Mlinga Forest Reserve: a biodiversity survey. - Coastal Forests of ...

Mlinga Forest Reserve
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4.2.1.3 Disturbance transects
Disturbance transects were used to record the intensity of pole and timber cutting and
incidence of other disturbance types in the forest reserve. The disturbance transects were
based on the 450m x 450m grid prepared for the vegetation plots (Figure 3). Each transect
running east-west was sampled from border to border where accessible. Disturbance was
recorded by 50m section along each transect.
Every self-standing tree and sapling (not lianas or creepers) above 5cm dbh was measured
within 5m either side of each transect line. Each plant was recorded under one of four
categories: live, old cut, new cut or naturally dead. Within these categories a distinction was
made between poles and timbers. Poles were classified as having a dbh (diameter at breast
height) between 5 and 15cm and a minimum of 2m relatively straight trunk. Timber was
classified as having a dbh > 15cm with a minimum 3m relatively straight trunk. These
divisions were based on differences in use. New cut stems were determined by cream
coloured slash and classified as freshly cut within recent months (approximately within the
past 6 months). Old cut stems were determined by black coloured slash and classified as old
cut (approximately more than 6 months old). Timber and pole cutting data are presented as an
average per hectare and summarised in graphs and maps.
The incidence of other signs of disturbance (such as fire, cultivation, animal trapping,
pitsawing) were documented every 50m section and summarised in a table and maps. The
most disturbed plots were calculated using pole and timber cutting counts and incidence
figures for ‘other signs of disturbance’. Pole and timber cutting counts were combined,
summed and then ranked, with the most disturbed plot ranked 1. All incidence records of
‘other signs of disturbance’ were summed and ranked, with the most disturbed plot ranked 1.
The top six plots in each data set were combined to give the top twelve disturbed plots. Three
additional border plots were additionally considered to be worthy of consideration.
)
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`15
14
14A
Transect 0
1 2
3
4 4A
Transect 1
24 23 22
21
20 19 18
17
17A
Transect 5
7 6 5
4
10
9
9A
Transect 2
29
28 27A
27 26A
26
25
Transect 6
11
12 13
33 34
34A
Transect 3
Key:
30
Transect 7
13
Vegetation Plot
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32
Transect 4
34A
Incomplete 450m sections
Scale:
Accessible transect lines
450m
450m
Figure 3 Location of vegetation plots and disturbance transects in Mlinga FR.
(GPS co-ordinates of vegetation plots are summarised in Appendix 2).
East Usambara Conservation Area Management Programme Technical Paper 56