Baobabs and elephants

Guy, Pierre

doi:10.1111/j.1365-2028.1982.tb00295.x

Cited by 17 publications

(8 citation statements)

References 3 publications

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“…To sample all available age classes turned out to be problematic, since baobabs of several age classes show different growth rates (swart 1963;GUy 1970;GUy 1982;BreitenBaCh 1985) and react quite individually to poor, inconsistent or heavy rainfall. Two neighbouring baobab trees growing under the same site conditions were found to show strongly different growth trends over the last 19 years; most likely due to age differences expressed by circumference (Bao20: 2.5 m, Bao21: 5.5 m).…”

Section: Discussionmentioning

confidence: 99%

Baobabs on Kubu Island, Botswana – A dendrochronological multi-parameter study using ring width and stable isotopes (δ13C, δ18O)

Slotta¹,

Helle²,

Heußner³

et al. 2017

Erdkunde

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Summary: According to the Intergovernmental Panel on Climate Change (IPCC), all of Africa is very likely to warm up more than the global average during this century. Especially (semi-)arid regions are expected to experience particularly high warming and possibly catastrophic droughts. However, assessments of the impacts of climate change on these regions are currently impeded by a lack of transregional high temporal resolution proxy data for the African continent. Baobab trees are widely distributed in (semi-)arid Africa and can reach ages of up to 2000 years. This pilot study was aimed at investigating African baobabs, Adansonia spp., from a site in Botswana using multiple dendroclimatological methods. Increment cores from 16 individual baobabs growing on Kubu Island (20°53' S, 25°49' E), a granite pluton located in the Kalahari, were collected in June 2011 to test for annual growth and the species' utility for palaeoclimatic studies. Due to the particular wood fabric and relatively high water content, baobab increment cores were packed in air-tight opaque tubes and stored in a freezer to prevent drying and mould formation. The complicated wood anatomical structure was found to be analysed best using a microscope with incident UV light, allowing tree-ring boundaries to be distinguished. Nonetheless, potential differences in individual site conditions, as well as diverse tree ages, caused conventional dendrochronological crossdating to fail. Missing and false tree rings could be identified due to the strong relationship between tree-ring width and annual precipitation amount allowing the development of a preliminary 50 year-long baobab chronology . Subsequently, stable carbon and oxygen isotope analyses revealed significant correlations of Δ 13 C and δ 18O of tree rings with climate data. Year-to-year isotope variability and trends were found to be in good agreement with established models of fractionation. Intrinsic water-use efficiency has mainly increased over the study period (2-30 %). Despite the demonstrated high potential of African baobabs as a valuable high-resolution climate archive, we conclude that more dendrochronological calibration studies are required at various sites in southern Africa. Furthermore, ecophysiological monitoring of climate and stable isotope signal transfer from the atmosphere, through soil and leaves into the tree rings is necessary to fully understand tree-ring formation and climate response of the African baobab.Zusammenfassung: Laut Weltklimarat (Intergovernmental Panel on Climate Change, IPCC) wird Afrika sehr wahrscheinlich eine Erwärmung erfahren, die über dem globalen Mittel liegen wird. Speziell aride Gebiete sind durch eine hohe Erwärmung und mögliche katastrophale Dürren gefährdet. Den Einschätzungen der Auswirkungen des Klimawandels auf diese Regionen steht aber derzeit ein großer Mangel an überregionalen, zeitlich hochaufgelösten und präzise datierten Proxy-Datenreihen für den afrikanischen Kontinent entgegen. Baobabs sind im (semi-)ariden Afrika weit verbreitet und k...

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Section: Discussionmentioning

confidence: 99%

Baobabs on Kubu Island, Botswana – A dendrochronological multi-parameter study using ring width and stable isotopes (δ13C, δ18O)

Slotta¹,

Helle²,

Heußner³

et al. 2017

Erdkunde

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“…In at least some dry forests, increasing numbers of elephants progressively destroy the forest and convert it into more open habitats (Laws, 1970;Barnes, 1980Barnes, , 1983Douglas-Hamilton, 1987;Dublin, Sinclair & McClade, 1990;Jachman & Croes, 1991;Dublin, 1994;Leuthold, 1996;see Lawton & Gough (1970), Guy (1982) and Ben-Shahar (1996) for alternative explanations). In KNP, elephants also suppress the rejuvenation of selected woodland trees (Viljoen, 1988;Trollope et al, in press).…”

Section: Why Control Elephant Numbers?mentioning

confidence: 99%

Managing the elephants of Kruger National Park

Whyte

Aarde

Pimm

1998

Animal Conservation

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The elephant population in Kruger National Park, Republic of South Africa, is growing rapidly. To prevent damage to the Park's ecosystems, the management has culled about 7% of the population annually. Such culls are very controversial. At first glance, contraceptives seem an attractive alternative means of control. We examine contraception as a management option, review the relevant aspects of elephant reproduction, physiology and demography and conclude that this optimism is probably misplaced. First, contraceptives have a wide range of physiological and behavioural side-effects that may prove to be damaging to the individual female and those around her. Second, the elephants in the Park have near-maximal growth rates with inter-calving intervals of less than four years. To achieve zero population growth, about three-quarters of the adult female elephants would need to be on contraceptives. There are no simple alternatives. The smallest numerical target for controlling population numbers is to kill or sterilize females about to become pregnant for the first time. Such a solution is unlikely to appease those who consider killing elephants to be unethical. It may, however, be the one closest to the natural patterns of elephant mortality.

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“…Taken with the results of other aerial elephant surveys conducted post 1992 drought, elephants in Gonarezhou have increased at a mean annual rate of 6% during the past sixteen years. Such a high elephant population annual rate with a population density of 2 elephants km -2 is a cause for concern to a park the size of Gonarezhou (Dunham 2012), especially considering the role of elephants in structuring ecosystems (Guy 1982;Cumming et al 1997;Midgley et al 2005;Guldemond and Van Aarde 2008).…”

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confidence: 99%

Status of African baobab (<i>Adansonia digitata</i>) across Gonarezhou National Park, Zimbabwe

Mashapa¹,

Nyabawa²,

Zisadza-Gandiwa³

et al. 2014

Journal of Applied Sciences and Environmental Management

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An assessment was done to determine the abundance and structure of baobab (Adansonia digitata) across Gonarezhou National Park, Zimbabwe. Baobabs were sampled on fifteen belt transects of constant width of 300 m with fifteen baobabs in each belt transect determined the length of a particular belt transect between May and June 2012. Our results showed that there were no significant differences in basal area, height and density of baobabs across Gonarezhou. Moreover, elephant (Loxodonta africana) dung counts and damaged baobabs were similar across Gonarezhou. Our findings suggest a relatively similar spatial effect of elephant herbivory and other disturbance regimes on baobabs in Gonarezhou. We recommend the continuous monitoring of baobab woodland stands across Gonarezhou. © JASEM

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Baobabs and elephants

Cited by 17 publications

References 3 publications

Baobabs on Kubu Island, Botswana – A dendrochronological multi-parameter study using ring width and stable isotopes (δ13C, δ18O)

Baobabs on Kubu Island, Botswana – A dendrochronological multi-parameter study using ring width and stable isotopes (δ13C, δ18O)

Managing the elephants of Kruger National Park

Status of African baobab (<i>Adansonia digitata</i>) across Gonarezhou National Park, Zimbabwe

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