Assisted Natural Regeneration is an essential tool to restore forests and ecosystems in Latin America, and combining it with active restoration could be the key to achieving even richer biodiversity.
What is Assisted Natural Regeneration (ANR) and what are its benefits?
Assisted natural regeneration (ANR) is a collection of approaches that seek to remove disturbances to forests that are caused by humans, such as deforestation and fire, to facilitate and accelerate the regeneration process (Chazdon 2014). It is a spectrum of activities, starting as soon as people begin to intervene to assist, accelerate, and enrich the natural regeneration process as the baseline state of the land is more degraded and less resilient to multiple human impacts (Chazdon et al. 2021).
ANR removes or reduces barriers to natural forest regeneration such as soil degradation, invasive weedy species, grazing, and human activities like fire and wood harvesting (Chazdon et al. 2017). ANR also protects tree seedlings from the undergrowth and highly flammable plants. As a consequence, forests grow faster than they would without assistance (Shono et al. 2020).
ANR provides several benefits:
It provides job opportunities for local communities.
It contributes to strengthening biodiversity.
Forest restoration successes with natural regeneration
In a global meta-analysis conducted by Crouzeilles et al. (2017) on the ecological drivers of forest restoration success, researchers looked at 133 studies and found that natural regeneration obtains more success in tropical forest restoration than active restoration (e.g., planting nursery-grown seedlings). The research also shows that active restoration doesn't accelerate biodiversity recovery more than ANR.
Naturally regenerated systems provide additional habitat, shelter, and food sources to support higher animal biodiversity.
Naturally regenerated systems provide additional habitat, shelter, and food sources to support higher animal biodiversity. For each taxonomic group assessed in the study, including bird populations, restoration success is more elevated in ANR than in active restoration, except for mammals.
These compelling findings suggest that restoration strategies should favor ANR when the social and ecological conditions are favorable and biodiversity conservation is a high priority. Using a mix of both restoration approaches might be the key to achieving a richer species pool. Conditions that favor successful restoration through ANR approaches include proximity to forest patches, lack of soil disturbance, and protection of young regenerating sites from harvesting or disturbances (Chazdon et al. 2020). Not all candidate sites for restoration are appropriate for ANR.
The Role of ANR in the Uchapa-Pimienta Watershed in Honduras
ANR actions have been prioritized by our local project team in Olanchito, Honduras to respond to the scale of loss of forest due to the particularly severe outbreaks of the Southern pine bark beetle (Dendroctonus frontalis) that have affected Honduran forests in recent years. The majority of the pine-oak forest in the area of influence of the project, in particular the Uchapa-Pimienta watershed in the Department of Yoro, has been heavily impacted.
ANR has proved to be an effective way to reduce the impact of the destructive beetle and restore the degraded areas.
ANR has proved to be an effective way to reduce the impact of the destructive beetle and restore the degraded areas. Using ANR methods in patches of trees that are still not affected by the infestation nourishes propagation material and attracts dispersal agents (birds, bats, mammals, etc.) within those sites.
The Municipality of Olanchito, EcoLogic, and local partners are implementing the following ANR activities:
Community Monitoring: We conduct visual evaluations of the regeneration and support local communities' training. Community involvement is critical to preserving the progress achieved through ANR.
Fire Prevention: Local brigades build and maintain firebreaks to reduce the likelihood that fires will destroy regenerating areas.
Weed control: We routinely clear weeds around regenerating seedlings to help accelerate their growth.
Fire Control: In the eventuality of a forest fire, the Environmental Unit of the Municipality of Olanchito and local partners take action to control and extinguish it.
Demarcation and signage: We mark areas where natural regeneration occurs to prevent further disturbances.
Prevention and Enforcement Against Illegal Logging: Forest guards and military police conduct monitoring patrols to detect illegal logging and take action against it.
In April 2022, EcoLogic, the Municipality of Olanchito, and the Association of Water Committees of the Southern Sector of Pico Bonito National Park (AJAASSPIB) renewed a 3-year commitment to the conservation of the 6,111-hectare Uchapa-Pimienta watershed that provides water to approximately 50,000 residents. As forest fire season approaches, community brigades stand at the ready.
We look forward to continuing to update you on these efforts.
Alves, Julio, Mariana Oliveira, Robin L. Chazdon, Miguel Calmon, Andreia Pinto, Eduardo Darvin, and Bruna Pereira. 2022. The Role of Assisted Natural Regeneration in Accelerating Forest and Landscape Restoration: Practical Experiences from the Field. Practice Note. São Paulo: WRI Brasil. Chazdon, R. L. 2014. Second growth: The promise of tropical forest regeneration in an age of deforestation. University of Chicago Press, Chicago, IL. Chazdon, R. L., D. Lindenmayer, M. R. Guariguata, R. Crouzeilles, J. M. Rey Benayas, and E. Lazos. 2020. Fostering natural forest regeneration on former agricultural land through economic and policy interventions. Environmental Research Letters 15:043002; https://iopscience.iop.org/article/043010.041088/041748-049326/ab043079e043006/pdf. Chazdon, R. L., D. A. Falk, L. F. Banin, M. Wagner, S. Wilson, R. C. Grabowski, and K. N. S. Suding. 2021. The intervention continuum in restoration ecology: Rethinking the active-passive dichotomy. Restoration Ecology e13535. Chazdon, R. L., B. Bodin, M. R. Guariguata, D. Lamb, B. Walder, U. Chokkalingam, and K. Shono. 2017. Partnering with nature: The case for natural regeneration in forest and landscape restoration. FERI Policy Brief; www.feri-biodiversity.org/resources, Montreal, Canada. Crouzeilles et al., Ecological restoration success is higher for natural regeneration than for active restoration in tropical forests, Science Advances, November 2017; 3: e1701345 Shono, K., R. Chazdon, B. Bodin, S. J. Wilson, and P. Durst. 2020. Assisted natural regeneration: harnessing nature for restoration. Unasylva 252 71:71-81.