Age and growth rate determination using growth rings of selected miombo woodland species in charcoal and, slash and burn regrowth stands in Zambia

Stephen Syampungani¹*, Coert Geledenhuys² and Paxie W. Chirwa³

¹Copperbelt University, School of Natural Resources, P. O. Box 21692, Kitwe, Zambia.

²Department of Forest and Wood Science, University of Stellenbosch, P/Bag X1, 7602 Matieland, South Africa.

³University of Pretoria, Forestry Chair, Postgraduate Studies, Lynwood Rd., Pretoria 0002, South Africa.

*Corresponding author. E-mail: syampungani@cbu.ac.zm,  ssyampungani@yahoo.com.

Accepted July 27, 2010

 Abstract

The field of dendrochronology has not been widely applied in tropical species because many scientists generally perceive that such species rarely produce distinct growth rings. This study was undertaken to determine if the key Miombo species produce distinct growth rings and to determine the relationship between the number of growth rings and age of the tree and stem diameter. The results showed a high correlation between number of growth rings and stand age for both charcoal (P < 0.001, r = 0.9246) and slash and burn (P < 0.001, r = 0.9019) regrowth stands. Additionally, the study has revealed high mean annual ring width values ranging from 4.4 to 5.6 mm in both charcoal and slash and burn regrowth stands. The pattern of ring development per year and the mean annual ring width values provide a basis for the use of ring counts in determining the age of Miombo regrowth stands and predicting the merchantable age for key Miombo woodland species. The results can therefore be used in planning the cutting cycles in Miombo woodlands. However, the phenomenon of missing growth rings suggests that the influence of environment in the use of growth rings in age determination need to be considered in areas that experience droughts.

Key words: Growth rates, growth rings, slope, diameter at breast height and cutting rotations.

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