Landscape-scale dynamics and restoration of dryland forest ecosystems
Authors: Newton, A. et al.
Publisher: International Union for Conservation of Nature
Place of Publication: Gland, Switzerland
The restoration of forest landscapes is typically achieved either through passive restoration, involving the establishment of forest cover through natural regeneration, or some form of active restoration approach, involving the establishment of trees by artificial means. The existence of different restoration options raises the question of how an appropriate restoration approach might best be identified for any individual location. Where feasible, passive restoration approaches are often likely to be preferred, because of the intrinsically lower costs of tree establishment. However, the potential for natural regeneration of forest cover may often be limited, particularly in landscapes that are highly degraded. Factors that can limit the process of natural regeneration include a lack of a source of propagules, perhaps because an individual site is isolated from remnant forest stands; adverse site characteristics for seed germination or seedling establishment, such as degraded or compacted soils; or an adverse disturbance regime that causes high mortality of juvenile trees. In areas where passive restoration approaches are associated with a high risk of failure, active restoration approaches may be preferred.
The results presented here highlight the value of spatially explicit modelling tools for exploring the potential for restoration of forest landscapes. Specifically, the modelling approach used (LANDIS II) enabled projections to be made regarding the pattern of regeneration and spread of native forest under different anthropogenic disturbance regimes, providing an insight into the potential for passive restoration approaches. The model also highlighted interactions between different forms of disturbance and their impacts on restoration processes, an area in which information is currently lacking. For example, modelling scenarios conducted in Chile indicated how spread of the invasive exotic species Acacia dealbata is dependent on other forms of disturbance such as grazing and fire. These examples demonstrate how spatial models can inform approaches to forest landscape restoration, by indicating those locations within a landscape where particular restoration approaches are most likely to be successful. In addition, spatially explicit modelling tools provide a means of visualising the potential impact of restoration actions at the scale of entire landscapes.