Forest and Rangeland Ecosystems

Beecroft, Australia

Forest and Rangeland Ecosystems

Beecroft, Australia
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Cowie A.L.,University of New England of Australia | Penman T.D.,Forest and Rangeland Ecosystems | Gorissen L.,Flemish Institute for Technological Research | Winslow M.D.,Indian International Crops Research Institute for the Semi Arid Tropics | And 9 more authors.
Land Degradation and Development | Year: 2011

The United Nations Convention to Combat Desertification and its sister conventions, the United Nations Framework Convention on Climate Change and the Convention on Biological Diversity, all aim to halt or mitigate the deterioration of the ecological processes on which life depends. Sustainable land management (SLM) is fundamental to achieving the goals of all three Conventions. Changes in land management undertaken to address dryland degradation and desertification can simultaneously reduce net greenhouse gas emissions and contribute to conservation of biodiversity. Management to protect and enhance terrestrial carbon stocks, both in vegetation and soil, is of central importance to all three conventions. Protection of biodiversity conveys stability and resilience to agro-ecosystems and increases carbon storage potential of dryland systems. SLM improves livelihoods of communities dependent on the land. Despite these complementarities between the three environmental goals, tradeoffs often arise in their pursuit. The importance of human-environment interactions to the condition of land compels attention to adaptive management. In order to reconcile concerns and agendas at a higher strategic level, identification of synergies, conflicts, trade-offs, interconnections, feedbacks and spillover effects among multiple objectives, drivers, actions, policies and time horizons are crucial. Once these issues are transparent, coordinated action can be put into place across the three multilateral environmental agreements in the development of strategies and policy measures to support SLM. Copyright © 2011 John Wiley & Sons, Ltd.

Adams M.D.,University of Wollongong | Law B.S.,Forest and Rangeland Ecosystems
Australian Zoologist | Year: 2011

The management of native regrowth forests for biodiversity has become increasingly important in recent years, as most old growth forest on mainland Australia is now protected and logging operations occur primarily in regrowth. Regrowth forest typically has higher stem density than old growth; therefore, bats (Microchiroptera) adapted to foraging along edges and in open spaces are likely to be less active in regrowth forest. Thinning is an integral component of regrowth management and could reduce structural clutter to a level suitable for bats with a range of clutter tolerances; yet little is known about the effects of thinning on bat activity, especially in Australia. In a preliminary study, we compared the activity levels of all bats, one open-space and three edge-space aerial foraging bat guilds in unthinned (n = 3) and thinned (n = 3) regrowth, in forests managed for timber production on the south coast of New South Wales. We measured bat activity at three heights in the forest (understorey, subcanopy and canopy). The number of volant insects (prey items) was also measured at each site/height combination, while 20 structural vegetation variables were measured at each site. A total of 263 bat passes was recorded in 18 detector-nights. We found high variability in bat activity for all bats and guilds between regrowth treatments and among heights, and no significant difference between levels of these factors.There was no significant interaction between logging and height factors. Vegetation structure varied significantly between unthinned and thinned sites for just two variables: the shrub layer had a higher percentage cover, and the vertical gap between canopy and understorey trees was halved, in thinned regrowth. Multivariate analysis of vegetation structure suggested just a small increase in the distance between canopy and understorey tree stems and slightly less cover in the canopy in thinned sites, changes that would represent a reduction in clutter. With the highest density of stems, the understorey of both regrowth types represented the most cluttered stratum for bats and overall bat activity was lower there (though not significantly). However, total bat activity did not indicate a clear response to insect abundance in the less cluttered subcanopy and canopy. Although the variability in bat activity within our regrowth treatments was too high to unequivocally state that thinning had no effect, results obtained from older regrowth of the same forest type suggest that overall activity is low for bats in dense regrowth forest, and that the level of thinning conducted at our sites was not sufficient to increase levels of activity consistently. We review the scientific literature on thinning effects for bats and formulate more specific hypotheses for future testing. Appropriate measures of clutter need to be identified to incorporate into indices of stand structural complexity that are relevant for bats.

Penman T.D.,Forest and Rangeland Ecosystems | Penman T.D.,Bushfire Cooperative Research Center | Beukers M.,Parks and Wildlife Group | Kavanagh R.P.,Forest and Rangeland Ecosystems | Doherty M.,CSIRO
Applied Vegetation Science | Year: 2011

Question: Are long-unburnt patches of eucalypt forest important for maintaining floristic diversity? Location: Eucalyptus forests of southeastern New South Wales, Australia. Methods: Data from 976 sites representing a range of fire history from three major vegetation formations - shrubby dry sclerophyll forest (SF), grassy dry SF and wet SF - were analysed. Generalized linear models were used to examine changes in species richness with increasing time since wildfire and analysis of similarities to examine changes in community composition. Chi-squared tests were conducted to examine the distribution of individual species across four time since fire categories. Results: Plant species relationships to fire varied between the three formations. Shrubby dry SF supported lower plant species richness with increasing time since wildfire and this was associated with shifts in community composition. Grassy dry SF showed significant shifts in community composition and species richness in relation to time, with a peak in plant species richness 20-30yr post fire (either prescribed fire or wildfire). Wet SF increased in species richness until 10-20yr post wildfire then displayed a general declining trend. Species richness in each vegetation type was not related to the fire frequencies and fire intervals observed in this study. Conclusions: Long-unburnt (30-50yr post wildfire) forests appeared to play a minor role in the maintenance of plant species diversity in dry forest systems, although this was more significant in wet forests. Maintenance of a range of fire ages within each vegetation formation will assist in maintaining floristic diversity within regions. © 2010 International Association for Vegetation Science.

