Life-History Attributes of Plants in Grazed and Ungrazed Grasslands on the Northern Tablelands of New South Wales

Abstract

The composition, diversity and structure of unfertilised temperate grassy communities were compared, after adjacent areas had been grazed or left ungrazed for 16 years. Life-history attributes of species in the two communities were also compared. Most species in both treatments were forbs, but these generally occurred with low frequencies and grasses formed the vegetation matrix. Native and perennial species predominated, reflecting pre-European conditions. Long-term, continuous grazing by sheep had opened the grass and litter canopy, promoted species richness and favoured a suite of morphological plant characteristics. Thus, species with dormant meristematic tissue at or below ground level, forbs of low stature and small tufted grasses were relatively common. The ungrazed treatment was densely vegetated, relatively species-poor and plants tended to have morphological attributes opposite to the above. A later, double-peaked flowering period in the ungrazed community was explained by the greater proportion of native perennials, versus the more common early-flowering exotic annuals in the grazed community. The larger proportion of vegetatively reproducing forbs in the ungrazed treatment reflected the density of the vegetation and the possible absence of appropriate sites for regeneration by seed, or the heterogenous distribution of resources available to interstitial plants.