Shepherd M.,Southern Cross University of Australia |
Sexton T.R.,Southern Cross University of Australia |
Thomas D.,Forests NSW |
Henson M.,Forests NSW |
Henry R.J.,Southern Cross University of Australia
Canadian Journal of Forest Research | Year: 2010
Geographically distributed genetic variation is expected in species that have wide latitudinal and habitat ranges, like Eucalyptus pilularis Sm. Coastal and inland ecotypes of this tall forest tree have been distinguished in genecological studies, but patterns of regionally distributed quantitative variation are weak. At the coarsest level, variation of 12 micro-satellite markers divided a rangewide sample of 424 E. pilularis trees into two zones: the region to the south of Sydney forming one zone and regions to the north forming another. Genetic structuring did not correspond with ecotypes but rather with a biogeographic division, suggesting an imprint of historical isolation. Typical and uniform levels of genetic diversity (He = 0.78 ± 0.02 (mean ± SE)) were found across 10 geographic regions. Genetic structuring by regions (PhiRT = 3%), by localities within regions (PhiPT = 2%), between coastal and inland provenances (PhiPT = 2%), or due to isolation by distance was subtle. These observations, along with the lack of evidence for bottlenecks, suggested genetic cohesion within zones due to gene flow and historically large population sizes. The low levels of diversity and poor growth performance of the Fraser Island ecotype were better explained by recent colonization and adaptation than by genetic isolation, since there was no evidence of inbreeding.
Raymond C.A.,Southern Cross University of Australia |
Thomas D.S.,Forests NSW |
Henson M.,Forests NSW
Australian Forestry | Year: 2010
The economics of kraft pulping are influenced by variation in wood density and chemistry, or their product, pulp productivity. The ability to predict basic density, pulp yield or pulp productivity before harvest would provide an economic advantage to the grower or processor. Acoustic velocity in green wood is correlated with both basic density and pulp yield, offering potential for rapid screening. We explored relationships between acoustic velocity, density, pulp yield and fibre length using data from Eucalyptus dunnii plantations in northern NSW, Australia. Acoustic velocity measured on logs accounted for 27% of the variation in pulp yield and 50% of variation in pulp productivity. The strong relationship between fibre length and pulp yield is proposed as a possible causal mechanism. A threshold acoustic velocity of 3.65 km s -1 was defined as the point at which logs would produce at least 250 kg of dry pulp per cubic metre of green wood. Removal of the worst 25% of logs, based on velocity, would give a 2.2% gain in pulp productivity which equates, in turn, to an additional 6.2 kg of pulp produced from every cubic metre of green wood.
Webb A.A.,Forests NSW |
Webb A.A.,University of New England of Australia |
Kathuria A.,Australian Department of Primary Industries and Fisheries |
Turner L.,Forests NSW
Journal of Hydrology | Year: 2012
The Karuah replicated paired catchment experiment was initiated in the 1970s to examine the hydrological effects of eucalypt-to-eucalypt forest succession in New South Wales, Australia. Treatments were conducted on 25.4-78.8% of the area of six small catchments in 1983. Five of the treated catchments experienced a significant increase in streamflow following forest disturbance, equivalent to annual water yield changes ranging from 120mm to 319.6mm which varied in proportion to the percentage of each catchment logged. This initial increase lasted for greater than 5years in the logged and unburnt Bollygum (L-) catchment, but had returned to pre-treatment levels within 2.5years in the logged and burnt (L+) Corkwood and Jackwood catchments, and within 2years in the Kokata and Coachwood plantation catchments (P). A significant reduction in streamflow then occurred in three catchments - Corkwood (113.5mma -1), Bollygum (72.7mma -1) and Kokata (68.9mma -1) - but had returned to the pre-treatment level within 7years post-harvest in the Corkwood catchment. A continuing suppression of streamflow after 27years is evident in two of the catchments, Bollygum and Kokata, with Kokata experiencing a further decline from 2005 onwards to a mean annual reduction of 172.4mm. By contrast a significant increase in streamflow relative to the pre-treatment level has been recorded in the Jackwood catchment after 23years (157.6mma -1). Relative changes in streamflow measured in this experiment can be explained largely by changes in forest species composition, basal area and stocking rates. The eucalypt stands have variously self-thinned and in some cases forest growth appears to have been slowed by insect attack and bell miner associated dieback. Contrary to earlier published findings, while this study confirms that Mountain ash type water yield reductions can occur in other forest types, this response appears to be the exception rather than the rule. These findings have implications for the modelling and management of water yield impacts of mixed species eucalypt forest disturbance. © 2012 Elsevier B.V.
Doland Nichols J.,Southern Cross University of Australia |
Geoff R.,Forests NSW |
Smith B.,Forests NSW |
Grant J.,Southern Cross University of Australia |
Glencross K.,Southern Cross University of Australia
Australian Forestry | Year: 2010
The subtropical eucalypt plantation estate in eastern Australia has developed over several major periods of expansion and has now reached over 115000 ha. Before 1994 state agencies, particularly Forests NSW, had established about 20000 ha of mainly Eucalyptus pilularis and E. grandis on land previously under native forest in coastal areas with precipitation of more than 1000 mm y-1. Much of this area is now going into second-rotation plantations, mainly of E. pilularis. Since 1996, state government agencies have established large areas primarily for solid-wood products, and more recently private companies have established large areas for pulpwood as well as for solid wood. In any estate, several eucalypt species are usually required to fully use the available land due to the limitations imposed on individual species by frost, differing moisture regimes and complex soil landscapes. Species-site matching is further complicated by pest and disease problems in the major species that often are first evident where species are not ideally located. Several pest and disease problems have become evident only since the widespread planting of major species in plantations and were apparently present only at low levels in the native populations of these endemic species. Some subtropical species can produce trees having excellent wood properties, but the quality of timber from native forest trees and plantation-grown trees differs and much work remains to be done to define optimum rotation lengths and management regimes. Silvicultural and breeding strategies have been developed to improve performance in all the above respects.
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.
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.
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..
StClair P.,Forests NSW
Australian Forestry | Year: 2010
Trials were conducted to regenerate declining forests infested with lantana and psyllids near Mt Lindesay in northern New South Wales. Two years after treatment, trees in both controls and treated stands were significantly healthier. These changes were attributed mainly to drought-breaking rains. However, psyllid populations (as indicated by counts of bell miner, Martorina melanophrys) were higher in trees retained in treated areas than in control trees (in untreated areas), suggesting that treatments had not arrested chronic decline. Tree regeneration in treated areas was very variable and was dominated by brush box (Tristaniopsis confertus). Intense fire reduced lantana cover to a very low level in the year after treatment. Lantana cover doubled in the following year, but at 5% was still significantly less than before treatment (more than 80%). Declining eucalypt stands lack seed, and seedlings should be planted at high stockings (more than 1000 ha-1) to achieve canopy closure before lantana can recover to high levels. The cost of rehabilitating severely degraded stands, comprising 20% of the treated area, was AUD3500 ha-1. It appears unlikely that canopy closure will be achieved in the remainder of the treated area where recovery of shrubs and vines may make it difficult to reintroduce low-intensity fire. It is important to use low-intensity fire where possible to maintain essential ecological processes in dry to moist eucalypt forests so that they do not suffer canopy decline and shrub invasion.