Marloth Park Management Plan. - Nkomazi Local Municipality

OBJECTIVES
The objectives of this study are to:
METHOD
• Determine the tree density within the different homogenous units.
• Determine the leaf production and of the various woody species in the
homogenous units.
• Determine the available browse and browsing capacity of the different
homogenous units.
Due to the factors that determine available browse such as variability in leaf density,
palatability and tree structure, it is difficult to find a method that combines applicability and
practicability. Different methods for determining browse have been developed and assessed
over time. The belt transects have been found to be more accurate and less biased than plot
surveys – at least in canopy cover estimates for woody vegetation. With the BECVOL model
it is possible to set up a standard procedure to measure browse potential and browse capacity
using fairly simply measurements while still obtaining a sufficiently accurate estimation.
To determine the total volume of woody plant material in this study the BECVOL method is
applied, where the volumetric dimensions of trees are recorded and related to available leaf
biomass. The measurements taken are based on an ideal tree, which is regarded as a single
stemmed sweet thorn Acacia karroo with a canopy consisting of a dome-shaped crown and
cone-shaped base (Figure 11). These measurements are recorded for each tree rooted and
identified in a 200 m 2 belt-transect survey. A 2 m long range-rod is used to estimate the tree
dimensions.
The data collected is then captured and analysed using the BECVOL programme. Primary
analysis consists of volumetric calculations to determine the total leaf volume of each tree
species recorded. The total leaf volume is then related to potential dry leaf mass, based on
known regression equations from harvested trees. Although common bushveld tree species
such as sweet thorn Acacia karroo, red bushwillow Combretum apiculatum, sickle bush
Dichrostachys cinerea, raisin bush Grewia species and silver cluster leaf Terminalia sericea
have specific regression equations, it was found that a strong correlation exists between some
of these tree species based on leaf size. Other tree species were thus related to standard
regression equations based on this phenomenon. For other tree species general regression
equations are based on either microphyllous (small-leaved) or macrophyllous (broad-leaved)
tree species.
© Ecological Associates/ Marloth Park 47