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Dinteria 28/2003

Dinteria 28/2003

Contributions to the Flora and Vegetation of Namibia
Strohbach, B.J. (ed.)
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Editor: B.J. Strohbach
Series: Dinteria; Number 28, May 2003
Publisher: Namibia Scientific Society National Botanical Research Institute
Windhoek, 2003
ISBN: 99916-40-40-1
Soft cover, 15x21 cm, 48 pages, bw-illustrated


Our note:

Are you interested in writing a contribute for DINTERIA? Please check on the chapter “Author's Guidelines” further down.


Contents:

Cornelia Berry: Aspects of phenology and condition of inland and coastal !Nara plants in the Namib-Naukluft Park, Namibia

Antje Burke: Floristic relationships between inselbergs and mountain habitats in the central Namib

F. P. Graz: Research note: Fire damage to Schinziophyton rautanenii (Schinz) trees in North-eastern Namibia

F. P. Graz: Research note: The Growth of Schinziophyton rautanenii seedlings under different shade conditions

Guide for Authors


Example:

Fire damage to Schinziophyton rautanenii (Schinz) trees in North-eastern Namibia

F. P. Graz
Department of Land Management, Polytechnic of Namibia, P/Bag 13388, Windhoek, Namibia pgraz@polytechnic.edu.na

Abstract:

The nuts of the Mangetti, Schinziophyton rautanenii, are an important food source for a number of rural communities. The environment in which the tree grows, however, is subject torrequent burning. A number of trees have been seen with a characteristic inverted U-shapedfire lesion on the base of the trunk. A collapsed trunk as well as a vertical scar in the same tree showed that heavy branches or a second trunk may collapse under their own weight, thus providing a pointforfire entry.

Introduction:

Fire has been described as an important factor in savannah woodland dynamics and has been the subject of a number of studies. These include the South African Ecosystem Project at Nylsvlei (Scholes & Walker, 1993), the Ndola plots in Zambia (Chidomayo, 1988) and additional fire trials in Northem Namibia (Geldenhuys, 1977). Even now the Directorate of Forestry is in the process of establishing a series of trials near Kanoviei (Louw pers com). The ability of woodland trees to cope with fire varies. Adaptations to deal with fire include thick bark, as may be observed on Schinziophyton rautanenii or Pterocarpus angolensis trees, or the ability to produce coppice shoots. For more information, Rutherford (1981) describes the reaction of a number of other woodland tree and shrub species to fire. While the overall effect of buming on the Vegetation depends on the season and frequency of such bums (Graz, 1996), the effect of fire on individual plants is dependent on the degree to which they are able to recover in the intervals between bums (Trollope 1982). As the interval between bums decreases plants have progressively less time for recovery.

The effect of fire is aggravated by injury to the bark, which allows fire to damage the wood or cambium. Yeaton (1988) observed, for instance, that adult Burkea africana trees would only be affected by a fire when the bark was removed by porcupine (Hystrix species) such that the heartwood was exposed. Fire Damage In north-eastern Namibia fire damage, in the form of hollow stems, can frequently be observed on the trunks of large S. rautanenii trees, while smaller trees show such damage much less often. The hollow is usually open at the base showing a characteristic inverted 'U' shape, such as shown in Figure l.

During a field visit to a stand of S. rautanenii trees it became evident that many trees have multiple trunks, joined at the base. As the crown carried by such trunks grows progressively heavier, the trunk starts to develop vertical checks and Splitting, (see Figure 2). Once a certain mass threshold is exceeded, the trunk breaks off from the remaining tree and collapses. This is clear from Figure 3, showing the opposite side of the trunk in Figure 2.

Once the trunks, or even low branches, have broken off, there is no protective covering of bark to prevent fire scarring. In addition, splinters will provide ideal small size fuel, thus providing fire with a point of entry into the bole. Figure 2 shows the initial stages of fire damage after a large branch has broken from the tree. Charring is evident on the right part of the hole in the trunk. Not so evident on the picture is the extent of the damage at the upper part, where a cavity extends further up into the trunk. Once such a cavity opens at the top, the damaged section acts like a chimney, concentrating the heat within the section, and increasing the rate of damage. Other trees showed profuse coppicing from the base of a collapsed trunk. It is not clear what effect fire may have on the coppice, although it may be assumed that many shoots will be killed.

