Advancing the role of natural regeneration in large-scale forest restoration

The global restoration movement is rapidly galvanizing widespread support from multiple sectors of society. As discussed in a recent blog by Peter Besseau, the Global Partnership on Forest and Landscape Restoration is leading the way forward with national and subnational assessments of cost-effective restoration opportunities.  Agricultural productivity, rural livelihoods, biodiversity conservation, landscape connectivity, climate mitigation, and improvement of water resources all stand to benefit from re-growing new forest ecosystems, restoring the regenerative potential of land, and reshaping resilient and diverse productive landscapes.

The opportunity is enormous, as are the challenges. The Bonn Challenge on Forests, Climate Change, and Biodiversity and the New York Declaration on Forests, respectively, call for restoration of 150 million hectares by 2020 and 350 million hectares by 2030. To achieve these ambitious targets, large-scale restoration requires adoption of low-cost, socially acceptable methods that enhance ecological integrity, promote local cultural values, and build upon traditional management practices. In areas that combine the right set of biophysical and socio-ecological conditions, two of the best restoration options for achieving large-scale forest restoration in the world’s tropical regions are natural forest regeneration and assisted regeneration. Natural regeneration should be an essential complement to tree-planting schemes, which are critically needed in areas that will not regenerate on their own.

Seizing on this opportunity, 80 scientists and practitioners of forest and landscape restoration gathered on 19-21 November, 2014 to participate in a workshop entitled “The Role of Natural Regeneration in Large-scale Forest Landscape Restoration: Challenge and Opportunity,” hosted by the Rio Botanical Garden in Rio de Janeiro, Brazil.  The workshop was organized by the International Union for the Conservation of Nature (IUCN), World Resources Institute (WRI), International Institute for Sustainability (IIS), and PARTNERS with support from the Rio de Janeiro Botanical Garden, the United Nations Food and Agriculture Organization (FAO), United Nations Convention on Biological Diversity (CBD), and the Atlantic Forest Restoration Pact (AFRP). A central objective of the workshop was to focus attention on how natural regeneration can be advanced as a highly cost-effective approach to achieve large-scale forest restoration.

A massive oil palm plantation in West Kalimantan, Indonesia. Oil palm is a major contributor to tropical deforestation, and plantations like these can look like natural forest to satellite forest monitors. Photo by Lee Gross.

The benefits of natural regeneration

Known to ecologists as secondary forest succession, natural regeneration is the regrowth and reestablishment of a forest ecosystem following natural or human disturbance. Natural regeneration is an ecological process of self-organization driven by colonization and community assembly of species from source areas, and it therefore depends heavily on the structure and composition of the surrounding landscape and the resilience at the site to be restored. A range of actions, collectively known as assisted natural regeneration, nurtures naturally establishing seedlings and resprouts and can stimulate and accelerate the regrowth process, enhancing the intrinsic resilience of the ecosystem.  Natural regeneration is an open-ended process that expands future options for use of forest land, including further enrichment through planting locally important species that are well adapted to the region and are utilized by local people and wildlife.

In addition to low overall cost, natural regeneration promotes local genetic and functional diversity and enhances local cultural values and traditional management of timber and non-timber products. The plant and animal species that arrive and establish are adapted to the site and to each other, promoting rich ecological interactions and synergies that link components of the surrounding landscape. In this way, naturally regenerating forests contribute to landscape heterogeneity, connectivity, biodiversity conservation, and resilience.

Natural regeneration is a viable restoration option in areas where soils have not been highly degraded, diverse natural seed sources grow nearby, and seed-dispersing fauna are present. Ideal locations for promoting natural regeneration are in the buffer zones of existing protected areas and where patches of vegetation remain within the landscape. A growing number of cases document successful large-scale natural regeneration throughout the tropics. Scientific research shows clearly that natural regeneration is a highly cost-effective approach to restoration in both drylands and montane regions.