Penman T.D.,Forest and Rangeland Ecosystems | Penman T.D.,University of Wollongong | Price O.,University of Wollongong | Bradstock R.A.,University of Wollongong
International Journal of Wildland Fire | Year: 2011

Wildfire can result in significant economic costs with inquiries following such events often recommending an increase in management effort to reduce the risk of future losses. Currently, there are no objective frameworks in which to assess the relative merits of management actions or the synergistic way in which the various combinations may act. We examine the value of Bayes Nets as a method for assessing the risk reduction from fire management practices using a case study from a forested landscape. Specifically, we consider the relative reduction in wildfire risk from investing in prescribed burning, initial or rapid attack and suppression. The Bayes Net was developed using existing datasets, a process model and expert opinion. We compared the results of the models with the recorded fire data for an 11-year period from 1997 to 2000 with the model successfully duplicating these data. Initial attack and suppression effort had the greatest effect on the distribution of the fire sizes for a season. Bayes Nets provide a holistic model for considering the effect of multiple fire management methods on the risk of wildfires. The methods could be further advanced by including the costs of management and conducting a formal decision analysis. © IAWF 2011.

Penman T.D.,Forest and Rangeland Ecosystems | Penman T.D.,Bushfire Co operative Research Center | Binns D.L.,Forests NSW | Shiels R.J.,Forest and Rangeland Ecosystems | And 3 more authors.
Austral Ecology | Year: 2011

Forest management practices have the potential to impact upon native vegetation. Most studies focus on the effects of management on the above-ground vegetation communities, with little attention given to the soil stored seed bank. Here we examine the soil stored seed bank of a long-term experimental site in south-eastern Australia, which has experienced timber harvesting and repeated prescribed burning over a 20-year period. At each of 213 long-term vegetation measurement plots, 3.5kg of soil was collected and germinated in a glasshouse over a period of 2years. Comparisons were made between the experimental treatments considering differences in species richness, abundance and community composition of the understorey seed bank. Logged sites had a higher diversity and abundance of seedlings compared with unlogged sites, which is consistent with observed changes in standing vegetation within 10years following logging. Prescribed burning resulted in a lower diversity and abundance of seedlings, which contrasts with the increase in species diversity observed in response to frequent fire in standing vegetation. Individual taxa that declined in the seed bank in response to frequent fire were all taxa for which germination is enhanced by exposure to smoke. Contrary to expectations, these did not exhibit a corresponding decline as standing plants. While management actions above ground are having minor impacts, greater effects were seen in the soil stored seed bank. © 2010 The Authors. Journal compilation © 2010 Ecological Society of Australia.

Penman T.D.,Forest and Rangeland Ecosystems | Penman T.D.,Bushfire Cooperative Research Center | York A.,University of Melbourne | York A.,Bushfire Cooperative Research Center
Forest Ecology and Management | Year: 2010

Predicted changes to global climates are expected to affect natural fire regimes. Many studies suggest that the impact of these effects could be minimised by reducing fuel loads through prescribed burning. Fuel loads are dynamic and are affected by a range of factors including fire and climate. In this study, we use a 22-year dataset to examine the relative influence of climate and fire history on rates of litterfall and decomposition, and hence fuel loads, in a coastal Eucalypt forest in south-eastern Australia. Litterfall and decomposition were both affected by temperature, recent rainfall and fire history variables. Over the study period prescribed burning immediately reduced fuel loads, with fuel loads reaching pre-burn levels within 3 years of a fire. Modelling fuel loads under predicted climate change scenarios for 2070 suggests that while fuel loads are reduced, the levels are not significantly lower than those recorded in the study. Based on these predictions it is unlikely that the role or value of prescribed burning in these forests will change under the scenarios tested in this study. © 2010.

Fischer J.,Australian National University | Stott J.,Australian National University | Law B.S.,Forest and Rangeland Ecosystems
Biological Conservation | Year: 2010

Scattered trees are declining in agricultural landscapes worldwide. They are considered keystone structures because their effect on ecosystem functioning is believed to be disproportionate relative to the small area occupied by any individual tree. We empirically demonstrate the disproportionate value of scattered trees for birds and bats in an Australian livestock grazing landscape. We surveyed birds at 108 sites and bats at 63 sites. Sites spanned the full range of tree densities in the study area, from zero to over 100 trees per hectare. The marginal value of individual trees was highest when trees occurred at low densities. Compared to treeless sites, bird richness doubled with the presence of the first tree; bat richness tripled with the presence of 3-5 trees; and bat activity increased by a factor of 100 with the presence of 3-5 trees. Thereafter, the marginal effect of additional trees on birds and bats diminished rapidly. Although specialist species were restricted to large areas of dense tree cover, scattered trees effectively maintained moderate levels of bird and bat activity throughout largely cleared parts of the landscape. Future management activities should recognize the disproportionate value of scattered trees. © 2010 Elsevier Ltd.

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