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Project summary:
The silvicultural systems trial (SST) is investigating alternative silvicultural systems for the management of wet eucalypt forests for wood production. This component of the trial, involving birds, aims to characterise and compare bird assemblage structure and diversity in treatment and control areas, and monitor their successional pathways following disturbance after a range of silvicultural treatments.
Within each coupe and control, monitoring sites have been established approximately in the ratio of one per two hectares. Five-minute point counts are then undertaken 8-10 times each spring (September to December) at varying times of the day over a number of visits. For details of the methodology see WRA104.
The pre-logging surveys were carried out by two observers: Andrew Hingston and Bill Brown both in 1998 using both line and point counts. These surveys all form baseline data for comparison with post-logging data. All the post-logging surveys have been carried out by Paul Lefort each year from 2004 and 2007. These data should provide valuable information concerning the effects of different logging systems on bird communities.
There are currently (2008) 61 species on the Warra bird list. However, 17 of these species are either vagrants or rarely detected in the area.
These are the other bird projects undertaken at Warra:
WRA034 Birds and wet eucalypt forest succession.WRA068 Bird monitoring along an altitudinal transect on Mount Weld.WRA104 Development and implementation of standardised bird surveys in wet eucalypt forest at Warra.Download a pdf (788kb) of a PowerPoint presentation given at the Old Forests New Management Conference in Hobart in February 2008
Methodology: The protocol for point counts developed at Warra is as follows. Permanent survey points were established within each study coupe at a rate of about one per hectare. While random locations would have been preferable, this was impracticable given the difficulty of moving through the dense forest at Warra. Instead, they were established along purpose-cut narrow pathways at least 50 m from a coupe edge to reduce the influence of edge effects. Edges within treatments (e.g. between the harvested and retained parts of STR) were, however, deliberately chosen as the location of some survey points. In such cases, whenever a bird was noted during a point count, its habitat (i.e. harvested area, edge or mature forest) was also recorded.
Birds were noted if within a radius of 25 m of the survey point. Choosing a wider radius would have reduced the accuracy of observations, especially when relying on bird-calls. In order to avoid any geographical overlap of sampling during a survey visit and hence double-counting, point centres were at least 50 m apart. Time overlap, in terms of birds moving undetected from one sample point to another and being recounted, was minimised by reducing each sample to five minutes (with a two minute pre-survey acclimation period on arrival at a new point). Other data collected were the bird’s height above ground, its approximate distance from the survey point, and its approximate bearing (helpful in later determining whether adjacent detections were of the same bird). The line transect surveys (which form the majority of the pre-logging surveys in 1998) were conducted such that axial distances of observations along the transects were recorded. This allowed these data to be split into 50 metre blocks approximately corresponding to 25 metre radius point circles. These data were then entered into the database as though from point surveys.
Bird identification to species level was mostly achieved based on calls alone (about 80% of all records).
Datasets: None available.
Publications: Forestry Tasmania (2009). A new silviculture for Tasmania’s public forests: a review of the variable retention program. Forestry Tasmania, Hobart.
Lefort, P. & Grove, S.J. (2009). Early responses of birds to clearfelling and its alternatives in lowland wet eucalypt forest in Tasmania, Australia. Forest Ecology and Management 258: 460-471.
Lefort, P. (2004). Bird monitoring at the Warra long-term ecological research site, Rep. No. 30/2004. Forestry Tasmania, Hobart.
Lefort, P. (2004). Bird surveys conducted at the Warra LTER site, 1998-2002, Rep. No. 31/2004. Forestry Tasmania, Hobart.
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