Figure 1.
A measure of effectiveness for monitoring ecological impact on large trees.
(a) Accumulation curve (mean±95% confidence limits) of tree species within increasing 500 m buffers to determine optimal distance (observed as the point at which the dependent variable levels off) to sample all tree species. Increasing 100 m buffers were used to produce accumulation curves to determine the optimal distance to sample all (b) ecological drivers, (c) elephant use categories and (d) elephant intensity of use categories.
Table 1.
The number of transects and the average distance required to sample five individual trees exhibiting the same type of elephant use, to sample five individuals used or modified by the same ecological driver, to sample five individuals exhibiting use less and greater than six months and to sample five individuals of three locally abundant tree species.
Figure 2.
Accumulation curves (mean±95% confidence limits) within increasing 100 m buffers to determine optimal distance (observed as the point at which the dependent variable levels off) required to sample elephant (a) use categories and (b) intensity of use categories for Acacia nigrescens, (c) elephant use categories and (d) intensity of use categories for Combretum apiculatum and (e) elephant use categories and (f) intensity of use categories for Sclerocarya birrea.
Note the greater variation for single species accumulation curves (compared with Fig. 1) and the increased distance required to approach an optimal transect length.