Mgambo Forest Reserve: A biodiversity survey. - Eastern Arc ...

Mgambo Forest Reserve
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4.3.2 Disturbance transects
A total area of 13.635 ha was assessed for signs of disturbance. Disturbance categories were
recorded for all 50m sections along each transect line. Every self standing tree (not creepers or
lianas) above 5cm diameter at breast height (dbh) was measured within a distance of 5m either
side of each transect line. Each plant was recorded under one of four categories: live, old cut, new
cut or naturally fallen. Old cut was identified by darkening and rotting of a cut stump, and was
assumed to have been cut more than 6 months prior to sampling. New cut was identified by fresh
cream or green cut stumps and assumed to have been cut less than six months prior to sampling.
Within these categories a distinction was made between poles and timbers. Poles were classified
as having a dbh between 5 and 15cm and a minimum 3m relatively straight trunk. Timber was
classified as having a dbh greater than 15cm with a minimum of 3m relatively straight trunk.
These divisions are based on differences in use. Timber and pole cutting data are presented as an
average per hectare.
All other forms of anthropogenic disturbance within a distance of 5m either side of each transect
were also recorded for every 50m section.
Other forms of disturbance were defined as follows:
Fire damage - an area affected by fire, evidence included burnt trees and ground vegetation.
Pitsaw site - an area cleared for pitsaw activities, with pitsaw platform, or remains of such.
Timber/planks/poles - cut wood on ground abandonned or ready for transportation.
Trapping - animal traps of all varieties whether set or sprung or unused.
Cultivation - evidence of crop cultivation (past or present).
Grazing - direct evidence or remains of cattle grazing.
Roads/tracks - including all human used footpaths.
Old Settlement - well-established clearings as a consequence of past human settlement.
The topography of Mgambo FR was generally not difficult and, consequently, only one 50m
section was found to be inaccessible. A total of 10949 live stems were sampled throughout the
reserve, giving a mean total of 613.7 poles per hectare and 189.3 timbers per hectare, 76% and
24% respectively.
4.3.2.1 Pole and Timber extraction
Pole and timber extraction was found along all seven transects, however, new extraction was only
observed at a low intensity within the reserve.
Rates of pole extraction are summarised in Table 15 and Figures 11 and 13. An average total of
3359 poles per hectare were alive, 695 dead and 198 cut, representing 79%, 17% and 4% of all
poles sampled respectively (Table 15). None of the transects had a significantly higher rate of
extraction than the others. (Figure 11). A significant proportion of the poles sampled were dead,
particularly along transects 0 and 1 (Figure 13). Live poles were least abundant along transect 6
with 291 poles per hectare compared with all of the other transects with figures over 450 poles per
hectare. (Table 15 and Figure 11).
Pole cutting was most intensive along reserve border areas (Figure 15). A high level of extraction
was observed within proximity to Daluni and Bwiti villages to the south of both halves of the
reserve (see Figure 3 for positioning of villages).
East Usambara Conservation Area Management Programme Technical Paper 59