Conservationists in conflict
Many ecologists seek to restore damaged ecosystems to their original states. But others argue they are being ‘unrealistically nostalgic’ and that invading species open up new ecosystems
WORDS AND their meanings can be every bit as tricky in science as they are in literature. The phrases scientists choose to portray natural phenomena can shape our perceptions of the world, and affect crucial decisions made by policy-makers.
The “novel ecosystems” theory, energetically promoted by a group of influential ecologists in recent years, is a case in point. The theory’s advocates say they are simply describing unprecedented changes in ecosystems, and warning of their consequences.
Their critics claim that the way they have characterised these changes could have a disastrous impact on environmental policy. They say the theory, at least as currently expressed, hands governments and corporations an easy excuse to abandon core conservation targets.
It is no accident that this controversy has arisen in the realm of restoration ecology, a new science that seeks to advance the recovery of ecosystems, where they have been degraded or even destroyed by human activities.
It is a cutting-edge discipline in its active engagement with the enormous complexity of entire ecosystems in the field.
There have been successes in ecological restoration. For example, the Alcoa corporation has been restoring most of the rich biodiversity of a jarrah (eucalyptus) forest in southwestern Australia, after its mining operations have entirely erased not only all the forest vegetation, but also four metres’ depth of soil.
Over the last decade, restoration has become a front-line strategy in global conservation. At home, we have seen expanding restoration of native woodlands and, with more difficulty, of bog ecosystems. Restoration is now written large into European policy, with the EU committed to restoring 15 per cent of degraded landscapes by 2020.
And yet, just at this breakthrough moment, novel-ecosystem theory appears to be undermining, from the inside as it were, basic restoration principles that have only recently been established.
One of the foundational pillars of restoration science is that restoration projects should be based on “historical reference systems”. If you want to restore native oak woodland on a degraded site, for example, you should reconstruct in detail a model of its previously healthy condition. This model becomes the template for the biological communities and ecosystem functions appropriate to your project.
Novel-ecosystem theorists, however, argue that many, perhaps most, of today’s ecosystems are changing so rapidly, and so unpredictably, that attempting to restore to an historical reference system is often a waste of scarce resources.
They say that global human impacts on nature, ranging from climate change to the introduction of invasive alien species, are creating “novel” biological communities. And these new combinations of species may also create unprecedented ecosystem dynamics.
They theorise that such systems have crossed “irreversible thresholds” – radically altered soil composition, for example – that make restoration to historical conditions impossible.
The best we may be able to do, they conclude, is to manage these systems for whatever ecosystem services they can provide. Goodbye oakwoods and bogs, hello rhododendrons and Japanese knotweed as seen at home.
One of the first major papers on the subject, Ecological Restoration and Global Climate Change (2006) stated baldly that: “Valuing the past when the past is not an accurate indicator for the future may fulfil a nostalgic need, but may ultimately be counterproductive in terms of achieving realistic and lasting restoration outcomes.”