Rehabilitation and Restoration Of Degraded Forests (PDF) - IUCN

More documents

Recommendations

Info

Chapter 6: Approaches at the site level Proposition 4. An initial (planted) community of pioneer and early secondary species will be short-lived and will not likely be selfsustaining. It is not necessary or even desirable to attempt to simulate natural successional patterns by initiating restoration projects using only pioneer species. In many (though not all) cases, species from the functional groups found in later stages of successions can also be grown in the open in early stages of community development. In many natural successions their delayed colonisation may be as much a consequence of their limited dispersal abilities as their physiological tolerances. This means that many species from mature successional phases can often be planted in relatively open, old-field situations. Corollary: plantings of species from functional groups represented by fast-growing pioneer and early secondary species may be useful as a means of quickly eradicating weeds. Ideally there should be forest remnants nearby from which species from more mature successional stages and other functional groups will colonise. If not, such species can be sown or underplanted beneath this initial canopy. Proposition 5. The sequence in which species are reintroduced to a site is important in determining the assembly trajectory. At a basic level this is obvious; for example, trees are necessary before epiphytes can colonise a site. But at a more fundamental level some important “structuring” species may be needed early in a successional sequence. If they aren’t present then some of the other directly sown or planted species may fail and disappear. This doesn’t mean that all primary forest species must be planted beneath a canopy of early secondary forest species. Rather, facilitation and inhibition can occur during successions and influence successional trajectories. Corollary: the species most able to “structure” a succession are likely to be those that rapidly modify the physical environment or those with large numbers of mutualistic relationships with other plant or animal species. 47
REHABILITATION AND RESTORATION OF DEGRADED FORESTS 48 Proposition 6. The rate at which restoration occurs depends on the extent of the existing environmental stresses. Sites with strongly seasonal climates or low soil fertility are likely to be more difficult to restore. Frequent but unpredictable stresses (e.g. fires, droughts) make it particularly difficult to reassemble new communities. Once restored, however, such communities may buffer some of the stresses (e.g. the more humid microclimate within a new forest may limit the spread of fires). Corollary: It may be necessary to use some non-native species at highly degraded sites that the original species are now unable to tolerate. These can ameliorate the site conditions (e.g. nitrogen fixers that improve soil fertility) and facilitate the subsequent reentry of native species. Proposition 7. Animal are important seed dispersers, particularly in many tropical regions, and thus have an especially important role to play in restoration ecology. Corollary: the propagules of species dispersed by animals will have certain attributes (e.g. fleshy fruit, seed with arils, mostly small to medium fruit size) that make them attractive. Corollary: certain plant species will be unlikely to be dispersed by wildlife and will need to be introduced. These include species with propagules lacking animal-attracting features, those with large fruit or those that fruit infrequently as well as rare species. Corollary: few wind-dispersed species are likely to reach and colonise a site once the canopy closes. Proposition 8. The rate at which additional plant species enter a site once restoration has been initiated depends on the distance from sizable intact forest remnants. It also depends on the extent to which populations of animals capable of dispersing seed from these remnants remain in the landscape. Corollary: little colonisation is likely at isolated sites or in landscapes where only small forest fragments remain and restora-
Page 1 and 2:
Issues in Forest Conservation Rehab
Page 3 and 4:
The designation of geographical ent
Page 5 and 6:
IUCN’s Forest Conservation Progra
Page 7 and 8: REHABILITATION AND RESTORATION OF D
Page 15 and 16: Chapter 2 Degradation REHABILITATIO
Page 21 and 22: Chapter 3 Addressing degradation RE
Page 57: REHABILITATION AND RESTORATION OF D
Page 107 and 108: Chapter 10 Promoting Forest Landsca
Page 109 and 110:
REHABILITATION AND RESTORATION OF D
Page 111 and 112:
Page 113 and 114:
Page 115 and 116:
Page 117 and 118:
Page 119 and 120:
Page 121 and 122:
show all

Rehabilitation and Restoration Of Degraded Forests (PDF) - IUCN

Create successful ePaper yourself

Delete template?

Save as template?