RESTORATION OF ECOSYSTEMS

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Violeta Hevia

In 2004 the Society for Ecological Restoration (SER) defined the restoration of ecosystems as the process of assisting the recuperation of an ecosystem that is degraded, damaged, or destroyed, understood as those having suffered significant loss of their former structural or component characteristics, or that have modified their inherent ecological processes that regulate their development and dynamics (SERI, 2004). The restoration of ecosystems plays an activating role, launching or accelerating processes that promote ecosystem recovery, considering their own capacity for stabilisation and self-regulation in the short-, middle- and long term.

Ecosystems restoration may differ from other approaches to environmental management, such as rewilding or nature conservation. While ecosystem restoration is focused on deteriorated areas, re-establishing ecological balance and the ecosystem’s operability, rewilding seeks to restore natural processes with the minimum human intervention possible, and nature conservation encompasses a more diverse range of measures to prevent irreversible biodiversity loss and guarantee ecosystems’ continuity and the services they provide to humankind.

Additionally, for consideration as restoration of ecosystems, the SER requires the action to be grounded on the following principles:

  1. It must be based on scientifically validated criteria, which requires restoration to stem from one or more hypotheses duly verified and subjected to public scrutiny by the scientific community.
  2. It is necessary to make an ecological diagnosis. As each case is unique, ecosystem restoration should commence with a specific diagnosis of the space to be restored, from a holistic approach including ecosystemic relations, socioeconomic needs and the historical-cultural context on different scales. 
  3. It is necessary to establish an ecosystem of reference to define the ecological processes that need to be recovered. An ecosystem of reference is either a real ecosystem or a detailed conceptual approximation setting the basis for planning the restoration project, its aims, and its assessment. There are four types of ecosystems of reference: 1) self-referential, when the ecosystem contains areas in untouched conditions allowing it to stand as its own referent; 2) those of which we only have information (photographs, documents, etc.) describing the ecosystem before its decline; 3) those in which a portion of the ecosystem remains intact, serving as a reference for another that needs restoration; and 4) the ecosystem of reference that is geographically close and features similar physical conditions, where information is available on the conditions prior to the disturbance to the ecosystem.
  4. The restoration of ecosystems seeks to keep human intervention to a minimum. It identifies and acts on key ecological processes that govern the ecosystem’s functions, activating its self-regeneration capacity. The actions taken should allow the implementation of minimum-intervention mechanisms in future management schemes.
  5. Steps should be defined in which to measure the evolution of the ecosystem so that, in the event of deviation from the initial targets, the restoration measures and actions, or the targets themselves, can be re-oriented (adaptive management models).
  6. Restoration must be flexible and pragmatic, maximising biodiversity, ecological processes and the provision of ecosystems services, without neglecting the ecological, socioeconomic and cultural frameworks.

Interventions enabling the restoration of ecosystems can be classified as active or passive:

  1. Active ecological restoration consists in direct intervention on the structure and characteristics of the degraded ecosystem, aiming to guarantee the existence of a structured and functional ecosystem. An example of active restoration might be sowing (not planting) autochthonous species in areas diagnosed as containing very small source populations of certain species liable to facilitate passive regeneration, which translates as the need for intervention if the restoration of these plant communities is deemed desirable. After sowing, rescuing the ecosystem’s autonomous functioning depends on leaving the seeds free from care or regular watering so that environmental conditions take over and select the species or individuals that are compatible with the system.
  2. Passive ecological restoration is centred on eliminating or minimising the disturbances that cause degradation, leaving the deteriorated ecosystem to recover its own structure and functionality. There is consensus among the scientific community that this possibility should always be considered as a first option, since in many cases the results are comparable and often better than through active restoration.

The choice between active or passive ecological restoration depends on the ecological diagnosis of the area, considering the most realistic and viable options within the available timeframe, and from an environmental, economic, social and scientific-technical point of view. 

The professional teams conducting the restoration of ecosystems need to develop rigorous studies of every specific case, perform precise ecological diagnoses, and guide the adaptive management of the project toward the selected targets.

The execution plan for ecological restoration projects, including follow-up and assessment plans, must be given a suitable timeframe, according to the processes, functions, and structures to be recovered in each ecosystem type (Fig. 1).

Figure 1. Timeframe for Ecological Restoration plans and projects (Adapted from Mola, I., Sopeña, A. and de Torre, R. (editors). 2018. Guía Práctica de Restauración Ecológica. Fundación Biodiversidad del Ministerio para la Transición Ecológica. Madrid. 77 pp).

Bibliography:

Clewell, A., Rieger, J. & Munro, J. (2005). Guidelines for developing and managing ecological restoration projects (2nd ed.) Society for Ecological Restoration International.

Gann, G.D., McDonald, T., Walder, B., Aronson, J., Nelson, C.R., Jonson, J., Hallett, J.G., Eisenberg, C., Guariguata, M.R., Liu, J., Hua, F., Echeverria, C., Gonzales, E.K., Shaw, N., Decleer, K. & Dixon, K.W. (2019). International principles and standards for the practice of ecological restoration. (2nd ed.) Restoration Ecology, S1-S46. 

Higgs, E., Falk, D. A., Guerrini, A., Hall, M., Harris, J., Hobbs, R. J., Jackson, S. T., Rhemtulla, J. M. & Throop, W. (2014). The changing role of history in restoration ecology. Frontiers in Ecology and the Environment, 12(9), 499-506. https://doi.org/10.1890/110267

Lammerant, J., Richard, P., Mark, S., Ben, D., Ian, D. & Guy, W. (2013). Implementation of 2020 EU Biodiversity Strategy: Priorities for the restoration of ecosystems and their services in the EU. Report to the European Commission. ARCADIS (in cooperation with ECNC and Eftec). 

McDonald, T., Gann, G. D., Jonson, J. & Dixon, K. W. (2016). International standards for the practice of ecological restoration–including principles and key concepts. Society for Ecological Restoration.

Mola, I., Sopeña, A. & de Torre, R. (Eds.). (2018). Guía Práctica de Restauración Ecológica. Fundación Biodiversidad del Ministerio para la Transición Ecológica. 

Perrow, M.R., & Davy, A. J. (Eds.). (2002). Handbook of ecological restoration (Vols. 1–2). Cambridge University Press.

Society for Ecological Restoration International Science & Policy Working Group [SERI]. (2004). The SER International primer on ecological restoration. Society for Ecological Restoration International. Available from: https://semspub.epa.gov/work/01/554371.pdf 

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