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Forest Restoration in Landscapes

Forest Restoration in Landscapes

34 J.

34 J. Biringer and L.J. Hansen provide nursery habitat for many fish species. Deteriorating water quality and coastal degradation are anticipated to be magnified by climate change. Globally, however, many mangrove systems have already been degraded and destroyed. Loss of these buffering systems precludes any protection they might afford. This has been recognised for some time, and many individual projects have attempted to rebuild mangrove systems. However, in the past, the emphasis of mangrove restoration projects has been on planting trees, and this has led to poor survival rates, such as in West Bengal, India, where survival rates in some projects were reported as low as less than 2 percent. 51 New approaches are therefore required. In addition, simply restoring a mangrove where it has been degraded will not necessarily be enough in the face of climate change. Restoration in an environment where the climate is rapidly changing will require taking into account a few additional elements as opposed to restoration in a stable context. Before starting a restoration programme, two additional steps are required: (1) assess the cause of mangrove loss and evaluate how to remove those causes if possible; and (2) take into account the added complexity relating to how climate change will affect the system: in this case primarily through sea-level rise. A large-scale mangrove restoration effort in Vietnam has demonstrated that this approach to mangrove management can benefit local resource users and enhance protection from storm surge and sea-level rise. 52 The restoration project in this region has planted more than 18,000 hectares of mangrove along 100 kilometres of coastline. In addition to creating a more stable coastline capable of surviving changing marine conditions, harvestable marine resources are also increasing in number. Understanding the hydrology (both frequency and duration of tidal flooding) is the single most important factor in designing successful mangrove restoration projects. 53 Incorporating projections of sea-level rise into project design will be necessary so that mangroves are planted or are allowed to colonise naturally or regenerate (this takes 15 to 30 years where stresses leading to degradation are no longer present) in areas that will be more hospitable in the future. If the shoreline is moving, for instance, mangroves may need to be restored some distance from their original location. 3. Outline of Tools This section offers a framework for integrating knowledge about climate change to forest managers who are considering restoration. It is based on an understanding of how adaptation (in this case to climate change) needs to be integrated with both restoration and protection, as outlined in Box 5.1 above. 3.1 Vulnerability Analysis To understand how climate change will affect an existing forest system, an analysis of the vulnerability of the defined area can be undertaken.As a first stop, climate change impacts on the major forest types are presented in WWF’s Buying Time: A User’s Manual for Building Resistance and Resilience to Climate Change in Natural Systems, 54 with examples from many different regions collected from the literature. For more specific information on a particular site, a literature search may identify whether a vulnerability analysis has been made of the project area in question. If limited information on climate change impacts exists for the selected site, a vulnerability analysis can be commissioned to feed into project design activities. An expert conversant in climate change science as well as biological science for the region can piece together a picture of regional vulnerability that will help to guide project activities so that they can take account of likely alterations in environmental conditions as the climate changes. At a large 51 Sanyal, 1998. 52 Tri et al, 1998. 53 Lewis and Streever, 2000. 54 Hansen et al, 2003 (available on www.panda.org).

scale, major shifts in biome types can be projected by combining biogeography models such as the Holdridge Life Zone Classification Model with general circulation models (GCMs) that project changes under a doubled CO2 scenario. Biogeochemistry models simulate the gain, loss, and internal cycling of carbon, nutrients, and water-impact of changes in temperature, precipitation, soil moisture, and other climatic factors that give clues to ecosystem productivity. Dynamic global vegetation models integrate biogeochemical processes with dynamic changes in vegetation composition and distribution. Studies on particular species comparing present trends with paleoecological data also provide indications for how species will adapt to climate change. 55 A vulnerability analysis can help to assess what systems or aspects of the systems have greater resilience and resistance to climate change impacts. This type of information can help to identify sites that have greater longterm potential as ecosystem “refugia” from climate change impacts. Some refugia exist due to their unique situational characteristics, but their resilience could be enhanced by management and restoration. 3.2 Restoration as a Resilience/ Adaptation Strategy After completing a vulnerability analysis to determine how a forest system may be impacted by changing climatic conditions, the next step is to look at the range of adaptation options available in order to promote resilience. An effective vulnerability analysis will determine which components of the system— species or functions, for example—will be most vulnerable to change, together with consideration of which parts of the system are crucial for ecosystem health.An array of options pertinent to adapting forests to climate change are available, both to apply to forest communities at high risk from climate change impacts as well as for those whose protection should be prioritised given existing resilience. Long-term 55 Hansen et al, 2001. 5. Restoring Forest Landscapes in the Face of Climate Change 35 resilience of species will be enabled where natural adaptation processes such as migration, selection, and change in structure are allowed to take place due to sufficient connectivity and habitat size within the landscape. Restoration can provide a series of critical interventions to reduce climate change impacts. 56 Basic tenets of restoration for adaptation include working on a larger scale to increase the amount of available options for ecosystems, inclusion of corridors for connectivity between sites, inclusion of buffers, and provision of heterogeneity within the restoration approach. Key approaches are as follows: Reduce fragmentation and provide connectivity: Noss57 provides an overview of the negative effects of ecosystem fragmentation, which are abundantly documented worldwide. “Edge effects” threaten the microclimate and stability of a forest as the ratio of edge to interior habitat increases. Eventually, the ability of a forest to withstand debilitating impacts is broken. Fragmentation of forest ecosystems also contributes to a loss of biodiversity as exotic, weedy species with high dispersal capacities are favoured and many native species are inhibited by isolation. Restoration strategies should therefore often focus first on those areas where intervention can connect existing forest fragments into a more coherent whole. Provide buffer zones and flexibility of land uses: The fixed boundaries of protected areas are not well suited to a dynamic environment unless individual areas are extremely large. With changing climate, buffer zones might provide suitable conditions for species if conditions inside reserves become unsuitable. 58 Buffer zones increase the patch size of the interior of the protected area and overlapping buffers provide migratory possibilities for some species. 59 Buffer zones should ideally be large, and managers of protected areas and surrounding lands must demonstrate considerable flexibility by adjusting 56 Biringer, 2003; Noss, 2001. 57 Noss, 2000. 58 Noss, 2000. 59 Sekula, 2000.

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