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Competition among canopy trees in indigenous forests: An analysis of the ‘additive basal area’ phenomenon
Author(s) -
Midgley J. J.,
Parker R.,
Laurie H.,
Seydack A.
Publication year - 2002
Publication title -
austral ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.688
H-Index - 87
eISSN - 1442-9993
pISSN - 1442-9985
DOI - 10.1046/j.1442-9993.2002.01177.x
Subject(s) - basal area , canopy , competition (biology) , basal (medicine) , ecology , interspecific competition , biology , geography , insulin , endocrinology
The basal area of indigenous forest plots containing large canopy individuals appears to be larger than plots without them. One explanation for this effect is the avoidance of competition for light due to these large individuals emerging above the rest of the canopy and thus casting relatively little shade. In this way the basal area of these emergent individuals becomes ‘additive’ to that of the ‘rest’ of the individuals on a plot. The ‘additive basal area’ phenomenon was tested for in the Knysna Forest, South Africa by regressing the basal area of focal species versus the total basal area of 0.04‐ha plots, as well as against the basal area of the ‘rest’. Regression analysis suggested weak competition and a stronger additive effect. However, no emergent individuals occurred in the study taxa. A strong impact of the size of the largest individual on total plot basal area was found. It is suggested that the reason for this is that large individuals overcome spatial and packing limitations in forests.