Expanding areas of naturally regenerating forests in tropical landscapes will enhance and stabilize multiple ecosystem services and provide safe havens for many forest-dependent animal and plant species that are vulnerable to extinction. Much is at stake. For these reasons, scientists attending the Rio workshop called for the formation of a global partnership to promote natural regeneration at large spatial scales. The proposed new global partnership will work to promote the inclusion of natural regeneration in the portfolio of restoration options and to strengthen capacity to identify and map priority areas for natural regeneration at large spatial scales. The new partnership will work in concert with other global restoration initiatives, including those focused on Forest and Landscape Restoration and agroforestry.

Measuring trees in a second growth forest in Northern California, USA. Photo by Courtney Wallace.

The challenges of natural regeneration

Given the high cost-effectiveness of natural regeneration, why it this approach to forest restoration underutilized, and what factors present obstacles to widespread implementation? Workshop participants addressed these questions in wide-ranging discussions. Secure land tenure and property rights are major obstacles to setting aside land for natural regeneration. Even in cases of private ownership, letting fields go fallow is viewed as irresponsible land management. Disorderly tangles of vegetation signal that land is abandoned, inviting colonization by landless squatters. Compared to tree planting schemes, spontaneous canopy development, biomass accumulation, and species colonization can be slow and patchy. Moreover, in most cases, landowners receive far lower financial benefits and technical support than if they establish orderly reforestation plantations. Natural regeneration and fallow management, which have been widely practiced by shifting cultivators for millennia, are seen as “backward” in today’s high-tech world.

Natural regeneration may also entail substantial costs, including fire protection, fencing to exclude cattle grazing, and patrolling to eliminate hunting and excessive harvesting. As with tree planting, opportunity costs of forfeiting agricultural production also must be considered. These costs can be minimized in sites close to protected areas that are already regularly patrolled and where regenerating forests can provide income through ecotourism.

A further challenge is the monitoring of natural regeneration using satellite imagery. Many areas of naturally regenerating forests are small and patchy, and are easily overlooked. Even in areas of greater spatial extent, natural forest regeneration can be confused with other tree-based land-cover types such as commercial tree plantations (including oil palm), restoration plantations, and selectively-logged forest. For these reasons, accurate global assessments of the actual extent of naturally regenerating tropical forests have not yet been conducted.

Extensive natural regeneration in the upper Guapaçu Valley watershed in Rio de Janeiro State, Brazil. Low hills are part of the privately managed Reserva Ecologica de Guapiaçu (REGUA). Photo by Robin Chazdon.

Making natural regeneration happen

These challenges can and must be overcome to restore functionality and vitality to tropical forests globally and to reinforce conservation activities in remaining intact forests. One critical step is to forge new multi-sectorial collaborative approaches to planning and implementing land-use policies that incentivize landowners to nurture young forests. Enabling policies need to be implemented to remove disincentives, establish land tenure and property rights, empower communities, improve local governance, and popularize natural regeneration. Incentives are also needed, including direct payments to landowners, access to knowledge and tools, and the creation of new markets for ecosystem goods and services produced by regenerating forests.

Private landowners are critically important allies in landscape restoration efforts based on natural regeneration. In Brazil, in the privately owned Reserva Ecologica de Guapiaçu (REGUA) in Rio de Janeiro state, forests on the lower slopes of the Guapiaçu valley watershed that were cleared for farming and ranching have regenerated naturally over the past 30 years. Since 2001, hundreds of hectares of heavily degraded pasture in lowland areas are being restored through high diversity tree plantings (see figure). Restoration scientists and practitioners are working to develop methods for assessing the likely success of natural regeneration based on vegetation, soil, and landscape indicators, for mapping priority areas and landscape connectivity, and for monitoring successes and failures of natural regeneration as components of large-scale restoration projects.

The case for advancing the role of natural regeneration and assisted regeneration in global forest restoration is compelling and urgent. Nature is waiting to join forces with us to restore tropical ecosystems. We must seize the opportunity now, before it is too late.