Faculty of Science
School of Animal Plant and Enviromental Sciences
0404336v
lmcnamara@gpf.co.za / Pine saw timber plantation forestry on the Eastern Escarpment of South
Africa contributes significantly to the economy of the country. Losses to
plantation value through fire, insects and disease, and particularly over the
last decade, losses due to baboon damage are of serious concern.
Anecdotal evidence indicated that baboons damage pine trees shortly
following pruning operations and at certain times of the year. A perception
existed that damage has increased dramatically, yet no documented
evidence to this effect is available. As a result two physiological studies were
undertaken to investigate whether changes in nutrient concentration of inner
bark tissues of pine trees on the Eastern Escarpment of South Africa, act as
triggers for baboon damage. A literature review was also undertaken to
document the extent of baboon damage, tree volume and associated
economic costs. A comparison was made with Zimbabwe, where baboon
damage is quoted to be a severe threat to the continued viability of plantation
forestry.
The first study investigated changes in nutrient concentration of the soft, inner
bark tissue of Pinus patula, in response to pruning measured in five year old
plantations in the Mpumalanga Province, South Africa. Samples of tissues
were collected from pruned and unpruned trees at 2, 7, 14 and 28 days after
26% of the live crown had been removed in the pruning treatment. Results
indicated that live pruning of Pinus patula did not influence nutrient
concentration of inner bark tissues at set intervals post pruning. Treatment
differences of aggregate data for sample interval showed that potassium
concentration increased by 0.03% whereas magnesium concentration
decreased by 0.02% following pruning. Aggregate data for treatment showed
that phosphorus, carbohydrates (fructose, glucose, sucrose and starch),
boron and nitrogen concentration, and moisture content of inner bark tissues
varied during the short time period of the study. Variations are attributed to
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the commencement of growth, translocation of nutrients from needles and
branches and possibly moisture stress. Results from the study do not support
anecdotal evidence that baboon damage to pine plantations which increases
shortly after pruning operations is as a direct physiological response to the
pruning event. In this study it is much more likely that changes in nutrient
concentrations coincided with a remobilization of resources in response to
seasonal triggers.
In the second study, nutrient concentrations of the inner bark of Pinus patula
and Pinus taeda growing on the Eastern Escarpment of South Africa were
studied over a seasonal cycle in order to investigate the allegations that
baboon damage in the plantations was related to the degree of nutrient
remobilization. Significant differences were found in phosphorus
concentration and moisture content across seasons and between baboon
damaged and undamaged trees. Undamaged Pinus taeda trees recorded the
highest phosphorus levels in April 2003 (0.13%). Moisture content was
lowest in damaged Pinus patula trees in August 2003 (57%). Anecdotal
evidence that baboon damage to pine trees on the Eastern Escarpment of
Mpumalanga increases prior to the growing season is supported by the
significant changes in inner bark tissue concentration. Nutrient translocation
prior to needle fall alters inner bark nutrient concentration, as does moisture
stress and demand for nutrients prior to cambial activity. Pine bark is easier
to peel during periods of peak cambial activity. These factors are discussed
as they may trigger baboon damage. Significantly higher inner bark tissue
concentrations of sucrose (4.25 versus 2.61%), starch (4.75 versus 2.84%)
and nitrogen (0.61 versus 0.49%) in Pinus taeda compared with Pinus patula,
supports anecdotal evidence that Pinus taeda is preferentially damaged by
baboons. Baboon damaged trees contained higher concentrations of zinc
(30.4 versus 22.3 ppm) and calcium (0.26 versus 0.20%), and lower
concentrations of sucrose (2.95 versus 3.91%) and starch (3.21 versus
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4.39%) than undamaged trees, which was attributed to resource allocation to
wound response and not that baboons selected trees with higher
concentrations of zinc or calcium. The variability of inner bark tissue
concentration due to a number of factors highlights that baboon damage in
pine plantations is not readily answered, and remains a complex problem.
A literature review was undertaken of reported baboon damage occurrence
and intensity of damage, following statements that baboon damage to pine
plantations is rapidly escalating in the Mpumalanga Province, South Africa.
The extent and intensity of baboon damage from the first reported damage
(1960’s) until current levels are documented. A comparison is made between
Zimbabwe and South Africa where the baboon damage is viewed as a
serious problem. The extent of baboon damage in Zimbabwe, expressed as
the total percentage of area damaged by baboons as a function of the total
area planted to pine for the period 2000-2004 has escalated from 10.8 to
13.3% despite harvesting activities removing damaged trees (Fergusson,
2004). The total area with reported baboon damage in Zimbabwe amounted
to 5 317 hectares in 2004 (Fergusson, 2004). In South Africa baboon
damage has increased markedly from the first reports of 300 hectares in 1980
(Bigalke, 1980) to 7 641 hectares in 2004. The average percentage of trees
damaged in affected compartments is 20.4% with the percentage increasing
from 17.2 to 23.6% from 2002-2004. Pinus taeda appears to be the most
severely affected species with Pinus elliottii showing increasing levels of
damage in many compartments in 2004. Quantifying the value lost by
baboon damage to the industry requires reliable assessment methods that
are cost effective to implement. Assessment methods need to take into
account the position of the damage on the stem, and resultant saw log value
that is lost. Assessment methods implemented in South Africa and
Zimbabwe are described, and results given by method applied. A standard
assessment method is required for comparisons to be made between areas
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with baboon damage. An investigation in Zimbabwe highlighted significant
differences between standing tree volume estimations (4.98 – 7.59 m3/ha,
with various methods), and actual volume losses (50.45 m3/ha) (Ngorima et.
al., 2002). The associated Rand value loss determined by the South African
assessment method in 2004 was in excess of 20 million Rand. This
estimated loss in revenue does not include losses of incremental growth due
to the damage, re-establishment costs, loss of thinning and clearfelling
product revenue due to timber wastage, or losses experienced in down line
processing at the saw mill. The extent of the baboon damage problem
warrants proactive management, continued monitoring and investment into
research in order to gain a better understanding of the problem. The increase
in the extent of baboon damage from early documented figures is most
alarming, showing that the baboon damage problem continues to grow.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/1493 |
| Date | 27 October 2006 |
| Creators | Mcnamara, Lorraine |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 2085436 bytes, application/pdf, application/pdf |
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