This is a difficult topic to discuss as the answer to the question "What to do about weeds?" is far from straightforward. And because the answer is complex, there is a range of, often strongly held, views.
The mainstream restoration view
Many people, if not most, working in ecological restoration view weeds as detrimental. I guess you can call this the mainstream view. Weeds need to be eradictated to improve ecosystem function, habitat integrity and ultimately support biodiversity. Weeds, then are an important element in the processes of land degradation. In fact, some ecologists see weeds as the number one threat to biodiversity.
Others such as Tao Orion (author of Beyond the War on Invasive Species A Permaculture Approach to Ecosystem Restoration) and Fred Pearce (author of The New Wild: Why Invasive Species will be Nature's Salvation) see it differently. Orion bases her thinking on the understanding that every species in an ecosystem, both native and otherwise, is part of complex ecological processes. She maintains that weeds have their place and doubles down on the sheer volume of herbicides used in ecological restoration work to keep these weeds in check. Orion admits that while the presence of invasive species is not ideal, she wonders that instead of reflexively labelling them as bad and using large amounts of herbicides to control them, weeds can be seen as serving important ecological roles in ecosystems. These include providing nectar for pollinators and shelter for birds, frogs and insects.
Pearce takes a different tack. He argues that invasive species, such as weeds, are unfairly demonised and does not reflect the reality of the new world we live in. Most ecosystems are now what he refers to as 'novel ecosystems', which are typically a mixture of native and exotic organisms. In his view, there is no going back to imagined pristine ecosysytems comprised solely of local native plants and animals. As Pearce puts it "nature never goes back; it always moves on. Alien species, the vagabonds, are the pioneers and colonists in this constant renewal". In light of this, he stresses we need to recognise the 'new wild' where ecosystems are composed of native and novel organisms. Then he goes further to argue that we need to lose our dread of weeds etc and conservationists need to stop spending so much effort "backing loser species - the endangered and reclusive". Instead we must back winners so that the new wild will prosper. Taking this to its logical end it seems koalas and quolls are on the short list to be dumped in the ecological dustbin of history but, hey, bring on the feral cats.
So who is right?
The mainstream emphasis in ecological restoration upon weed removal, particularly those that are highly invasive such as Madiera Vine, is valid. To let these species run rampant would simplify ecosystems with accompanying declines in biodiversity. To use a very simple example, removing Madiera Vine can save trees that are or will provide important nesting hollows for all manner of native mammals and birds. This emphasis upon weed removal, while a lot of work, resonates to those of us working on the ground. However, the alternate views offered above have some valid points worth pondering. Yes there is no going back to pristine and weedless ecosystems, and yes weeds can provide ecosystem functions and habitat opportunities for our native fauna. Lantana's role in protecting small bird species and providing nesting habitat is one such example. Furthermore, Pearce has a valid point that we need to recognise there is a new wild.
But, how far do we takes these arguments? Pearce's logic, in particular, looks reasoned and neat on paper. It is hard to refute his line of reasoning. After all, there is a clear linking of arguments to get him to the point that he suggests we stop backing loser species and start picking winner species, including weeds. But yet the endpoint of his reasoning makes us flinch because the implications are so dire. Indeed, a closer look at Pearce's argument reveals an approach to wildlife conservation where success is seen as essentially backing the right horse, so to speak, but with an endpoint of a lonelier, barren world absent of much of our iconic wildlife. This is where ideas look great on paper but sell us short in the hands on work of wildlife conservation. After all, the Koala probably falls into his loser species category, but who in all good conscience could give up that fight?
We said at the top of the page that the question "What to do about weeds?" is far from straightforward. However, the above discussion does show the importance of considering the different viewpoints and using these considerations to inform what we do on the ground where it really matters. So when approaching the weed issue we try not to default to the weed is always bad position. Instead, keeping people like Orion and Pearce in mind, we ask questions about whether the weed has some value in a particular instance and whether removal of the weed is going to be ecologically detrimental in some way. Essentially, our perspective is that decisions around weeds depend on the weed and the context. There is a world of difference between the impact of Cobblers Pegs and Cats Claw Vine. The latter must go as it is highly destructive, particularly in riparian zones. In relation to context, the presence of Lantana under say, Flooded Gums (with associated Bell Miner issues) is far different to Lantana under say, Angophoras. In the former, we would remove it. In the latter, it may be more harmful to rip it out with associated loss of habitat for small bird species. In this instance we remove the weed very gradually.
With this in mind, we have identified weeds that must go due to their detrimental ecological impacts (high priority for removal) and those that are more benign ecologically and are, consequently, a lower priority for removal. Please see our Weed Triage page for more information.