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Forest Restoration in Landscapes

Forest Restoration in Landscapes

46 J. Morrison et al

46 J. Morrison et al estimate is difficult to come by or there are severe limits to the number of individuals that are possible, the bottom line is that a target level should be chosen that represents the largest conceivable achievable population level. For restoration purposes, the specific needs of each focal species must be analysed individually. A number of related metrics, including minimum patch size, connecting patches to enlarge the effective habitat area or feature (breeding, feeding, or nesting areas/cavities), corridor width, specific habitat requirements (plant species), access to water, etc. must be considered. During the course of the analysis to determine the habitat and total area requirements for each species, it should quickly become clear if there is not enough habitat necessary for a viable population of a particular species—and restoration will be necessary. This is frequently the case in those ecoregions that have been highly degraded. The reconnection of now disjunct habitat patches is a common application of forest restoration activities. This is the focus of the current work in the Terai Arc in the Eastern Himalayas: reconnecting 10 protected areas by encouraging the growth of communitymanaged forests (Fig. 6.2). Tigers are loath to cross more than 5km 2 of nonhabitat, but the existing protected areas are not large enough to maintain viable populations of tigers. Some mixing of the respective populations is desirable. Therefore, community forests are being encouraged where gaps in forest cover are noted between the existing protected areas. This will allow tigers, greater-one horned rhinoceroses, and Asian elephants to disperse between patches of prime habitat. Restoration is an important activity in other fragmented ecoregions that still contain large carnivores, including for jaguars in South America’s Atlantic Forest and for wolves and grizzly bears Figure 6.2. Reconnecting protected areas (dark) with forest restoration (light). (Source: WWF.)

in the ecoregions of the Northern Rockies of North America. 2.3. Ecological and Evolutionary Processes The many evolutionary and ecological processes that create and sustain biodiversity are complex, and often poorly understood. Gene flow, migration, pollination, seed dispersal, predator–prey dynamics, and nutrient cycling are some of the many that should be considered when a conservation plan is developed. All of these processes can potentially benefit from restoration activities, because many species (and the processes that they are involved in) will respond positively to restored forest quality, but some of them will benefit more obviously than others. Gene flow and migration can directly benefit from restored forest corridors, as in the above examples. Likewise, if key processes such as pollination or seed dispersal are threatened by insufficient forest area to support the species that are performing these functions, restoration activities would be appropriate. In some regions, reduced forest cover threatens to throw the area into a not-easilyreversible regional climatic shift. Restoration of forest cover (that simultaneously meets finer scale representation targets and is configured to maximise forest block size for area-sensitive species) would be a high priority activity. The Terai Arc is also a good example for this set of conservation goals. By reconnecting disjunct forest patches and thus tiger subpopulations, the ecological processes of subadult dispersal, gene flow, and restoration of predator–prey dynamics can be restored. Because systems with large predators are often dominated top-down forces (in this case elephants and tigers), the reintroduction of tigers and elephants across the entire landscape will help put a number of natural ecological processes back into a more natural dynamic balance. However, the needs of finer-scale habitat specialists (particularly for breeding or feeding) within the larger area should not be overlooked. 6. Restoration as a Strategy to Contribute to Ecoregion Visions 47 2.4. Environmental Change Planning for inevitable environmental change (even without the additional spectre of anthropogenic climate change) is a key precept in conservation. Ecological systems are by their very nature dynamic, and it is important to incorporate large habitat areas and sufficient connectivity between habitat areas in order to build resiliency into the protected area network. Increased connectivity is the main option available to conservation planners trying to anticipate the effects of anthropogenic climate change. Species’ ranges are already beginning to shift in latitude and altitude; this is true not only for animals but for plant species as well. Again, reconnecting now disjunct habitat patches through restored forest corridors is an appropriate application for forest restoration activities to help migration to keep pace with changing conditions. In addition, managing the landscape in such a way that it provides more flexibility for species and gene flow in times of stress is an important element of restoration. This connectivity strategy will be important for every ecoregion across the planet to consider. Ecoregions likely to be faced with this threat in the near term are tropical montane ecoregions that contain significant topographic relief. Climatological changes are concentrated in narrow bands, and maintaining altitudinal connectivity will be critical for allowing habitats to shift in response to changing temperature and moisture regimes. Restoration activities are important for all ecoregions where human activities have fragmented the ecoregion, and this includes most ecoregions. Rising temperatures and changing precipitation patterns will cause natural communities to shift latitudinally and altitudinally. Without restoration to reconnect fragmented habitat patches with corridors, natural communities will have great difficulty shifting across human-dominated landscapes. A more specific example of the need for restoration will be in tropical coastal ecoregions with mangroves. As sea level continues to rise, mangrove belts will tend to shift inland (Fig. 6.3). However, if the landward edge of the mangrove belt has been degraded, which it commonly is, space and

Forest Landscape Restoration - IUCN
Landscape restoration