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Seeking a balance between forestry and biodiversity – the role of variable retention silviculture. Insights from western USA and Canada.
Baker, SC (2011) Seeking a balance between forestry and biodiversity – the role of variable retention silviculture. Insights from western USA and Canada. Project Report. FWPA, Melbourne.
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achieve improved biodiversity and social outcomes compared to clearcutting and other
traditional silvicultural systems. VR was initially developed in the Pacific Northwest (PNW)
of USA and Canada, where it is applied in a broad variety of forest types, ages and land
tenures. VR has recently been implemented in wet old-growth forests in Tasmania, and there
is scope for broader implementation in both Tasmania and mainland Australia. Hence,
insights from the PNW about operational experience, research, adaptive management, and
efforts to improve relationships between timber industry and environmental groups are of
broad relevance to forest management in Australia.
This report covers three main topics. Chapter 2 presents the results from surveys of twelve
organizations that are currently implementing VR across western USA and Canada. These
surveys explored motivations for using VR, variation in implementation, adaptive
management and monitoring, and perceived success of the system. Chapter 3 of the report
discusses research and formalized adaptive management programs relating to improving
conservation outcomes from silvicultural practices. This includes descriptions of some of the
large silvicultural trials investigating biodiversity and silvicultural outcomes of VR and
clearcutting. Two emerging areas of research are discussed: the importance of early-seral
forests for biodiversity, and the role of ‘forest influence’ in facilitating recolonisation of
harvested areas by biodiversity from nearby mature forest. Chapter 4 provides examples of
successful collaborations that have settled long-term conflicts between timber industry and
environmental groups, resulting in improved conservation outcomes and continued timber
The development and implementation of VR in the PNW has been an excellent example of
adaptive management. Although the desire for improved social acceptability was often a
primary driver for using VR along with the desire for improved ecological outcomes,
organizations clearly embraced the ecological objectives of the system. There was a lot of
variability in VR implementation across the region. The system was used in a wide variety of
forest types, including old-growth, second and third-growth forests; and a variety of land
tenures including those managed by industrial companies on both public and private lands,
State governments, small private ownerships and First Nations people.
Most organizations used one or more of the three main harvesting patterns: aggregated
retention where uncut forest is left in groups, dispersed retention where scattered trees are
retained, and mixed retention which combines the previous two approaches at the one site.
Aggregated retention and mixed retention were most widely used. This related to a
combination of operational, social and ecological factors. Research trials are showing that
aggregates are able to maintain a broader variety of species than are dispersed trees, although
some species are advantaged by the more uniform distribution of trees with dispersed
retention. Windthrow monitoring has shown that with the exception of some wind-firm
species, windthrow is reduced with aggregated retention. Large aggregates are less prone to
windthrow than small ones. Organizations using VR were adapting their practices in response
to operational experience and the results of research and monitoring. Those organizations with
direct links to research trials appeared to be making the most informed changes. Good training
programs, strong leadership and organizational cultures supportive of ecologically sustainable
forestry practices were important to success. Using VR had generally achieved the social and
ecological objectives, and organizations were planning on continued implementation.
However there was uncertainty over long-term ecological outcomes, emphasising the need for
long-term biodiversity research.
|Item Type:||Report (Project Report)|
PROJECT NUMBER: PGD167-0910
|Date Deposited:||26 Aug 2011 02:21|
|Last Modified:||26 Aug 2013 23:42|
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