We're kidding ourselves if we think we can 'reset' Earth's damaged ecosystems

Earth is in a land degradation crisis. If we were to take the roughly one-third of the world’s land that has been degraded from its natural state and combine it into a single entity, these “Federated States of Degradia” would have a landmass bigger than Russia and a population of more than 3 billion, largely consisting of the world’s poorest and most marginalised people.

The extent and impact of land degradation have prompted many nations to propose ambitious targets for fixing the situation – restoring the wildlife and ecosystems harmed by processes such as desertification, salinisation and erosion, but also the unavoidable loss of habitat due to urbanisation and agricultural expansion.

In 2011, the Global Partnership on Forest and Landscape Restoration, a worldwide network of governments and action groups, proposed the Bonn Challenge, which aimed to restore 150 million hectares of degraded land by 2020.

This target was extended to 350 million ha by 2030 at the September 2014 UN climate summit in New York. And at last year’s landmark Paris climate talks, African nations committed to a further 100 million ha of restoration by 2030.

These ambitious goals are essential to focus global effort on such significant challenges. But are they focused on the right outcomes?

For restoration projects, measuring success is crucial. Many projects use measures that are too simplistic, such as the number of trees planted or the number of plant stems per hectare. This may not reflect the actual successful functioning of the ecosystem.

Meanwhile, at the other end of the scale are projects that shoot for outcomes such as “improve ecosystem integrity” – meaningless motherhood statements for which success is too complex to quantify.

One response to this problem has been a widespread recommendation that restoration projects should aim to restore ecosystems back to the state they were in before degradation began. But we suggest that this baseline is a nostalgic aspiration, akin to restoring the “Garden of Eden”.

Emulating pre-degradation habitats is unrealistic and prohibitively expensive, and does not acknowledge current and future environmental change. While a baseline that prescribes a list of pre-degradation species is a good place to start, it does not take into account the constantly changing nature of ecosystems.

Instead of a “Garden of Eden” baseline, we suggest that restoration projects should concentrate on establishing functional ecosystems that provide useful ecosystem services. This might be done by improving soil stability to counter erosion and desertification, or by planting deep-rooted species to maintain the water table and reduce dry land salinity, or by establishing wild pollinator habitats around pollinator-dependant crops such as apples, almonds and lucerne seed.

Natural ecosystems have always been in flux – albeit more so since humans came to dominate the planet. Species are constantly migrating, evolving and going extinct. Invasive species may be so prevalent and naturalised that they are impossibly costly to remove.

As a result, land allocated for restoration projects is often so altered from its pre-degradation state that it will no longer serve as habitat for the species that once lived there. Many local, native species can be prohibitively difficult to breed and release.

And present-day climate change may necessitate the use of non-local genotypes and even non-local native species to improve restoration outcomes. Newer, forward-thinking approaches may result in the generation of novel gene pools or even novel ecosystems.

Projects should focus on targets that are relevant to their overarching goals. For example, if a restoration project is established to improve pollination services, then the abundance and diversity of insect pollinators could be its metric of success. As we argue in correspondence to the science journal Nature, restoration should focus on helping to create functional, self-sustaining ecosystems that are resilient to climate change and provide measurable benefits to people as well as nature.

An excellent example of a successful, large-scale restoration project with targeted outcomes is Brazil’s ongoing Atlantic Forest Restoration Pact. This has committed to restoring 1 million hectares of Atlantic forest by 2020 and 15 million hectares by 2050.

This project has clear objectives. These include restoring local biodiversity (for conservation and human use, including timber and non-timber forest products); improving water quality for local communities; increasing carbon storage; and even creating seed orchards that can be either sustainably harvested or used to provide more seeds for sowing as part of the restoration.

This project has clear social objectives as well as ecological ones. It has created new jobs and income opportunities. Local communities are contributing to seed collection and propagation, while the project gives landowners incentives to abide by laws against deforestation. For forests, this is the kind of pragmatic approach that will bear the most fruit.