Is the removal of domestic stock sufficient to restore semi-arid conservation areas?

Increasingly, conservation areas are proclaimed in non-pristine environments that have biodiversity values and the issue of how to change the management regime to restore such landscapes arises. Before gazettal in 1992, Currawinya National Park (28°52'S, 144°30'E) in south-west Queensland's mulga lands was grazed by domestic stock for over 130 years. Following gazettal, the area was destocked and a monitoring programme initiated to determine the response by the vegetation. This paper describes the grass dynamics in three vegetation communities on Currawinya National Park with three different grazing regimes. Data are presented for an on-park site (native and feral herbivores present), an off-park site (domestic, native and feral herbivores were present), and an exclosure (no mammalian herbivores present). The results show that removal of domestic livestock alone is not sufficient to promote rapid recovery of grass populations, and suggest that conservation area managers must reduce native herbivore numbers as well if the desired outcome is a return to the supposed "natural" condition

Precipitation and Fire Effects on Flowering of a Rare Prairie Orchid

A small, isolated population of the threatened western prairie fringed orchid (Platanthera praeclara Sheviak & Bowles) occurs at Pipestone National Monument, Minnesota, in a mesic prairie that is periodically burned to control invasive cool-season grasses. During 1995-2004, monitoring counts of flowering orchids in the monument varied considerably for different years. Similar precipitation amounts in the spring and histories of burning suggest that fire and precipitation in the spring were not the causes of the variation. For the eight non-burn years in the monitoring record, we compared the number of flowering plants and the precipitation amounts during six growth stages of the orchid and found a 2-variab1e model (precipitation during senescence/bud development and precipitation in the dormant period) explained 77% of the annual variation in number of flowering plants. We also conducted a fire experiment in early May 2002, the typical prescribed burn period for the monument, and found that the frequency of flowering, vegetative, and absent plants observed in July did not differ between burned and protected locations of orchids. We used the model and forecasts of precipitation in the spring to develop provisional burn decision scenarios. We discussed management implications of the scenarios

Economic and environmental analysis of fodder harvesting practices associated with mulga (Acacia aneura) and fire management practices in the mulga lands of south western Queensland

The project was funded by the Australian Government, Department of the Environment, Water, Heritage and the Arts, and was bounded within the 18.1 million hectares of Queensland's mulga lands. The time frame of the project was 18 months. Consequently, long term real-time approaches to data collection were not possible. A natural experiment model was adopted investigating a representative range of recent and historical practices using 'time since action' as a temporal surrogate. An initial stage of the project identified and detailed the current and historical range and extent of management practices associated with mulga fodder harvesting in the region. Local landholders were recruited and participated in group interviews to draw on experiential local knowledge. Outcomes of group interviews were used to develop a clear understanding of fodder harvesting practices in the region and classify the range of practices into a manageable number of scenarios for further site specific investigation. The financial costs and returns associated with different methods of fodder harvesting were modelled and compared to alternative management strategies that landholders may employ if fodder harvesting was not an option. The strategies compared were harvesting, agistment of stock elsewhere, and selling (and re-purchasing) stock. The economic modelling was based on six case properties that were derived from survey data provided by landholders

Is 'vegetation thickening' occurring in Queensland's mulga lands - a 50-year aerial photographic analysis

Changes in the density of woody vegetation in arid and semiarid rangelands have the potential to dramatically reduce productivity as well as adversely affect ‘natural’ ecosystem processes. Many parts of Australia are believed to have experienced thickening of woody vegetation since European occupation and the associated changes to fire and grazing regimes that followed. Unfortunately there is little empirical evidence to support a widely held perception of thickening. This study analyses the available historical aerial photographic coverage for the mulga lands bioregion of south-western Queensland, Australia; a record spanning the second half of the twentieth century. Changes in woody vegetation canopy cover were assessed for 190 sites. More than half of the sites had no evidence of mechanical disturbance and thus reflected general, or background trends in woody vegetation cover. The region-wide average extent of change on these undisturbed sites was estimated to be approximately a 3.6% increase in canopy cover over the study period. Thus, a trend toward vegetation thickening was detected. However, large variation was observed depending on the land systems and rainfall zone where sites were located. The results are discussed in the context of century scale climate variability and perceptions of vegetation change and a tentative explanatory model is presented to account for the observed data