Ecological restoration? Yes, but to what extent?

Natàlia Blázquez Pallí  is a postgraduate student who wrote this article as part of her Euroleague for Life Sciences course work at Lincoln University.  

What is ecological restoration?

According to SER (2004), ecological restoration is achieved “when the system contains sufficient biotic and abiotic resources to continue its development without further assistance or subsidy. It will sustain itself structurally and functionally. It will demonstrate resilience to normal ranges of environmental stress and disturbance. It will interact with contiguous ecosystems in terms of biotic and abiotic flows and cultural interactions”. Restoration usually involves the management of a degraded ecosystem and the recovery of its natural characteristics, i.e. at pre-disturbance conditions.

What is good ecological restoration?

In order to assess how well an ecosystem is restored, SER (2004) listed nine ecosystem attributes considered to be a restoration guideline and a model of positive restoration development, but other authors have suggested a more practical approach with only three attributes: vegetation characteristics, diversity of species and ecosystem processes (Ruiz-Jaen and Mitchell Aide, 2005). Ecological indicators are the tools used to assess restoration success (Dale and Beyeler, 2001) and reference ecosystems are used as a model and as a success evaluation tool (SER (2004), Hobbs and Harris (2001)).

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From left to right, the first two pictures are two examples of ecological indicators, in this case of absence or presence of invertebrates. The third picture is the reference ecosystem of a kānuka forest of the Canterbury plain and the picture on the right belongs to the restoration project in the Eyrewell Forest, aiming to replicate its reference ecosystem. In addition, this last picture also shows the exotic pine forest that provides good habitat for endemic species, becoming an example of a novel ecosystem.

What is the role of history in ecological restoration?

Gathering information about the ecological history of our planet is essential to identify reference ecosystems and define restoration goals, but pre-disturbance conditions tend to go too far back and do not seem very realistic. Furthermore, natural environmental variation has prevented the long-term establishment of an ecosystem that could be used as an historic standard (Jackson and Hobbs, 2009) and, with the expected climate change, what once was “natural” and self-sustaining may not be anymore. Therefore, ecological restoration needs to focus on ecological fidelity when feasible, but it should also be flexible and consider new and emerging ecosystems when appropriate.

So, what would be a good implementation method for ecological restoration?

Ecological fidelity to a certain degree

The recovery and conservation of endemic, native or local biodiversity is the maximum priority of restoration ecology. However, is this fidelity to historical references a non-negotiable target? Are pre-disturbance conditions realistic? Besides the difficulty of replicating a past ecosystem, practitioners should also consider the viability of such ecosystem in the present conditions. Is it worth to try and risk failure or would it be better to settle halfway? The practice of ecological restoration may benefit from a gradual approach, where objectives are set progressively, according to restoration performance and success, the response of the restored ecosystem on its own, but also its interaction with the surrounding ones.

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The Port Hills vegetation restoration project, where ecological restoration is being used for conservation and protection of native and endangered species, but also as a means to control soil erosion and water conservation.

Recognition of novel ecosystems

Novel ecosystems emerge from the interaction among invasive species, climate variability, land use changes and other biogeochemical factors (Hobbs et al. (2006), Seastedt et al. (2008)), and may even develop into the perfect habitat for the conservation of endangered species. An example of this weird combination is the exotic Eyrewell pine forest in Canterbury, New Zealand, which has become an important haven for indigenous vegetation and invertebrates (Meurk et al. (1995), Brockerhoff et al. (2005), Berndt et al. (2008), Harding (2009)). Some researchers would argue that ecological fidelity does not allow room for novel ecosystems but, why are new ecosystems worse or less valuable in terms of biodiversity? Even if some of the components are exotic, it does not mean that the whole ecosystem is exotic, since the interaction with existing native species and processes can turn out to be particular of the region and even unique. Furthermore, established novel ecosystems are successful in their form, since they have emerged, developed and succeed on their own. In addition, these ecosystems are adapted to current environmental conditions and, for this reason, they may be better prepared for what is to come. Hence, is it okay to ignore an unique ecosystem, even with exotic influences, to restore another one that may not be sustainable because circumstances have changed too much? It is crucial that we learn how novel ecosystems function and under what circumstances they are sustainable (Hobbs et al. (2006), Seastedt et al. (2008)). For instance, the combination of historic and novel ecosystem patches may prevent a total collapse if the restoration process fails (Jackson and Hobbs, 2009).

Participative and consultative process

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The Lake Ellesmere restoration project, where all stakeholders are involved in the restoration process, ensuring commitment from all parts, consideration of all perspectives and allowing a greater success rate.

Not all restoration projects share the same goals and, therefore, they should not completely share their practical approach nor follow the same methodology for planning or assessing restoration performance (Christensen, 2014). The context of the project should be taken into consideration, as it can affect its characteristics and turn it into something completely different. Local stakeholders (inhabitants, farmers, managers, politicians, experts, etc.) need to be involved in project planning to limit failure risks and ensure ecological, economical and societal success (Couix and Gonzalo-Turpin (2015), Kozak and Piazza (2015)). A good example of such collaboration would be the Lake Ellesmere’s restoration project in New Zealand.

Integrative approach

Ecological restoration should be seen as an integrative tool to achieve other targets besides biodiversity conservation. People could benefit from this practice, not only from the ecological perspective, but also from the economical and societal point of view, for example, with the recovery of ecosystem goods and services, the integration of nature into people’s lives, and the mitigation and adaptation to climate change impacts (Locatelli et al., 2015).

Restoration ecology is currently a hotspot science. It is evident that a lot of research has been done on this subject, but restoration processes are still too open to ecosystem variability, priorities and interests of the involved parties. Finding effective methods of assessing the success of ecological restoration and resolve which measures are more appropriate and successful depending on the context should be a priority. The development of more specific tools to support these decisions will be crucial, moreover in the light of climate change, the biggest challenge of all.

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