S. Mcintyre et al., PLANT LIFE-HISTORY ATTRIBUTES - THEIR RELATIONSHIP TO DISTURBANCE RESPONSES IN HERBACEOUS VEGETATION, Journal of Ecology, 83(1), 1995, pp. 31-44
1 Species composition and disturbance state (level of soil disturbance
, grazing and water addition) were recorded for 120 (30-m2) plots in t
emperate grassland of the New England Tablelands (Australia). Three di
fferent classificatory schemes were used, based on (a) life-form (sens
u Raunkiaer); (b) dispersal unit morphology and (c) vegetative reprodu
ction. We analysed the effects of the different disturbance types and
intensities on number and proportion of species belonging to these gro
ups. The results were used to describe the spectrum of life-histories
likely to be present at sites in different states of exogenous disturb
ance. 2 Soil disturbed sites had proportionately more therophytes, ver
satile/flat rosettes and wind dispersed species. Two features are like
ly to lead to success in soil disturbed sites: ability to colonize ope
n space (e.g. therophytes, wind dispersal) and capacity to capture res
ources effectively (e.g. flat architecture of rosettes). Non-disturbed
sites had more geophytes, chamaephytes, phanerophytes, proto-hemicryp
tophytes and erect rosettes, with greater numbers of vegetatively repr
oducing species. 3 Heavily grazed sites had higher proportions of ther
ophytes and versatile/flat rosettes and species with mobile seeds than
sites with light grazing. Moderately grazed sites had increased propo
rtions of versatile and erect rosettes and more species with adhesive
seeds (mainly grasses). Lightly grazed sites had a greater diversity i
n terms of evenness of all life-forms, dispersal morphologies and repr
oductive modes. 4 Water enriched sites had fewer geophytes and phanero
phytes and some chamaephytes, erect rosettes and proto-hemicryptophyte
s. This loss was only partially compensated by a gain in versatile and
partial rosettes but richness decreased overall. Water enrichment was
unrelated to dispersal unit morphology or the potential for vegetativ
e reproduction. 5 Of the three attributes examined, life-form was most
useful in characterizing community response to different disturbance
types. Traits related to regeneration (seed morphology and capacity of
vegetative reproduction) were relevant to soil disturbance only. Our
results support the use of such classifications for monitoring the eff
ects of disturbance.