As human populations become increasingly urbanized, the abandonment of rural landscapes is allowing forests to naturally regenerate in many parts of the world and decreasing the overall global rates of deforestation significantly (FAO global forest resources assessment). Assisted Natural Regeneration (ANR) is a method of aiding the natural process already underway on abandoned agricultural sites to encourage, and improve the process of natural regeneration (see here ).
The power of the ANR approach comes from its ease of application, assisting volunteer saplings, rather than planting new ones, for the majority of the regenerating forest. By giving established saplings an improved chance to thrive and avoiding the high costs and generally lower success rates of transplanting, ANR methods are proving to be an effective low cost approach to reforestation. Additionally, by focusing on the conversion of agricultural land to forest, the relative impact of ANR activities in terms of environmental goods and services, natural capital, and biodiversity is especially high. Unlike many types of ecosystem restoration, ANR projects are assured success because in most cases natural regeneration is already underway, or is at least ecologically favored in the long term.
While ANR is already proving itself a powerful tool in the effort to reverse global deforestation, it is important to recognize its limitations and avoid making it into a panacea. ANR works well only if natural regeneration is already happening, which generally requires that the deforested area is near to remnant forests and thereby sources of tree seeds. Even in the case of well-suited sites for ANR, the tree species that establish may be quite different from the composition of the original native forest that once stood on that site. Further restoration work can be done, including transplanting under-represented species into an ANR site, but this can significantly increase costs. Regenerating any forest that truly equals a native, mature forest’s ecological value is probably impossible or at least exceedingly costly on anything but the longest of time scales. Because a mature, native forest in any region is an intricate collection of diversity and functions, it should be kept in mind that no form of regeneration is a substitute for the conservation and preservation of existing undisturbed forests.
ANR represents a great movement in reforestation, both in terms of its impact and its example. By assisting in a beneficial process that is already underway and favored by natural processes, ANR does what all good agents of change should do, that is find the lowest hanging fruit with the greatest value, pick it and plant it.
BBC: Locals 'can play key role in helping forests recover': http://www.bbc.co.uk/news/science-environment-15619703#
BBC: ‘No substitute’ for virgin forests:
FAO: Assisted Natural Regeneration of Forests: http://www.fao.org/forestry/anr/en/
FAO global forest resources assessment:
Aide, T. M., Zimmerman, J. K., Pascarella, J. B., Rivera, L. and Marcano-Vega, H. (2000), Forest Regeneration in a Chronosequence of Tropical Abandoned Pastures: Implications for Restoration Ecology. Restoration Ecology, 8: 328–338. doi: 10.1046/j.1526-100x.2000.80048.x