both elephant bulls and cows changed when the availability of artificial water was severely reduced in the model. These changes in spatial distribution triggered changes in the spatial availability of woody biomass over the simulation period of 80 years, and this led to changes in the rest of the herbivore community, resulting in increased densities of all herbivores, except for giraffe and steenbok, in areas close to rivers. The spatial distributions of elephant bulls and cows showed to be less affected by the closure of WPs than most of the other herbivore species. Our study contributes to ecologically informed decisions in wildlife management. The results from this modeling exercise imply that long-term effects of this intervention strategy should always be investigated at an ecosystem scale.

Decline of sable antelope in one of its key conservation areas: the greater Hwange ecosystem, Zimbabwe

AbstractLand use has major effects on wildlife conservation. We studied variations of sable antelope Hippotragus niger densities between 1990 and 2001 in comparison with various land uses in and around Hwange National Park, Zimbabwe. Trends of other ungulates, including elephant Loxodonta africana, were examined simultaneously, because sable may be sensitive to forage and apparent competition and to high elephant densities. Sable densities declined in the whole region, very likely because of adverse rainfall conditions. Densities were constantly higher in the hunting areas and forestry lands than in the national park. Interestingly, elephant densities showed the opposite, with higher densities in the national park than in the adjacent areas. Whether these results reflect a negative effect of high elephant numbers on sable must still be tested directly. Likewise, while habitat characteristics and lion predation did not appear responsible for the higher sable densities outside the national park, they could not be discounted as an influence on the differing sable densities in different land‐use areas. It is clear, however, that high protection status is not always sufficient to ensure adequate conservation of flagship species. We therefore call for further investigations of ecological interactions within protected areas.

Elephant (Loxodonta africana) Disturbance to Riparian Woodland: Effects on Tree-Species Richness, Diversity and Functional Redundancy

The substantial increase in elephant populations across many areas in southern Africa over past decades is prompting concerns about the effects on biodiversity. We investigated the outcomes of elephant disturbance on tree-species presence, density, and richness, and on alpha and beta diversity within riparian woodland in Chobe National Park, Botswana. We enumerated all tree species occurring in 32 plots (0.06 ha) along the Chobe riverfront. Plots were stratified by soil type (nutrient-rich alluvium vs. nutrient-poor Kalahari sand covering alluvium) and elephant impact (high vs. low impact on both soil types). We tested four predictions: elephants reduce tree density, richness, and alpha diversity; beta diversity is greater in vegetation subjected to high elephant impact; elephant impact on tree-species composition is greater on nutrient-poor than on nutrient-rich soil; and the loss or decline of abundant tree species on heavily disturbed sites is offset by an increase in abundance of functionally similar species, ones that are minor on lightly disturbed sites. Elephant browsing substantially affected tree-species composition, reducing density, species richness, evenness, and alpha diversity but had no effect on beta diversity. The dominant species on relatively undisturbed areas were partly replaced by functionally similar species on heavily disturbed sites. Soil type influenced species composition on lightly disturbed sites but was less important at higher elephant densities. Our findings are important for areas with extreme dry-season densities of elephants but should not be extrapolated to infer purported effects of elephants on tree diversity at lower densities.

Does trophy hunting matter to long‐term population trends inAfrican herbivores of different dietary guilds?

AbstractThe persistence of largeAfrican herbivores in trophy hunting areas is still unclear because of a lack of data from long‐term wildlife monitoring outside national parks. We compared population trends over the last 30 years inHwangeNationalPark,Zimbabwe, and the neighbouringMatetsiSafariArea where large herbivores were harvested at an average yearly rate of 2%. We investigated whether trophy hunting altered densities and the proportion of adult males in several large herbivore species. Large herbivores generally thrived as well, or even better, in the hunting areas than in the national park. The proportion of adult males did not differ between the two zones, except for species with higher harvest rates and proportionally more males harvested. Densities were not lower in the hunting areas than in the national park, except for elephant and impala. Large herbivores generally declined throughout the 30‐year period in both zones, particularly selective grazers. This is probably because of their greater sensitivity to variation in rainfall compared with other herbivores. Rainfall indeed declined during the study period with droughts being particularly frequent during the 1990s. Browsers, mixed feeders and non‐selective grazers generally declined less in the hunting areas than in the national park, possibly because of lower densities of natural predators and elephants outside the park. Our study highlighted that large herbivores may persist in trophy hunting areas as well as in national parks. When rigorously managed, trophy hunting areas may be relevant conservation areas for large herbivores, particularly under the current global decline of wildlife abundance acrossAfrica.

