Mc. Rutherford et Lw. Powrie, ALLELOCHEMIC CONTROL OF BIOMASS ALLOCATION IN INTERACTING SHRUB SPECIES, Journal of chemical ecology, 19(5), 1993, pp. 893-906
Aqueous leachates derived from canopy phyllodes of invasive Acacia cyc
lops affected growth of a range of shrub species independently of nutr
ient input effects. All plants showed a sublethal phytotoxic response.
Root mass was generally less adversely affected than shoot mass and,
while decreasing significantly in response to the 10% concentration, s
howed no such response to the 1% solution. Root-shoot biomass ratios i
ncreased, except in Euphorbia burmannii, which may recognize intrinsic
root architecture limitations on extensive exploitation of toxin-free
soil. Application of surface plant litter from under A. cyclops canop
ies stimulated the production of basal stems in Protasparagus capensis
and Eriocephalus racemosus but was insufficient to significantly redu
ce root-shoot ratios. Plant growth inhibition was maximized by canopy
leachate compounded by surface litter effects in Anthospermum spathula
tum. The net effect of leachate at high concentration on biomass alloc
ation in certain shrub species may help explain their patterns of asso
ciation and disassociation with A. cyclops.