Advantages, and limitations of ANR
Within human-modified landscapes, ANR can be an important natural solution for mitigating and adapting to climate change that can also provide economic benefits for local farmers. ANR can enhance the supply of ecosystem services that have been depleted by land degradation, including through protection and rehabilitation of watersheds, increased carbon storage, and recovery of native biodiversity. Because of spatial variability in the ecological and social factors that influence natural regeneration outcomes, ANR provides a highly flexible and adaptive approach to restoration that is context- and site-specific.
Advantages of ANR
Natural regeneration found beneath the grass. ©Bagong Pagasa FoundationA key advantage of ANR is the low requirement for infrastructure and capital investment and the significantly lower costs of implementation and maintenance compared to full tree planting. These qualities contribute to the effectiveness of ANR for household-, farm-, and community-based restoration activities. Enrichment planting and fencing add costs, but can also increase financial and livelihood benefits.
Because of the lower cost and infrastructure requirements, assisted natural regeneration can be an appropriate approach for large-scale forest restoration, particularly following major disturbances. In some cases, site preparation measures alone, such as harrowing and initial herbicide application, can effectively stimulate natural regeneration in intensively used pastures, with no tree planting required.
ANR takes advantage of a natural successional process which ensures that the plant community that is established is well adapted to the site conditions. The naturally regenerating plant community typically comprises a mixture of species, resulting in more diverse, multilayered vegetative cover than from typical reforestation involving the planting of a limited number of species. This diversity enhances habitat quality for local wildlife and environmental stability.
Limitations of ANR
ANR site after grass pressing. ©Bagong Pagasa FoundationThe approach to be used for restoring a site should be determined based on the objectives of restoration, ecological and environmental conditions of the site, socio-economic and cultural context, and availability of budget. In some cases, certain aspects of ANR may limit its applicability in forest restoration efforts.
- As ANR works with natural regeneration, it is most effective where natural regenerants are present at sufficiently high densities or when there is an adequate input of seeds from surrounding forest areas.
- Compared to conventional reforestation, tree growth and stand development are slower, and commercial yields of timber and fiber are lower and less uniform than in intensively managed forest plantations.
- ANR is labor-intensive in early stages, particularly where naturally regenerating trees face heavy competition from weeds and grasses.
- ANR is poorly understood or advocated by policy makers who are focused on active tree planting approaches to reforestation.
It is important to note, however, that ANR is not a mutually exclusive option. It is a flexible and adaptable approach that can be applied in a variety of contexts. It can be combined with enrichment planting of ecologically and/or economically valuable species to meet the specific restoration objectives. It can also be used to restore land fertility to establish an agroforest. The various restoration options available should be combined at the landscape level to balance and optimize the different land management objectives for the wider landscape.