Friday, January 6, 2012

I have an affection for weeds, gritty little survivors who set up life anywhere. Discriminated against but tough. The heroic underdogs. I like finding life in the most unexpected places and that is often a weed. After all our magnificent eucalypts were once weeds living on the edge of a Gondwanan forest. (It took me time to digest that when I first read it. But this affection can be pushed too far and Emma Marris does that in her Rambunctious Garden. Let’s re-evaluate them but it is bizarre to elevate them to the top of the ecological pyramid of good guys.

While reading Rambunctious Garden: Saving Nature in the Post-Wild World by Emma Marris, a little over 50% through (by this point there is lots of questions, lots of sledging but no answers, which I am looking forward to).

Wednesday, January 4, 2012

Marris's Rambunctious Garden too rambunctious?

I am annoyed by Emma Marris’s Rambunctious Garden, but maybe in a good way. It has certainly given me a new interest in invasive weeds, and a readiness to think differently. But and there is a big but, she seems to be simply saying bad stuff happens. Species ranges grow and shrink and species do go extinct – the world is really just one big garden for people to do as they like in it. And if we lose a whole bunch of interesting endemic species with short-lived, quick growing, rapidly seeding species who put little effort into their offspring. 

It is the economist’s view of ecology – a licence for greed and carelessness. Yes change happens but the rate of change in the past 200 years and especially the last 50 years is unprecedented. Ecosystems that have existed for 100s of years, 1000s of years (and that’s a lot of time in a world that marks itself as some 2000 years old), 100,000 of years, even millions of years, ecosystems that have co-evolved over many lifetimes are being destroyed in less than one. Yet she takes time out of the equation. Her position as an ecologist seems perverse. Yes climate change is changing the paradigm and we need to do some rethinking about what we consider "nature" and "wilderness'. Let's not throw the baby out with the bathwater. 

Is it important that the number of species on some islands are increasing though that is as the expense of the biodiversity of the world? Is that not obvious? Yes it is good to challenge prevailing wisdom, but what is she offering in its place? She seems to be picking around the margins, finding the exceptions, not the principles. The quality of the writing is disappointing for such a bold thesis. She is using language frequently to deliberately stretching the argument. She has eradicated time and the rate of change from her argument. Wow. Yes things have always changed chronologically and spatially but it is the rate of change that is a concern, a rate of change generated by the expansion of technology.

Maybe I have yet to read far enough. I am only 48% into the book (according the bar at the bottom of my kindle screen.) I look forward to writing again when I have finished the book.             

Davis has Oz wrong

In response to Marris citing it, I am now reading Mark A Davis “Researching Invasive Species 50 Years After Elton”. Davis is saying specifically in the case of Australia that: In Australia, non-native species have been reported to have contributed to the extinctions of some native mammals (see Finlayson 1961; Kinnear et al. 1998). However, the fact that declines in native species typically began decades before the introductions of species such as cats and foxes (often reputed to be the causes of extinctions), and the fact that species introductions are usually associated with other types of anthropogenic change that are believed to have contribute to the declines (for example land use change), it is difficult to ascribe extinctions of Australian mammals exclusively to no-native species (Abbott 2002; McKenzie et al. 2007.

Well that doesn’t accord with my understanding. Cats arrived with the First Fleet – the first settlement of Australia, as did cattle, which also soon ran wild. So I am not sure how “declines in native species typically began decades before the introductions” could work. In Australia’s case the introduction of species came early and non-native species spread quickly. We have seen waves of extinction in mammals since the arrival of Europeans – the latest of which is going on in the north at the moment with the disappearance of the bilby and other like sized animals.

A lot hangs on the word exclusively. Define it narrowly and  anything can be justified. Little if anything has a singular cause. The smaller mammals were not just killed by cats but had their habitats destroyed as farmers cleared bush litter, and the ground hardened by the hooves of introduced cattle. (Are cattle a land-use change or an invasive species?)