While it was not verified in the field, it is likely that more female trees are damaged than male trees. The nuts produced by the trees increase the weight of a branch substantially before the fruit are shed, thus causing branches to break. While some authors link the production of fruit crops to rainfall (Graz 2001), Mwamba (1996) reports that nut yield also increases with tree age and size. Keegan (1982) reports that 1t of nuts per hectare were produced by a stand of trees in the Tsumeb forest in northern Namibia.

Despite heavy fire damage trees are able to continue growing and produce fruit. It is unclear at what stage trees are killed. A comparison of the distribution of S. rautanenii given by Graz (2001) and the areas burnt as provided by the Etoscha Ecological Institute show that about 75% of the area in which the species occurs bumt at least once between 1996 and 2000. During the same period approximately 25% of the area burnt annually or biannually. S. rautanenii Stands are often burnt by the local population to facilitate collection of nuts (Tuomasjukka et al. 1998) since collection is made easier when the undergrowth is removed. This trend is likely to continue particularly in view of a increasing human population. Conclusion In the event that Schinziophyton rautanenii is propagated artificially, either through cuttings or seedlings, it will become important to monitor crown form particularly of female trees, and to influence tree development through pruning or planting density. Pruning should reduce trees to single stems that may then grow vertically, and remove such branches that would later break off. In a controlled environment where fire can be excluded, this will also reduce injury to trees in general. However, in places where fire will continue to occur, a modified tree-form will reduce the rate at which trees are damaged or killed.

References:

BÜSCHEL, D. 1999. A study ofresource utilisation: A case from Namibia, Mpungu constituency, Kavango District, northern Namibia.
CRIAA SA-DC Report, Windhoek, Namibia. CHIDOMAYO, E.N. 1988. A re-assessment of effects of fire on miombo regeneration in the Zambian Copperbelt. Journal of Tropical Ecology 4:361- 372.
GELDENHUYS, C.J. 1977. The effect of different regimes of annual burning on two woodland communities in Kavango. South African Forestry Journal 103:32-42.
GRAZ, F.P. 1996. Management of a Pterocarpus angolensis population under the influence of fire and land use. M.Sc. thesis. University of Stellenbosch, South Africa.
GRAZ, F.P. 2001. Description and Ecology of Schinziphyton rautanenii (Schinz) Radcl.-Sm. in Namibia. Dinteria 27:19-35.
KEEGAN, A.B. 1982. Dormancy and Gemination of the Manketti Nut, Ricinodendron rautanenii. Ph.D. Thesis, University of Natal, Pietermaritzburg.
MWAMBA, C.K. 1996. Status report on domestication and commercialisation of non-timber forest products in agroforestry Systems. Tree Improvement Research Centre, National Council for Scientific Research, Kitwe, Zambia SCHOLES, R.J. & WALKER, B.H. 1993. An African Savanna. Synthesis of the Nylsvley Study. Cambridge University Press, Cambridge.
TRAPNELL, C.G. 1959. Ecological results of woodland burning experiments in Northern Rhodesia. Journal of Ecology 49:129-168.
TROLLOPE, W.S.W. 1982. Ecological effects of fire in South African Savannas. In: B.J. Huntley & B.H. Walker (eds) Ecology of Tropical Savannas. Ecological Studies 42:292-306. Springer Verlag.
TUOMASJUKKA, T., TJAVEONDJA, L. & TUBALELE, M. 1998. Proceedings of the 'Kavango forest conservation workshop'. Namibia Finland Forestry Programme, Directorate of Forestry, Windhoek.
VERMEULEN, W.J. 1990. A monograph on Pterocarpus angolensis.
SARCCUS Standing Committee for Forestry, Pretoria, South Africa.
YEATON, R.I. 1988. Porcupines, fires and the dynamics of the tree layer of the Burkea africana savanna. Journal of Ecology 76:1017-1029.


Author's Guidelines:

Editorial policy:

The Dinteria publishes articles in the field of botany related to Namibia. All contributions must be based on original research, must not be under consideration for publication elsewhere, and should constitute a definite advance in knowledge in that field. Authors bear sole responsibility for the factual accuracy of their papers. Referees will review submitted papers and on their advice the Editor will accept or reject contributions. All refereeing is strictly confidential. Articles that contain less than 2000 words may be considered for publication as a Short Note, in which case no separate Introduction, Methods, Results and Discussion are necessary. Short Notes must contain References however, and Acknowledgements may be made if necessary.

