Consequences of broadscale timber plantations for biodiversity in cleared forest landscapes of tropical and subtropical Australia

Background

In Australia, as in many countries, there has been a shift in timber production from native forests to plantations. While plantations are primarily considered an efficient means of producing timber, there is increasing interest in their potential contribution to biodiversity conservation. This paper conducts a literature review of the impacts of plantations on biodiversity and assesses plantation scenarios proposed for cleared rainforest landscapes in tropical and subtropical Australia.

Research and methods

The scenarios under consideration in Australia include monocultures of hoop pine, exotic pine, or eucalypts; mixed species plantations; mosaics of monoculture plantations; and mosaics of plantations and ecological restoration plantings.

Of these scenarios, plantations of eucalypts and exotic pines have the least positive consequences for biodiversity. The three scenarios based on plantations of rainforest trees have similar, moderately positive consequences for biodiversity, while a mosaic of plantations and restoration plantings has the most positive consequences for biodiversity in cleared rainforest landscapes.  All scenarios may have negative impacts on biodiversity conservation if plantations replace remnant forest or if exotics used in plantations spread to native forests.

Conclusions and takeaways

In practice, the ranking of scenarios may vary with landscape forest cover. Scenarios with strongly potentially positive consequences for biodiversity would be favored for the reforestation of heavily cleared landscapes, whereas scenarios with fewer potentially negative consequences for biodiversity would be favored in well-forested landscapes. The study recommends further research on long-term biodiversity and timber dynamics on a landscape scale in large plantation projects.