PerspectiveConservation

Committing to ecological restoration

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Science  08 May 2015:
Vol. 348, Issue 6235, pp. 638-640
DOI: 10.1126/science.aaa4216

At the September 2014 United Nations Climate Summit, governments rallied around an international agreement—the New York Declaration on Forests—that underscored restoration of degraded ecosystems as an auspicious solution to climate change. Ethiopia committed to restore more than one-sixth of its land. Uganda, the Democratic Republic of Congo, Guatemala, and Colombia pledged to restore huge areas within their borders. In total, parties committed to restore a staggering 350 million hectares by 2030.

The ambition affirms restoration's growing importance in environmental policy. These new commitments follow the 2010 Aichi Convention on Biological Diversity (to restore at least 15% of degraded ecosystems globally) and the 2011 Bonn Challenge (to restore 150 million hectares). Particularly when accompanied by policies to reduce further losses (as in the New York Declaration), restoration of such magnitude holds promise to address global environmental concerns.

Achieving this promise requires careful thought about how we restore ecosystems (1, 2). We outline four core principles of scientifically based, workable, and comprehensive restoration (3) that can provide appropriate best practice guidelines in legal, policy, and planning efforts.

There is little question that ecological restoration can provide substantial benefits that enhance quality of life (4). A considerable body of science suggests that restoration can guide establishment of complex self-sustaining interactions between biota, biophysical features, and processes that compose an ecosystem (5, 6). The science also emphasizes the challenging nature of the endeavor: Our interventions rarely achieve full recovery, and uncertainty is to be expected in dealing with natural recovery processes (7, 8). Continuing environmental change further challenges the notion of recovery (9).

Four principles for planning restoration. The use of four principles identifies trade-offs in the planning process and the extent of departure from the full opportunities presented by comprehensive ecological restoration [example after (25)].

Some have thus questioned whether declarations of intent to restore will in fact result in substantive restoration of degraded land (10, 11). Others have cautioned that these declarations may spur actions that compromise biodiversity: for instance, by replacing ancient grassy biomes with forest plantations (12) or by planting species in climatic zones where they may not persist (13). Others emphasize that a focus on one specialized goal (e.g., climate change mitigation) might not deliver intended benefits because of complexity in ecosystem dynamics in ways and over time scales not fully understood (14, 15).

Specialized programs such as compensatory mitigation, endangered species conservation, and ecosystem service delivery can be a useful contribution to—but are not synonymous with—ecological restoration (16, 17). Such distinctions are not trivial because projects undertaken in the name of restoration may in fact be something different and, in many cases, have been demonstrated to achieve neither restoration nor their intended purposes (17, 18). Delivery of diverse benefits will depend on how on-the-ground efforts are conceived and implemented (7, 8). Avoiding mistakes on a grand scale requires clear practice principles (10).

FOUR PRINCIPLES. We advocate considering four principles when planning restoration. The degree to which each principle is achievable will vary on the basis of social and ecological context. By taking into account these comprehensive principles, trade-offs inherent in specialized projects are avoided, which increases the prospect of sustainable and valuable overall outcomes (see the figure).

1. Restoration increases ecological integrity. Restoration initiates or accelerates recovery of degraded areas by prioritizing the complexity of biological assemblages, including species composition and representation of all functional groups, as well as the features and processes needed to sustain these biota and to support ecosystem function (3, 4).

2. Restoration is sustainable in the long term. Restoration aims to establish systems that are self-sustaining and resilient; thus, they must be consistent with their environmental context and landscape setting. Once a restoration project is complete, the goal should be to minimize human intervention over the long term. When intervention is required, it should be to simulate natural processes that the landscape no longer provides (e.g., fire or invasive species removal) or to support traditional practices of local communities (8, 9).

3. Restoration is informed by the past and future. Historical knowledge, in its many forms, can indicate how ecosystems functioned in the past and can provide references for identifying potential future trajectories and measuring functional and compositional success of projects (19). However, the unprecedented pace and spatial extent of anthropogenic changes in the present era can create conditions that depart strongly from historical trends (9). Often, then, history serves less as a template and more as a guide for determining appropriate restoration goals (19, 20).

4. Restoration benefits and engages society. Restoration focuses on recovering biodiversity and supporting the intrinsic value of nature (21). It also provides a suite of ecosystem services (e.g., improved water quality, fertile and stable soils, drought and flood buffering, genetic diversity, and carbon sequestration) that enhance human quality of life (e.g., clean water, food security, enhanced health, and effective governance) (22). Restoration engages people through direct participation and, thus, increases understanding of ecosystems and their benefits and strengthens human communities (4).

Parties to the U.N. Declaration will consider a variety of ways to achieve the new restoration commitments. We advocate adoption of all four principles as normative standards that assess intent at the planning stage, developed in conjunction with consideration of levels of uncertainty (in both the means and ends), the degree to which each principle could be attained, and legal or regulatory frameworks (23). Components that constitute ecological integrity will differ across ecosystems; they will need to be described and made practical through best practice guidelines (4). The degree to which restoration can be self-sustaining will depend on landscape context; ongoing interventions may be required in some cases to ensure ecological goals consistent with local context are met (6). Flexibility regarding the degree of historical fidelity will be needed to ensure success in rapidly changing environments (9). Ethical considerations can supersede direct societal benefits, particularly when ecocentric ideals are followed (21).

To achieve new restoration commitments, it will be tempting to consider specialized projects that emphasize one principle rather than attending to the full suite of potential opportunities. Degraded lands could be converted to carbon farms, where monocultures of fast-growing tree species are planted and managed to optimize carbon sequestration (24). Green infrastructure could provide vegetation that fixes carbon and increases permeable surfaces (25). As valuable as these strategies may be, they alone do not constitute comprehensive ecological restoration. To contribute to our commitment to restore, the scope of these strategies should be broadened to include all restoration principles (see the table).

We urge parties to utilize all principles in their planning and to maintain a broad purpose. Although a comprehensive plan may require a more integrative approach than one aimed toward a specialized purpose, considering all four guiding principles is most consistent with ecological and social science and most likely to realize accepted benefits of restoration without net ecological loss.

Our four principles provide a necessary foundation to achieve sustainability and resilience into the future. Ecosystems that are structurally and functionally diverse are more likely to be durable and capable of adapting to future challenges of climate change, introduced species, and land-use change and they can be sustained with a declining investment of human and financial capital over time. Involving people through multiple avenues—from participation to consumption of ecosystem services to cultural renewal—can promote public engagement and stewardship of local ecosystems. Adherence to these principles will add clarity, accountability, and accomplishment in this new era of embracing ecological restoration as an environmental policy tool.

References and Notes

  1. Global Partnership on Forest and Landscape Restoration, Pamu Berekum site; www.forestlandscaperestoration.org/learning-site-pamu-berekum.
  2. Acknowledgments: We thank anonymous reviewers, N. Barger, R. Hobbs, and S. Murphy for comments. This work was supported by the National Socio-Environmental Synthesis Center (SESYNC) under funding received from the U.S. National Science Foundation DBI-1052875.

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