Aliens, natives and novel ecosystems

In a recent comment in Nature, titled “Don’t judge species on their origins”, Mark Davis and others call for judging ecosystems and the species therein in terms of their ecosystem functions, and not according to whether they are native or introduced to a region. Basically, they argue that the paradigm of conserving the native vegetation is outdated in a globalized world that subject to various pressures and changes. Rather, they say that

It is time for scientists, land managers and policy-makers to ditch this preoccupation with the native–alien dichotomy and embrace more dynamic and pragmatic approaches to the conservation and management
of species — approaches better suited to our fast-changing planet.

According to the authors, managers and policy makers should rather look at the physical impact of a species in terms of changes of ecosystem services and functions to decide about interventions, as

The effects of non-native species may vary with time, and species that are not causing harm now might do so in the future. But the same is true of natives, particularly in rapidly changing environments.

One might think that Nature has taken a fancy to the subject – the article reminded me of a previous News Feature on “novel ecosystems” by Emma Marris (Ecology: Ragamuffin Earth) which reports about several studies that have looked at “novel” or “emerging” and the ecosystem services and biophysical functions they provide. I believe that it is valuable to question the “conventional” conservation objective (see e.g. Brooks 2006), but of course ecosystem functions are not all there is for conservation, as “novel ecosystems” will inevitably decrease the available space for the already threatened “traditional ecosystems”.

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