Vegetation change in an urban grassy woodland 1974 - 2000

Abstract

Few temporal studies document vegetation change in Australian temperate grassy woodlands. Floristic and structural data were collected from 68 randomly located sites in the Queens Domain, an urban grassy woodland remnant, in 1974, 1984, 1994 and 2000 and a search made for rare species. Species of conservation significance were concentrated at highly disturbed sites, whereas vegetation types of conservation significance decreased in area as a result of increases in the numbers of Allocasuarina verticillata, which caused a change in many unmown areas from Eucalyptus viminalis grassy woodland to E. viminalis–A. verticillata woodland/forest or A. verticillata open/closed forest. Structural changes were associated with changes in species composition and an increase in native-species richness. Increases in tree cover occurred where fires were most frequent, possibly as a result of the lack of mammalian herbivores. The frequencies of herbs and annual grasses were strongly affected by precipitation in the month of sampling. Half of the species that showed a consistent rise or fall through time were woody plants, approximately twice the number expected. In the dataset as a whole, species-richness variables were largely explained by varying combinations of variables related to moisture availability, altitude and the incidence of mowing. The strongest influences on species composition were the same, although slope and time since the last fire also contributed to multiple regression and generalised linear models. Compositional stability was positively related to native-species richness, whereas high levels of exotic-species richness occurred at both low and high levels of native-species richness. The maintenance of native-plant biodiversity on the Domain requires such counterintuitive measures as the maintenance of exotic trees and the control of native trees, demonstrating the contingencies of conservation management in fragmented vegetation that consists of a mixture of native and exotic species.

Long‐term livestock exclusion facilitates native woody plant encroachment in a sandy semiarid rangeland

“…Coincidentally, the same phenomenon has been observed in temperate savanna (Weltzin et al. ), temperate grassy woodland (Kirkpatrick ), grassland (Noble et al. ), and other areas.…”

Functional traits and prior abundance explain native plant extirpation in a fragmented woodland landscape

“…Additionally, climatic conditions in the year of observation (e.g. rainfall amount and timing) can affect the likelihood of detecting seasonal species such as annuals (Kirkpatrick 2004; Dostal 2005) and geophytes (Lesica & Steele 1994; Morgan 1998). Many of these inherent limitations, however, can be reduced when vegetation is sampled at multiple times across a year.…”

The positive and negative conservation impacts of sheep grazing and other disturbances on the vascular plant species and vegetation of lowland subhumid Tasmania

“…The absence of sheep grazing also seems likely to lead to the local extinction of some species on fertile sites with deep soils. On the ungrazed Domain it was only the annual species that required large scalds that became extinct after the cessation of grazing, but many other species only survive on the Domain in places where shallow rocky soils or intense physical disturbance limit above‐ground competition (Kirkpatrick 2004).…”

“…As Lunt and Morgan (2002) point out, fire is only one means of gaining the tussock biomass reduction that allows the persistence of light‐demanding herbaceous species that lack a persistent soil seed store. Unfortunately, on the Domain, frequent fire over several decades, in the absence of grazing, has increased the abundance of woody plants (Kirkpatrick 2004; Kirkpatrick and Bridle, unpubl. data, 2004), rather than the reverse situation often postulated (Lunt & Morgan 2002).…”