Nedlands, Australia
Nedlands, Australia

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Milne A.E.,Rothamsted Research | Haskard K.A.,Data Analysis Australia Pty Ltd | Webster C.P.,Rothamsted Research | Truan I.A.,Rothamsted Research | And 2 more authors.
Journal of Environmental Quality | Year: 2013

We analyzed data on nitrous oxide emissions and on soil properties that were collected on a 7.5-km transect across an agricultural landscape in eastern England using the discrete wavelet packet transform. We identified a wavelet packet "best basis" for the emission data. Wavelet packet basis functions are used to decompose the data into a set of coefficients that represent the variation in the data at different spatial frequencies and locations. The "best basis" for a set of data is adapted to the variability in the data by ensuring that the spatial resolution of local features is good at those spatial frequencies where variation is particularly intermittent. The best basis was shown to be adapted to represent such intermittent variation, most markedly at wavelengths of 100 m or less. Variation at these wavelengths was shown to be correlated particularly with chemical properties of the soil, such as nitrate content. Variation at larger wavelengths showed less evidence of intermittency and was found to be correlated with soil chemical and physical constraints on emission rates. In addition to frequency-dependent intermittent variation, it was found that the variance of emission rates at some wavelengths changed at particular locations along the transect. One factor causing this appeared to be contrasts in parent material. The complex variation in emission rates identified by these analyses has implications for how emission rates are estimated ©American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America.

Manning R.,Western Australian Department of Agriculture and Food | Sakai H.,Data Analysis Australia Pty Ltd | Eaton L.,Data Analysis Australia Pty Ltd
Australian Journal of Entomology | Year: 2010

Langstroth hives fitted with a modified lid with an entrance lined with soft felt or steel or plastic pollen traps or hives fitted with plastic pollen traps and sugar-fed significantly increased the pollen count on the bodies of exiting honey bees. In terms of utilising the research findings in contract pollination service where costs can determine profitability, the recommendation is for a trial in a commercial orchard (e.g. almond, apple, avocado, plum) of sugar-fed single hives fitted with plastic pollen traps. Despite the bees' destruction of the felts lining the modified lid entrances, the soft felt liner might be a worthwhile inclusion into any field trial. © 2010 The Authors. Journal compilation © 2010 Australian Entomological Society.

Whitford K.R.,Science Division | Stoneman G.,Sustainable Forest Management Division | Seymour A.,Forest Products Commission | Murray P.,Forest Management Branch | And 2 more authors.
Australian Forestry | Year: 2012

Timber harvesting with heavy machinery can cause long-lasting compaction of forest soils, adversely affecting soil processes such as infiltration and respiration that are fundamental to forest health. This study examined the effectiveness of corduroying as a means of reducing soil compaction on log extraction tracks during timber harvesting under moist soil conditions in the forests of south-western Western Australia. The effects of the weight of logs removed from the stand, soil gravel content and initial bulk density, were also considered. Timber harvesting under moist soil conditions lead to significant compaction of surface soil on primary and secondary extraction tracks. This compaction was significantly related to four factors: timber load, initial soil bulk density and gravel content, and the use of cording. Compaction increased as the total load of timber hauled over the tracks increased. Soils with a high initial bulk density were less compacted during timber harvesting than soils with a low initial bulk density. On soils with initial bulk densities greater than about 0.55 g cm-3, compaction decreased as gravel content of the soil increased. Cording also significantly reduced soil compaction, but this reduction was small and may not justify the cost or the associated negative environmental impacts of routinely using corduroying while harvesting timber on moist soil. While reducing the load of timber hauled over an extraction track reduces soil compaction, this does not provide a practical solution for reducing soil damage in timber harvesting. Rather than dispersing traffic across many extraction tracks to reduce the load on individual tracks, the impact of soil compaction is best minimised by focusing all traffic onto as few tracks as possible; thus minimising the area of forest soil that is compacted by harvesting machinery. In addition, reusing compacted extraction tracks that remain from any previous harvesting is one of the most effective means of reducing the impact of timber harvesting on forest soils.

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