Reforestation for biodiversity recovery: opportunities and limitations

Abstract

Deforestation clearly leads to a loss in biodiversity. However, the pathways of potential recovery that could follow the reforestation of cleared land are not so obvious. In heavily-cleared regions, the limited area of the few remaining native forest fragments is often insufficient to maintain species and processes, and a return of forest cover over a larger proportion of the land is needed to restore or maintain biodiversity to the landscape. The many options for reinstating forest cover range from tree plantations to voluntary oldfield regrowth. A wide range of plantation styles is also possible, and in the past the preferred form of design and management has often been driven by the goal of maximising production, coupled with a tradition of monospecies planting. Whether or not the process of reforestation is accompanied by a restoration of biological diversity will depend on a number of factors, at both site and landscape levels. These include tree species selection, plant functional variety, complexity of physical vegetation structure, configuration and spatial complexity of the planted area, harvest regimes, size of a forest patch, and nature of adjacent and surrounding land cover/land use. Furthermore, important effects of reforestation on biodiversity may occur on-site or off-site. We review these issues and illustrate selectively with information from case studies. While current knowledge enables recommendations and predictions to be formulated, there is also a need to obtain real-world performance data from a greater range of plantation designs. This requires their establishment at suitable spatial scales, together with quantitative long-term assessment of biodiversity indicators. Biodiversity is here defined as the variety of indigenous species (including flora, fauna, and microbes) and ecological processes.