Webb A.A.,Forests NSW |
Kathuria A.,Forest Science Center
Journal of Hydrology | Year: 2012
Competition for water resources in Australia's Murray Darling Basin has resulted in plans to account for water used by various land use change activities including plantation forests. To date generalised forest conversion models have been used to assess the likely impacts of future afforestation. These models are a useful starting point but do not account for forest age or silvicultural intervention such as thinning. A twenty year record from the Red Hill paired catchment study was analysed to show that forest age is a significant factor in determining the streamflow response to afforestation. Compared to the Kileys Run pasture catchment, streamflow in the Red Hill catchment afforested with Pinus radiata plantations steadily declined, particularly after age 6. years when stand basal area rapidly increased. Mixed effect model analysis indicated that over the first 20. years of the rotation the mean annual impact of afforestation with pines was 155. mm. The modelled impact peaked at 211. mm in year 14 prior to thinning. Thinning at age 14. years had a significant positive effect on streamflow that has persisted for at least 6. years. Drought conditions coupled with a process of recharging the catchment soils contributed to a delayed response to thinning. Factors such as forest age and thinning should be incorporated into models used in water resources planning to more accurately predict the hydrological effects of afforestation. © 2011 .
Webb A.A.,Forests NSW
IAHS-AISH Publication | Year: 2012
In New South Wales (NSW), Australia, local combinations of sclerophyllous vegetation dominated by Eucalyptus species, rapid fuel accumulation, terrain and weather can result in a high probability of uncontrollable wildfires. For example, in December 2001 and January 2002 the "Black Christmas" bushfires burned 733 342 ha of forest, including 225 000 ha within the Sydney water supply catchments. Evidence from several studies in NSW indicates that the effects of wildfires pose an unacceptable risk to water supplies. A parliamentary inquiry into the Sydney fires has resulted in a greater focus on hazard reduction. As forests in NSW occur on a mixture of land tenures, legal, institutional and economic barriers limit the effectiveness of efforts to reduce wildfire risk. This paper introduces the concept of payments for ecosystem services (PES) and discusses successful schemes that have recently been implemented to reduce the risk of wildfires in catchments supplying water to the cities of Santa Fe, New Mexico and Denver, Colorado in the USA. © IAHS Press 2012.
Jurskis V.,Forests NSW
Forest Ecology and Management | Year: 2011
Fallen timber is widely considered to be a key element of ecosystem structure and function that is critical to maintenance of biodiversity. This concept is closely linked to ideas of wilderness and old growth. 'Conventional wisdom' is that fallen timber has been drastically depleted from natural levels by human activity. However natural conditions reflect interactions of Aborigines with their environment, and fallen timber as well as broadcast fire was critically important to Aboriginal economies in the New World and Australia. Quantitative historical data are not available, so it is necessary to use qualitative historical information to describe natural loads and dynamics of fallen timber. A comparison against detailed historical descriptions of woodlands under Aboriginal management in Australia indicates that benchmarks from 'undisturbed' examples of the same types of vegetation are generally inflated. The ecological history of grassy woodlands since European settlement shows that proposed 'restoration' measures will favour common and widespread biota at the expense of rare and endangered species. No correlation of biodiversity with fallen timber has been demonstrated for grassy eucalypt ecosystems. Globally, conservation strategies that minimize human activity have generally failed because resilience of ecosystems and ancient trees has been reduced and rare species have been lost. The concept of wilderness has little application outside the unpeopled continent of Antarctica. © 2011 Elsevier B.V.
Webb A.A.,Forests NSW |
Dragovich D.,University of Sydney |
Jamshidi R.,University of Sydney
Forest Ecology and Management | Year: 2012
Unmitigated forestry operations have the potential to impact upon suspended sediment yields within headwater catchments. Best Management Practices (BMPs) are therefore required to reduce the effects on downstream users and to protect the integrity of aquatic ecosystems. Accordingly, in New South Wales, Australia, harvesting and roading activities on multiple use State forests must comply with Environment Protection Licences (EPLs) that require BMPs to be used to protect the aquatic environment from water pollution. The BMPs include soil conservation measures for the design of bridges, culverts and causeways; appropriate drainage spacings on roads and skid trails; seasonal harvesting restrictions; slope restrictions for harvesting and road construction activities; wet weather restrictions on the use of roads and log landings; and protection of all drainage features, including zero order streams, by the use of filter strips and/or buffer strips from where harvesting is excluded.In this study, conducted between 2001 and 2009 in Kangaroo River State forest, a replicated paired catchment experimental design was utilised to assess the effects of forestry activities on suspended sediment yields within three catchments selectively harvested using EPL-compliant BMPs. We hypothesised that harvesting within three treated catchments would increase suspended sediment yields but that the BMPs would reduce the magnitude and persistence of any measured effects. Harvesting during 2007 resulted in an increase in streamflow equivalent to 25.2mmy -1 to 46.4mmy -1 for each 10% of the area harvested in two of the three treated catchments, which is consistent with previous studies worldwide. Mean monthly concentrations of suspended sediment did not change following harvesting; however, the suspended sediment yield of one catchment, I-3, was significantly increased by 25.2% in the immediate post-harvest period. The overall suspended sediment yields remained low with monthly yields ranging from 0kgha -1 during cease-to-flow conditions in all catchments to a high of 116.1kgha -1 during February 2009 in the I-2 catchment. The measured increase in suspended sediment yield due to selective harvesting in the I-3 catchment was limited to a few post-harvest flow events and had subsided within 12months of the cessation of harvesting. The BMPs utilised during the harvesting operations, the ridge-top location of roads and log landings, and the high degree of groundcover retained on skid trails and the General Harvest Area in the absence of a regeneration burn contributed to the minimal impacts measured during this study. © 2012 Elsevier B.V..
Jurskis F.V.,Forests NSW |
Underwood R.,PO Box 262
Australian Forestry | Year: 2012
We agree with von Platen et al. (2011 ) that an understanding of fire history is important in considering fire regimes for conservation. However, their contribution indicates a lack of understanding of the history of Aboriginal fire management in Australia and the relationships amongst the frequency of fire, the severity of fire and vegetation structure. Though they purported to test fire scar dendrochronology against the historical fire record, they actually tested it against the record of years with 'bad' or 'widespread' fires. There was no test of the probability of fire scarring in relation to fire severity. Their discussion of land management history was superficial, and Aboriginal management was not described. The fire regime reported by these authors for the period of Aboriginal management is clearly at odds with historical records.