Continued decline in tree euphorbias (Euphorbia tetragona and E. triangularis) on the Great Fish River Reserve, Eastern Cape, South Africa
Lent, P.C. ; Eshuis, H. ; Krimpen, R. van; Boer, W.F. de - \ 2010
African Journal of Ecology 48 (2010)4. - ISSN 0141-6707 - p. 923 - 929.
A dramatic decline averaging 43% over a 4-year period has occurred in tree Euphorbia (Euphorbia tetragona and Euphorbia triangularis) populations on the Great Fish River Reserve, South Africa. These changes are evident from data gathered by general vegetation monitoring methods as well as from a focused study of four tree Euphorbia populations. The decline from 2003 to 2007 was more marked for E. triangularis than for E. tetragona and was accompanied by a general absence of seedlings and a reduced presence of younger age classes of both species, decreasing the proportion of younger trees in the populations. The role of megaherbivores, specifically the black rhinoceros, in these changes is well established. However, the impact of baboon activity, leading to damage to tree crowns and upper branches, is also substantial, especially on E. triangularis populations. Damaged crowns were recorded significantly more often for E. triangularis than for E. tetragona, and the damage frequency increased with decreasing tree height. Thus, our work provides the first evidence that these two closely related Euphorbia species may be affected differently by herbivory.
Impact of black rhinoceros (Diceros bicornis minor) on a local population of Euphorbia bothae in the Great Fish River Reserve, South Africa
Luske, B.L. ; Mertens, T. ; Lent, P.C. ; Boer, W.F. de; Prins, H.H.T. - \ 2009
African Journal of Ecology 47 (2009)4. - ISSN 0141-6707 - p. 509 - 517.
succulent thicket - height structure - eastern cape - elephant - quality - herbivory - selection - browsers - dynamics - saplings
In the Great Fish River Reserve, South Africa, black rhinoceros (Diceros bicornis minor) feed extensively on a local population of Euphorbia bothae. Maintaining the endangered black rhinoceros and the protected E. bothae population are both conservation priorities of the reserve. Therefore, the sustainability of this plant–animal interaction was investigated by comparing population characteristics, browsing incidence and intensity within the reserve and in an adjacent exclosure without access to rhino. Fixed-point photographs showed that over a 2-month period 36.6% of 213 monitored plants were browsed, with an average biomass loss of 13%, and 1% were destroyed. Of 26 plants re-photographed after approximately 3 years, 70% showed a decrease in biomass, averaging 37.8% over this period. In this time span, 19% of the monitored plants died. Small plants (
A comparison of faecal analysis with backtracking to determine the diet composition and species preference of the black rhinoceros (Diceros bicornis minor)
Lieverloo, R.J. van; Schuiling, B.F. ; Boer, W.F. de; Lent, P.C. ; Jong, C.B. de; Brown, D. ; Prins, H.H.T. - \ 2009
European Journal of Wildlife Research 55 (2009)5. - ISSN 1612-4642 - p. 505 - 515.
fish river reserve - south-african savanna - microhistological analysis - forage quality - subtropical thicket - browsing ruminants - retention times - woody-plants - selection - deer
The diet of black rhinoceros (Diceros bicornis minor) was studied using backtracking and faecal analysis in South Africa. Both methods yielded different results, with a large bias for dominant species. Results of backtracking showed that the rhinos browsed on 80 plant species. Grasses comprised 4.5% of the diet in the faecal analysis, but were not recorded during the backtracking. The backtracking method, along with a measure of forage availability, was used to identify two groups of plant species, those species taken in a higher proportion than available in the field and those taken in a lower proportion. Chemical analyses showed that these two species groups were similar in in vitro digestibility, macro-elements and fibre constituents. Mean bite size and species contribution to the diet were not correlated with any of the forage quality parameters, indicating that rhinos were not maximising nutrient intake or minimising fibre intake of these consumed plant species.
|Livelihoods and landscapes: The people of Guquka and Koloni and their resources
Hebinck, P.G.M. ; Lent, P.C. - \ 2007
Leiden/Boston : Brill Academic Publishers (Afrika-Studiecentrum series vol. 9) - ISBN 9789004161696 - 408
rurale sociologie - plattelandsontwikkeling - landschap - landgebruik - hulpbronnenbeheer - landbouwproductie - teeltsystemen - teelt - wilde planten - sociale verandering - armoede - sociaal welzijn - boerenstand - zuid-afrika - strategieën voor levensonderhoud - natuur - rural sociology - rural development - landscape - land use - resource management - agricultural production - cropping systems - cultivation - wild plants - social change - poverty - social welfare - peasantry - south africa - livelihood strategies - nature
Will tree euphorbias (Euphorbia tetragona and Euphorbia triangularis) survive under the impact of black rhinoceros (Bicornis diceros minor) browsing in the Great Fish River Reserve, South Africa?
Heilmann, L.C. ; Jong, K. de; Lent, P.C. ; Boer, W.F. de - \ 2006
African Journal of Ecology 44 (2006)1. - ISSN 0141-6707 - p. 87 - 94.
manyara-national-park - acacia-tortilis - game reserve - elephant - herbivory - tanzania - ecology - decline - giraffe - damage
The impact of black rhinoceros (Bicornis diceros minor) on the tree euphorbias Euphorbia tetragona and Euphorbia triangularis was studied in the Great Fish River Reserve, South Africa. Black rhinoceros pushed over about 5¿7% of the trees in a 2-month period. There was a preference of rhinos for smaller trees, however this preference did not guarantee euphorbia survival in the larger size classes. This means that tree euphorbias could very well disappear from all areas accessible to rhinos. Rhino feeding choices were correlated with higher plant moisture content, higher nitrogen content, and a higher digestibility