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Meeting Notes - March 24th

Meeting with Associate Professor Brian Finlayson 16/3/01 Centre for environmental applied hydrology School of anthropology and applied environmental studies The Melbourne University Margy Dockray (Mt. Arthur Environment Management Group) and Frank Strie (Private Forestry Consultant) met with Prof. Brian Finlayson from 9.30am to 6.00pm on site at coupe LI 126C on Mt. Arthur on Friday 16th March. We were joined by Jonno Pedley (Mt Arthur Environment Management Group) for some of this time. The purpose of Brian's visit was to outline the likely impacts from an hydrological point of view regarding the consequences of clearfelling/plantation establishment across the coupe, as well as in areas adjacent to the coupe. We took Brian to several sites within the coupe, including the variation, where he examined logging practices, definition of streams and reserves, roading, drainage, geological form and soil types. From these observations, he drew the following conclusions. The effects of clearing native forest and replacing with plantation: Water Yield Relevant Data: The scale of the clearing and replacement plantations in this area is so large that the effects on the water yield have the potential to be tremendous. This extensive clearing has been conducted without sufficient data and study, ie no small scale pilot areas established and monitored for changes in water yield. Therefore, any conclusions drawn, (including those Forestry Tasmania, and Brian Finlayson) as to the effects on water yield, of such large scale plantation establishment, could only be speculation. Given the nature of the operation, (clearing of forest which has taken millennia to establish) any impact on water yield will be long term and one way (as good as irreversible). Therefore, Brian suggested that the continued clearing and replacement with plantation is both foolish and dangerous, as the effects on water yield although unknown, could be catastrophic. He described the operation as "flying blind" in relation to water yield. Brian based his conclusions on data available through smaller scale clearing of areas of Eucalyptus Regnans forest in central Victoria, which has both similarities and differences to the area on Mt. Arthur. On the basis of extrapolation of data from these studies, Brian guesses that there will be a reduction in water yield. Brian stressed that although others may form different conclusions, their conclusions would not be based on alternative evidence. There just is no data on which to make reliable conclusions. Water Quality The effect on water quality by clearing and plantation establishment in this operation will take two forms - impact from run-off (carrying sediment thereby increasing turbidity) and impact from use of chemicals and sprayed herbicides. RunOff. Preamble: Unidentified streams Throughout the coupe and surrounding areas, there was evidence that streams and water carrying depressions had been ignored and disturbed. This was particularly noticeable in the area known as the variation to the FPP for Coupe LI 126C. In the section above the Mt. Arthur Road, at least 4 streams, currently flowing (after prolonged dry period) were identified. According to the FPC 2000, these streams were at least class 4, and probably even class 3 (for definition, see p56). That they existed should have been evident by the vegetation, which was rainforest, with no eucalypti. Two of these streams, although running, are not defined by significant depressions, and could not have been noted through contours in aerial survey, although the other two were defined by depression. The variation to the FPP made no mention of any of these streams, indicating that the hydrological survey was inadequate in assessment for the coupe. The operator had therefore cleared the entire area, with major disturbance to the streams. Still in the variation, in the area below the Mt. Arthur Road, depressions were noted, having been entirely cleared, and used as snig tracks for the removal of logs. These depressions were identified as class 4 streams, leading directly into the class 3 stream marked as being at the head of the Shepherd's Rivulet, on the edge of the coupe. Insufficient Buffer Zones in streamside reserves. Throughout the coupe, streams identified on the FPP were not afforded appropriate exclusion zones. The nature of these streams high in the catchment is that they cover a broad area, with ill-defined banks and boundaries. Again, the boundaries of the streams can be ascertained through studying the vegetation. Stream boundaries change according to the seasonal conditions. As the soils become saturated during wet periods, the water table rises and the boundaries of the water courses expand and widen. In some cases the stream itself grows in width from a narrow channel to 20 or 30 meters wide. (For example, the stream on lower side of road before the intersection to Lone Star Road). According to the FPC 2000, streams will be afforded exclusion zones according to their classification, which extend from both edges or banks of the stream as it runs during the wettest periods. It is these non-disturbed exclusion zones which are supposed to absorb any sediment caught up in the run-off, before it reaches the stream system itself. In the coupe however, exclusion zones were inadequate, being measured from the middle of the streams assessed in the dryest season rather than from their extremities in the wettest conditions. Roading, and provision of drains for run-off. The Mt. Arthur Road was not adequately constructed, being flat, with no table drains. Existing culverts had been damaged and/or covered. According to the code, all forestry roads must be shaped and