Presentation:

Contributions must be written in English. Authors can (optionally) publish a second abstract in a language of their choice. Submit two clear copies of the manuscript, including all drawings, graphs and photographs. For articles that are processed on a computer, please supply also an electronic copy in New Roman font of the manuscript on diskette (or CD), using WORD (6.0 or later) or Rich Text Format (*.rtf). Photographs, figures, drawings and graphs can optionally be submitted in a general graphical form such as Windows Metafiles (*.wmf), GIF (for graphs), JPG or TIF. Please do not embed illustrations into the text. Colour plates may be printed, but the author(s) will have to bear the costs. The layout should conform to the following sequence: Title page with title, author's name(s), address(es) (including, if relevant, an e-mail address), both abstracts, keywords (maximum 8), and then, beginning on a new page.

Introduction, Materials and Methods, Results, Discussion, Acknowledgements and References. Tables (each on a separate page). Captions for Figures (grouped together) and the figures should then follow. All pages must be numbered consecutively, including the title page and those containing references, tables and captions for figures.

Manuscripts should be submitted to:
The Editor: Dinteria, c/o Namibia Scientific Society, P.O. Box 67, Windhoek, Namibia.

E-mail:

nwg@iafrica.com.na, clearly stating that the paper is submitted for publication in Dinteria.

References:

References in the text should be cited as follows: 'Mendelsohn and Roberts (1974) stated ..." or '... (Mendelsohn & Roberts 1997)', when giving a reference simply as authority for a statement. Use the name of the first author followed by et al. when the complete citation involves more than two authors, e.g. 'Schulze et al. (1991)'. A list of publications to which reference has been made in the text must be presented alphabetically according to authors' names and chronologically under each author, with a, b, c, etc. when more than one reference per year from the same author(s) is involved. A personal communication must be confined to the text and not be included in the list of references. In the list, authors' names should be typed in capitals as indicated below.

JANKOWITZ, W.J. 1983. Die plantekologie van die Waterberg Platopark. Ph.D. thesis. University of the Orange Free State, Bloemfontein. MENDELSOHN, J. & ROBERTS, C. 1997. An Environmental Profile and Atlas of Caprivi. Directorate of Environmental Affairs, Namibia. SCHULZE, E.D., LANGE, O.L. & GEBAUER, G. 1991. Carbon and nitrogen isotope ratios of mistletoes growing on nitrogen and non-nitrogen fixing hosts and on CAM plants in the Namib desert confirm partial heterotrophy.
Oecologia 88:457-462. STOCKING, M.A. 1994. Assessing vegetative cover and management effects. In: Lal, R. (ed.), Erosion Research Methods, 2nd edition, pp. 211-232. Soil and Water Conservation Society and St. Lucie Press, Akeny / Delray Beach.

Tables:

Keep tables to a minimum. The same data should not be duplicated in tables and graphs. Each table must be typed on a separate sheet and be numbered consecutively in order of appearance, using Arabic numerals. Pay attention to the limitations imposed by the size of the printed page (A5).

Illustrations:

Please do not embed illustrations in the text, but submit these separately. The rules for numbering are the same as for tables. Photographs must be of a good quality on glossy paper, with clear details and adequate contrast. Please contact the editor if slides are to be reproduced. Drawings, diagrams and graphs should be done in black India ink on good-quality paper or tracing film. An illustration may not exceed twice the linear dimensions desired in the final reproduction. Allow space for the caption when presenting a figure that will occupy a whole page. It is important that lines and symbols be drawn sufficiently boldly to withstand reduction. The size of the lettering on the original must be such that the letters will be about 1.8 mm high after reduction. If the author(s) require a figure to be reproduced without reduction, this is to be clearly indicated. It is, however, recommended that use be made of a scale bar on figures. Write in soft pencil, the name of the author(s) and the figure number, as well as an arrow indicating the top of the figure on the reverse side. Place captions of figures collectively on a separate sheet of paper.

Reprints:

Dinteria supplies, free of charge to the author(s), 10 reprints of each full-length paper.