The use of buffers on logging coupe boundaries which are referred to as ‘visual amenity strips’ by the forestry industry is nothing more than window dressing. Areas of remaining forest along the boundaries of clear-fell logging coupes exhibit particularly pronounced edge effects that over time extend further into the unlogged forest buffer zones. Ecological edge effects are defined as changes in population or community structures that occur at the boundary of two or more habitats.
If you look at the trees on the edge of a logging coupe after clear-felling and burning, they are often damaged by the high intensity fires. The trees on the edge of the forest are then subject to microclimate changes which lead to health decline and eventually death. The microclimate changes at the edge of the forest include an increase in solar radiation resulting in increased temperature, increased wind speed and a decrease in relative humidity. These changes contribute to an overall drying out of the forest edge which makes the area more prone to fire.
The logging industry uses clear felling and burning regimes that result in the loss of fern species such as tree ferns that help retain moisture in the forest. The high intensity burns destroy every living thing in their path and depletes the soil carbon levels and severely alters the soil biology. This exposed ground is then subject to increased solar radiation and erosion. Together with the roads that have been built for the logging, this produces a large amount of sediment entering into the waterways which negatively affects species such as the endangered giant freshwater lobster (Astacopsis gouldii) found only in the northern forests of Tasmania including the Blue Tier and Mutual Valley. The giant freshwater lobster is highly dependent on clean healthy waterways with cool temperatures and plenty of shade.
After clear felling and burning the forest the area is reseeded with a single species species of eucalypt, often stringy bark (Eucalyptus obliqua) or shining gum (Eucalyptus niten). Once the seeds germinate and the seedlings begin to grow into trees the area becomes a dense, even aged, oil rich regrowth wall of green that is impenetrable for decades and is highly flammable. This is a vastly different ecosystem from the old damp diverse forest that was there before logging.
It takes eucalypts around 150 years to form a mature canopy with tree hollows that 30% of our bird species are dependent on for nesting. The endangered wedge tailed eagle and masked owl generally select trees for nesting that are over 300 years old. With vast areas of old forest being clear felled, this is having a major impact on these endangered species now and in the future.
The Forest Practices Authorities (FPA) own data shows swamp gum (Eucalyptus regnans) forest, like those on the Krushkas trail, and Blue Tier are being over logged and are underrepresented in the reserve estate in north eastern Tasmania. Significant areas of this wet forest type have been clear felled and converted to different simple tree crops. With climate change increasing the frequency of wildfires, and the increasing loss of biodiversity we simply cannot afford to keep going with the status quo. The forests of the north east are worth more standing.