A landmark study has found that appropriately managed production forest landscapes have a similar biodiversity to that of largely undisturbed landscapes. The research, commissioned by Forest and Wood Products Australia and carried out by Forestry Tasmania and the University of Tasmania, has shown that tall eucalypt forests do not necessarily need to be in large reserves to provide suitable habitat for their associated animals and plants.
Rather, it is possible to effectively integrate the conservation of these species with wood production.
Researcher Dr Tim Wardlaw said the study had provided the scientific evidence to show that timber harvesting is compatible with the maintenance of biodiversity values – particularly when it is integrated with, rather than separate from, areas containing mature forests.
“There has been a shift of thinking in conservation science over the past decade. It’s now considered best practice to mix harvesting and retention across wider areas.
“The alternative – concentrating retention in large reserves and focusing harvesting in a smaller area outside those reserves – can create a tension between harvesting and biodiversity conservation outside the reserves.
“This study is one of the first to test this shift of thinking in conservation science.”
The study compared species abundance and diversity across a range of different forests, including:
· largely natural forests;
· forests that had been subject to intermediate levels of forestry harvesting and regeneration, such as those managed under the Regional Forest Agreement and Forest Practices Code; and
· forests that had been intensively disturbed by a history of more regular wildfires and harvesting pre-dating the RFA and Forest Practices Code.
“We found that disturbance-sensitive species persist in areas of retained mature forest, and recolonise harvested areas in those parts of the landscape that are managed at intermediate levels of forestry modification
“Significantly, the abundance and species-richness of these disturbance-sensitive species was comparable with levels found in largely natural landscapes reflective of large reserves.”
“However, in the parts of the landscape that had been subject to the most intensive levels of wildfire and harvesting, these disturbance-sensitive species were less able to recolonise harvested areas and some also had difficulty in persisting in the retained mature forest.”
Dr Wardlaw said one of the most important outcomes of the study was the strong scientific evidence it had provided to show how much mature forest should be retained in the landscape, and where it should be located, to ensure the most disturbance-sensitive species can persist.
“We hope these findings may contribute to a more informed public conversation about the way forestry and biodiversity are managed in the landscape. We can now be confident that informal reserves and set-asides – as well as the large reserves – have an important role to play.”
Dr Wardlaw said the study had been commissioned to evaluate the effectiveness of the Regional Forest Agreement in protecting the biodiversity of forest-dependent species.
“The intent of the RFA was to ensure biodiversity values were maintained across the entire landscape – not just in the large reserves.
“Because the RFA reserves are not distributed evenly across the landscape, off-reserve management is also key to maintaining biodiversity. However, the adequacy of this management has been questioned in recent times.
“For example, the Wielangta Federal Court case brought against Forestry Tasmania by former Senator Bob Brown some years back highlighted the contentious nature of this issue.”
Dr Wardlaw said the study sought to determine whether the smaller informal reserves, the set-asides required under the Forest Practices Code, and even production forests, made a contribution to maintaining biodiversity.
“We already knew that, under natural conditions, forests are a mosaic of older areas with younger areas created by wildfires. Forest-dependent species persist in the patches of unburnt older forest and provide a source to recolonise the burnt areas as they are regrowing after a wildfire.”
“We wanted to know whether this process also takes place within production forest landscapes.”
The study took place in the Southern Forests Experimental Forest Landscape (SFEFL), a 112,000-hectare research zone between the Huon Estuary and the World Heritage Area that Forestry Tasmania established in 2008. The SFEFL contains mainly tall wet eucalypt forest, but features a range of land management regimes ranging from agriculture, plantations and native forestry, through to relatively undisturbed forests.
“We set up research plots across this landscape – half in mature eucalypt forest and the other half in 30-50 year old forest regenerating after harvest – and surveyed them for birds, plants and beetles. The plots were carefully located to sample a gradient of disturbance intensity created by past wildfires and post-European land management.”
Dr Wardlaw will present the findings of the study at the Royal Society of Tasmania public seminar, Ecology, Forest Policy and Management, at the University of Tasmania Centenary Theatre TONIGHT, Tuesday 19 February at 7:30pm.