By Jamie Steer 21/12/2018

Here are more comments from my interview with Kim Hill:

‘…each species we lose puts the entire ecosystem at risk of collapse’ 

‘Without the species that are adapted to these native environments a whole ecosystem will eventually collapse’

Some people say that our ecosystems are going to collapse under the weight of introductions, that our ecosystems are essentially going to die. This is something that we’ve heard for many years now, particularly in the context of forest ecosystems; that they will surely collapse at some point in the near future and we’ll have deserts or something like savannas presumably.

As the Parliamentary Commissioner for the Environment recently wrote:

‘…possums, rats and stoats … are bent on destroying our native forests…we cannot allow our forests to die’ (Parliamentary Commissioner for the Environment, 2011)

It’s pretty scary stuff. But it really hasn’t happened, and I’d put it to you that it is not going to happen any time soon either. What is going to happen is that our ecosystems are going to change: a far less catastrophic outcome. Possum herbivory, for example, will not cause forests to collapse. What will happen is their species composition will likely change over time. Tree species that are more palatable to possums and other herbivores will become less numerous in the canopy over time and those that are less palatable will become more numerous.

Most of the species that we suspect of precipitating collapse have been out there in our forests for over 100 years now and yet I’m sorry but almost everywhere you look it’s still wall-to-wall forest. I think what is actually going to happen is that our forest ecosystems will continue to change, and their species compositions will change, as they always have in response to new arrivals and novel influences.

Novel ecosystems

The concept of ‘novel ecosystems’ was introduced to the ecological literature in the mid-naughties for just these reasons – to speak to the fact that ecosystems around the world have changed and continue to change, both in response to introduced species and a range of other factors, but to emphasise that these ecosystems are generally still hugely vital, prosperous and valuable.

Ecologist Richard Hobbs and colleagues had this to say about these novel ecosystems back in 2009 and what it might mean for some of our thinking moving forward. He wrote that:

‘…cultural norms of nature, conservation and restoration will evolve alongside changing ecosystems, and it is likely that our present beliefs require significant adjustment…Retaining the somewhat static view of ecosystems as particular assemblages in particular places will become increasingly unrealistic and is likely to shackle conservation and restoration efforts to ever more unrealistic expectations and objectives’ (Hobbs et al., 2009).

It’s important to remember that most of the ecosystem services that are provided by pristine ecosystems can be provided by novel ecosystems. So it’s not some harsh choice between purity or obliteration. And of course, it can be easily argued that all of our ecosystems, here in New Zealand especially, are novel in some way, shape or form. None of them are static or uninfluenced by humans.

The Ecological Society of America, easily the biggest and most influential ecological society in the world, recognised the changing perspectives represented by the concept of novel ecosystems last year by theming their entire conference around novel ecosystems.

I suggested to the organisers of last year’s New Zealand Ecological Society conference that we at least include a symposium on novel ecosystems in our programme this year, but was essentially rebuffed and told that the notion of novel ecosystems was not interesting to New Zealand ecologists. Our ecologists are instead still apparently on the restoration buzz from the 1980s. Frankly, I think we’ve got some real catching up to do on this one.*

Read the next instalment here. Or begin at the start of this series.

Featured image © Creative Commons.

*I offered the same suggestion to the organisers of this year’s Society for Conservation Biology Oceania Congress. Here no such objections were forthcoming and we ran a productive symposium.