In this study, researchers quantified the density and complexity
of understorey flora of old growth forest and of selectively logged, fragmented
and regrown forest. They determined various parameters from standardized
photographs from these forests, and calculated correlation between these
parameters.
The researchers selected two sites from a forest in Malaysia (primary and
logged) and randomly selected 14 study points from grids of each of the
sites. They then took photographs in the N, S, E, and W directions from
the points. The photographs were then displayed such that only the borders
and interiors of vegetation became significant.
The parameters were:
• core area: (total are of vegetation patches) - (outermost pixel from
all patch edges)
• number of patches: number of discrete vegetation patches
• mean patch size: mere area of vegetation patches
• patch size standard deviation
• total edge: sum of the edge lengths of vegetation patches
• landscape shape index: (sum of edge segments) / (square root of total
area of image)
• average weighted mean shape index: (patch perimeters) / (square root
of patch areas) and
• average weighted mean patch fractal dimension: 2*log(patch perimeter)
/ log(patch area) * (patch area) / (sum of the area of all patches)
The parameters measuring patch density auto correlated strongly, as did
those for patch complexity. However there were no significant correlations
between the parameters for density and complexity.
In general, the logged forest tended to be denser than the primary forest,
partly because the logged forest resembles areas of primary forest in which
natural tree falls cause a naturally denser understorey. The logged forest
showed much less variance in density and complexity, and thus indicated
a loss of heterogeneity.
Analyzing understorey density and comlexity in this fashion could be an
important tool in studying animal and plant habitat associations.