Shades of grey

Spencer Shaw – Brush Turkey Enterprises
Shades of GreyOne of the greatest lessons I have learnt in the last few years is that nothing is clear cut, there is no black and white (just shades of grey) especially when it comes to all things natural, including weeds. As I have mentioned before there are many good reasons for not touching some weeds – they can provide very cost effective and necessary habitat for our fauna and can achieve the same environmental outcomes as natural ecosystems i.e. water quality improvements, carbon sequestration etc. Whole exotic ecosystems are developing that are species poor but are often the only habitat present in some areas. In many areas of the Blackall Range, SEQ, we can see forests of Camphor, Large-leaved Privet, Chinese elm and Broad-leaved pepper, with understoreys of Ochna, Small leaf Privet, Indian Hawthorn and vines that include Madeira, Morning Glory, Lantana and a host of exotic legumes. The question I am now going to put forward, is how can we use these weed ecosystems to further our objectives of ecological restoration and just what benefit can we put them to when it comes to the re-diversification of the landscape? First let’s make ourselves aware of the weeds that truly threaten existing native vegetation and concentrate our efforts on their control and elimination. Top of my list for forest destroyers with no redeeming features what so ever, are Cat’s Claw Creeper and then Madeira vine. These two vines can conquer a wide variety of ecosystems and undisturbed forest presents no barrier to them. Madeira is widely found throughout our region and once present on a water course can spread by the aerial tubers or potatoes, that it forms at leaf axils on the stem. It is shade tolerant and can grow high into the canopy of a tree where the weight of vine and tuber can break branches, snap tree crowns etc. Cat’s claw is just about to become a major problem in our area, if we are not vigilant in stamping out existing patches and stopping new colonies. It has all the tree strangling properties that Madeira vine has but it produces thousands of wind dispersed seeds that thrive in the low light conditions of intact forest and climb their way up trees and then swamp them with their profuse growth. Ok that’s the two “real baddies” out of the way (what was I saying about black and white?). What about some other weeds and how can we use them to restore ecosystems. Take Camphor laurel for example (please take it!) “How”, I hear you say, “do we work with them?” Well using the shades of grey analogy, I’ll present you with three shades of grey and how one weed species could be looked at differently in each situation. In a wet sclerophyll forest, Camphor laurel is a nasty weed. They can invade this type of natural ecosystem and eventually usurp the locals, eventually becoming a dominant tree, as seen in much of Nth NSW. In this case camphor can be rated as a weed of immense significance which needs serious control measures if biodiversity is not to be lost. However in our local rainforest, camphor laurels don’t really stand a chance. Low light levels or predation prevent camphor establishing in undisturbed rainforest. An example of this is their complete absence as a weed in forest remnants such as Mary Cairncross. In this case Camphor is not a weed because it doesn’t have the goods to cut it in the competitive world of rainforest plants. Our third example of Camphor Laurels is where we find the majority of them in our area. It is in heavily degraded landscapes that have been cleared of most, if not all, of their native forests. Here we see the Camphor (and Large-leaved privet) as an opportunistic pioneer species that has popped up along creek banks and along fence lines and is the only tree cover linking isolated remnant vegetation. In this case the presence of species such as Camphor can be used to our advantage in a very cost effective way. Our local rainforest plants have a nigh on impossible chance of germinating and growing in the competitive environments that our exotic grasslands present, but they can grow in the shade of camphor and privet (given that there is remaining native vegetation nearby to act as a seed source). In this case it is perhaps a better use of our time and resources that we look at how to increase the growth of these native plants so that they out compete their “exotic nurse crop” through strategic pruning and removal of exotics directly competing with the natives. So here’s the crunch. When we look at these areas solely as pest problems to be eliminated, we could blinker ourselves to their positive environmental values, which can be at great cost to local biodiversity and at great financial cost to ourselves. Planting trees is a necessary part of the works we can undertake but is also horrendously expensive for the scale of ecological restoration we need to be undertaking. Surprisingly, looking at how we can use weeds to create favourable conditions for the regeneration of our native vegetation could well be the next phase in major ecological restoration. Throwing Blackbean seeds into a patch of privet, weeding around native seedlings or planting a strangler fig in a weed tree may not be the answer for all patches of weeds but it’s a very cost effective, if somewhat slow method of doing something very positive with that patch of weed trees you just don’t have the resources to tackle yet. Let’s just remember that most of the other animals that live upon this planet don’t see in colour. They don’t pick native from exotic, they just see it all in shades of grey.