[en] Landscape Ecological Survey of the Bipindi-Akom II ... - ITTO

and 4d were joint to make a single topographic map of the TCP area. The topographic map was
updated as for the location of logging roads with the aid of a Global Positioning System (GPS).
Black & white aerial photographs photographs of the TCP area were were taken in 1963-66 1963-66 at a scale scale of 1 :50,000
and in 1983-85 at a a scale of of 1 :20,000. The The 1963-66 series has insufficient contrast to to allow allow for
stereoscopic vision. The much much better better quality photographs of the 1983-85 series have therefore
been used for photo interpretation in the present survey. A list of the photographs is presented
in Annex Annex Ill. Ill.
The interpretation interpretation of the aerial photographs resulted in the drafting of preliminary preliminary maps on
landforms and vegetation at a scale 1 :50,000 (Touber, 1993a). The maps have have hierarchical
legends and discern a total total of 49 and 25 legends units, respectively. A five week mission to the
TCP TCP research area was carried carried out out in 1993 and sites were selected for the efficient sampling of
the most important land land units in the area (Touber, 1993b).
3.3 FIELDWORK
3.3.1 General
Observation sites were selected on the basis of the photo interpretation maps. Fieldwork
involved the description of the attributes of the units discerned by photo-interpretation.
Fieldwork was not merely a check check to verify verify the photo interpretation as it largely largely entailed the
collection of new information.
The land units sampled were considered the most important and widespread in the TCP area.
The actual sample sites were selected on the basis of representativeness representativeness and accessibility.
accessibility.
Transects, or transverses, of one to two kilometres with a general orientation perpendicular to
the contour lines, have have been been laid out. These transects provided access access to the land units units to to be be
described and enabled the detection of possible catenas or toposequential processes. Within the
transect three to seven observation points were selected for detailed description. The locations
of the the observation observation points were determined by both the soil surveyor and the vegetation
specialist. At each sampled locality, landform, soil and vegetation characteristics characteristics were
described. In Fig. 3.1 the the distribution distribution of observation points in the TCP research research area is is given.
During the field work the survey team consisted of of a soil surveyor, a vegetation surveyor, a field
botanist (part-time), a local tree spotter and a local local soil survey assistant. The The transects were were laid laid
out by a a 'compass man' and two line line cutters recruited from the nearest village. The distance distance
along the the transects was measured measured with with a 'Topofyl' and each hundred hundred meter was (temporarily)
marked with with a pole. The survey team covered approximately one kilometre per day day for normal
sampling procedures. One or or two days extra were needed to dig and describe soil pits. pits.
All transects and observation points have geographical coordinates and can be retraced on the
base map and the aerial photographs. Photo interpretation and fieldwork were not strictly
separated in time; efforts have been made to study the aerial photographs after each period of
fieldwork and to adjust the preliminary legends and maps to the insights gained.
The sampling procedures for landform, soil and vegetation aspects are discussed in in the sections
3.3.2 and 3.3.3.
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