Elevated elephant density does not improve ecotourism opportunities: convergence in social and ecological objectives

In order to sustainably conserve biodiversity, many protected areas, particularly private protected areas, must find means of self-financing. Ecotourism is increasingly seen as a mechanism to achieve such financial sustainability. However, there is concern that ecotourism operations are driven to achieve successful game-viewing, influencing the management of charismatic species. An abundance of such species, including the African elephant (Loxodonta africana), has been stocked in protected areas under the assumption that they will increase ecotourism value. At moderate to high densities, the impact of elephants is costly; numerous studies have documented severe changes in biodiversity through the impacts of elephants. Protected areas that focus on maintaining high numbers of elephants may therefore face a conflict between socioeconomic demands and the capacity of ecological systems. We address this conflict by analyzing tourist elephant-sighting records from six private and one statutory protected area, the Addo Elephant National Park (AENP), in the Eastern Cape Province of South Africa, in relation to elephant numbers. We found no relationship between elephant density and elephant-viewing success. Even though elephant density in the AENP increased over time, a hierarchical partitioning analysis indicated that elephant density was not a driver of tourist numbers. In contrast, annual tourist numbers for the AENP were positively correlated with general tourist numbers recorded for South Africa. Our results indicate that the socioeconomic and ecological requirements of protected areas in terms of tourism and elephants, respectively, converge. Thus, high elephant densities and their associated ecological costs are not required to support ecotourism operations for financial sustainability. Understanding the social and ecological feedbacks that dominate the dynamics of protected areas, particularly within private protected areas, can help to elucidate the management challenges of minimizing ecological trade-offs while meeting ecotourist demands and achieving sustainability.

Identifying drivers that influence the spatial distribution of woody vegetation in Kruger National Park, South Africa

Understanding the dynamics of woody tree species distribution in savanna systems remains a challenge despite considerable attention the topic has received in recent years. Disturbances such as fire and elephant effects on woody vegetation are well documented, yet the influence of these factors on emerging landscape‐scale patterns such as height and species distributions continue to be poorly understood. The aim of this study was to identify how a suite of environmental variables (rainfall, temperature, aspect, slope, geology, fire frequency and elephant density) and their relative contributions, may affect woody species distribution in relation to structural height classes. Using the Maximum Entropy model for three structural height classes of the fifteen most frequently occurring woody species in the Kruger National Park (South Africa), the environmental variables best explaining each species distribution were identified. The three structural classes were defined to capture canopy height categories of specific management interest, namely Shrub (0.75–2.5 m), Brush (2.5–5.5 m) and Tree (over 5.5 m). The weighted contributions of environmental variables for each species and its associated size class were further analyzed for similarities using a resemblance matrix based on the Bray‐Curtis similarity index coupled with a hierarchical clustering test. Our main findings suggest that the patterns and processes driving woody composition and structure are largely decoupled and that the distribution of different structural classes of a particular species may not be driven by the same environmental variables. Future studies should take cognizance of this as ignoring one or the other may lead to confounding results.

An elephantine challenge: human–elephant conflict distribution in the largest Asian elephant population, southern India

Wildlife conservation is a complex issue especially when it involves large carnivores or mega-herbivores that are conflict-prone. Karnataka state in southern India is known to harbor high density of wild elephants. This conservation success story also has opportunity costs for communities living in close proximity to elephants. Despite the fact that human–elephant conflict is a serious conservation and social issue, there is little quantitative understanding of conflict especially over large areas. Here we conduct the first analysis of human–elephant conflict distribution, severity and explanatory factors over the entire state of Karnataka. We use data from the state forest department records on villages that experience conflict, compensation payments made by the government, elephant densities, forest cover and perimeter, and presence of physical barriers to mitigate elephant conflict. In total, 60,939 incidences of crop loss were reported and US$ 2.99 m paid in compensation during April 2008–March 2011. A total of 91 people were killed by elephants and 101 elephants died in retaliatory killings during the study period. A total of 9.4 % of the state’s geographic area covering 25 of the 42 forest administrative divisions were affected. There was no significant difference in conflict incidences or compensation given between protected areas and non-protected areas. There was no correlation between conflict incidences/unit area and elephant density, forest cover, forest perimeter of protected areas and presence of physical barriers. The results depict the importance of efficient management of physical barriers, conserving key habitat linkages, and acts as baseline data for future work.

Survey ofLoxodonta africana(Elephantidae)-caused bark injury onAdansonia digitata(Malavaceae) within Pendjari Biosphere Reserve, Benin

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English

Sustainable management of plant-herbivore systems requires an understanding of their long-term dynamics through modeling approaches. A preliminary simulation model was developed using STELLA to predict the impacts of elephants and fire on the structure of semi-arid miombo woodlands of north-western Zimbabwe. Elephants alone at a density of 0.27 km-2 will convert the woodland into coppice in 120 years due to resulting massive declines of large trees. The same result is achieved in only 10 years if elephant density is at 2 km-2. The pattern remains similar with simultaneous application of fire once every 4.7 years with elephants at 0.27 km-2. When elephants are culled at 30% whenever their densities reach 1 km-2, the woodland does not degenerate into coppice despite fire occurrence once every 4.7 years. Therefore, elephants alone can degrade and maintain semi-arid miombo woodland into coppice, largely due to their damaging impacts on mature canopy trees and fire acts to speed up the process by suppression of an already low recruitment. Fire alone has a lesser influence on woodland structure than elephants because of low fuel loads due to heavy grazing and low grass production as a result of low rainfall and inherently poor soils in the area. A maximum elephant density of 0.1 km-2 is recom-mended to achieve equilibrium in the area. Key words: Zimbabwe, Sengwa, STELLA, elephants, fire, miombo woodlands, simulation model.