table drains constructed, with frequent exits for dispersement of water into areas of undisturbed vegetation, where most of the sediment from the run-off from disturbed areas could be trapped and collected. There were insufficient exits, and undisturbed patches of vegetation, to enable adequate protection for streams. Instead, all run-off water would be expected to build up on road edges, collecting at the lowest points (where there were depressions and streams), and flow directly into the stream systems. In conclusion: Much of the disturbed soil and rock, would be picked up and washed into the streams, causing ongoing sedimentation and increased turbidity. This has two effects. Firstly, the water becomes contaminated with silt, requiring filtering for human consumption downstream, and secondly, a fine layer of sediment is deposited over stream bed, causing a blanketing of habitat for macro-invertebrates, at the bottom of the food chain, which then affects the whole eco-system. Also, the vegetation in these areas is sensitive and largely intolerant to the build up of sediment around their roots and buts. Chemical contamination Preamble: The argument that the spraying of herbicides, application of fertilisers and laying of 1080 poison, is of no environmental concern, lies in the assertion that these rainforest soils have a thick humus layer, which acts as a filter to chemical contaminants. The surface water containing contaminants gradually percolates down through this thick humus layer into the soil where the chemicals are fully absorbed and bio-degraded. Thus, the soil filters out all contaminants before the water reaches the water table where it is transported clean, into the streams and river systems. Brian explained that while there is some truth in this argument, it was not true in soils that had been subject to ground preparation prior to plantation establishment because once the forest had been cleared, the thick humus layer is dissipated through burning and ploughing. Also in these forest soils, there are "macro pores" (root holes, structural cracks, animal burrows etc.) where some of the surface water is transported directly down, straight through into the water table, with no opportunity for contaminants in this proportion of water to be absorbed. This is further complicated in areas of block fields such as the higher parts of Mt Arthur (deep cavities carrying water laterally through conduits below the surface) which transport these contaminants downstream. So you have a proportion of contaminants being moved quickly down through the soil in macro pores then laterally through soil through block fields emerging in springs and streams lower down the slope. These contaminants all then pass into the food chain. Diesel contamination: Diesel and oil will travel through the soil. Where there have been small spillages, as has happened on the coupe, the worry is that the operators are carrying out practices that are unsafe, and may lead to catastophe. Conclusions: Contamination of the water table, with chemicals from herbicide and fertiliser application associated with plantation establishment will result from the operations in the area. Contamination of surface water from run-off, and soil erosion, will occur, increasing particularly as the soil becomes saturated during prolonged wet peroiods. This surface water will find its way into streams and rivers because of inadequate buffer zones of undisturbed vegetation. The impact of this is likely to be to cause damage to the ecosystems of the rivers and streams through siltation, as well as increased turbidity in water downstream. Specific for water catchment areas: The higher up the mountain you go, the greater the water yield because of increasing rainfall, and lowering of transpiration due to decreasing temperatures. This means that the higher up the mountain, the more fragile and sensitive the area. According to the code, no more than 5% of a town water supply catchment can be felled each year. The reason being the risk of contaminants to the water supply. The problem with the code as it stands is that it only mentions town water catchment. Those outside the towns who are also adversely affected by contaminants in the water are not afforded the same consideration and protection. Problems with using maps for assessment of coupe's water courses: Often contours on a map will show a depression but not a stream (blue line). In very wet conditions, the streams extend uphill. The water is carried down the depressions which would be completely dry at this time of year. Also, the contour lines on maps themselves are not necessarily accurate. Most contours are mapped from aerial photographs, which do not show very small depressions, or streams which run without a depression or topographical definition, as is the case high up in this catchment. Also, the forest canopy is uneven and irregular, therefore it often hides these types of water courses. Even walking over the ground may not show up water courses, as they may be covered over with large quantities of rotting vegetation and leaf litter. Provision is made within the FPP that if one of these streams is discovered by an operator, he must then contact a Forestry Tasmania officer. The problem with this is that the operator may only discover the stream when it is already too late, having disturbed it with felling and machinery. Preparation of the land for planting and the deep ripping of the slopes: The ripping of rows up and down the slopes acts as tiny class 4 water courses, pulling sediment off the slopes directly into the streams and rivers and contributing significantly to soil erosion. This practice was noticed in areas adjacent to the coupe.

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