A three part series by Geoff Dawe
Part 1: Philosophy
Chemical-free weed control at Cumbebin Wetland on the western edge of Byron Bay is based in the knowledge that soil organic matter levels (OML&Mac226;s) in western land use patterns, are in decline. The chemicalfree method aims to aid in the retention, or even increase of OML&Mac226;s and therefore is not separate from other rural land use activities, including agriculture.
Weed species currently dominate because soils are under threat. Nature is well aware, even if people are not, that what grows and lives upon the soil is secondary to the need to retain soil. Whilst our species, through ignorance, collapses soil health, weed species rush in to provide the biomass that provides the organic matter that healthy soil requires. Many native species are no longer able to optimally provide organic matter for organic-matter-starved soils and they have been replaced by exotic species better able to return biomass to soil (if for no other reason than they have volunteered for their position in place of natives). Weeds also shade and hold soil, soften heavy rains and feed many animals, all who manure, and some of whom are native. Weeds therefore have a part to play in land regeneration.
Social Perception of Weeds
Weeds themselves, in common with all land degradation, are created by an imbalance in social perception that can only be effectively cured from a rebalancing at the perception level. All parts of nature have both positive and negative effects, and the current debate on Camphor Laurel shows an awareness of these effects. The current balance of social perception is now shifting away from the view that things can be clearly differentiated into the good and the bad, i.e. things that deserve existence, and things that do not. The chemical-free regeneration technique at Cumbebin Wetland therefore incorporates a continual search for the usefulness of the various weed species, particularly as aids to the growth of native plants.
Weed Rampancy
Many weeds are despised because of their rapid growth. It is precisely this characteristic that makes them Since weeds are symptoms of land degradation, their proliferation is linked to the ignoring of land health by using technological inputs. important in regeneration. Western culture is experiencing a continuing reduction in OML&Mac226;s and a focus on soil can help in overcoming land degradation. It can be seen that greater rampancy of plant and animal life upon any area of soil is the means by which soil OML&Mac226;s most eficiently rise. Many of our rampant plants are weeds and this makes them provisioners of higher OML&Mac226;s.
Non-chemical Use
The issue of the non-use of chemicals does not concern itself primarily with the potential toxicity of chemicals, (although there is little doubt that this occurs). No pesticide has been proven safe and many have been withdrawn from sale when proven unsafe. The primary issue is technological dependence which brings about the consumption of products thought to be so necessary that there is a denial of side-effects, and the mind ceases the search for alternatives.
A further concern of using chemicals is that they are part of a technological armoury including artificial fertilisers and genetic engineering techniques that are able to support plant and animal growth arti• cially without the need (in the short term) to notice soil health. Soil OML&Mac226;s drop because production is able to occur without the necessity to completely return organic matter.
Since weeds are symptoms of land degradation, their proliferation is linked to the ignoring of land health by using technological inputs.
The chemical use which many bush regenerators see as part of the solution, can also be seen to be part of the problem.
Unless there is an attempt to highlight the need for experimentation with non-chemical control of weeds, and the finding of information associated with that, the ongoing soil and water degrading effects of land clearing and chemical use will have simply jumped from agriculture to bush regeneration.
What then is a chemical-free method of regaining native plant dominance without neutralising the regenerative ability of weeds?
Part 2: Strategy
Since weeds are co-regenerators, they are not considered to be part of the problem. Rather, the problem is the spaces between native trees, and a narrowed focus view that weeds are of little use.
Camphor Laurel for example, is not seen as an invasive alien, but as a source of organic matter that has potential among other things, for food production. Tweed Shire councillor, Henry James has said that Tweed Shire Council landscape workers notice no difference in the growth of trees from those mulched with Camphor Laurel chip and those mulched with the chip of other species.
In small area farm production where orchard trees are incrementally introduced, chipping can be bypassed with the use of a chainsaw that cuts camphors into carriable lengths that are then placed around orchard trees. Beetles and other small animals add manure in the reduction of logs to sawdust over an extended period. Camphor Laurel has a signi•cant ability to recycle potassium.
Native Tree Canopy
Weeds particularly in sun positions are extremely rampant, and so they need to be to protect soil. Chemical free weed control involves keeping weeds off natural regeneration trees and adding further trees in order to keep a native tree spacing of an arbitrary 2.7- 3.0 metres which is considered presently to be optimal in providing canopy cover. The Strategy is not focused in weed eradication. It is the native trees production of a shading canopy that primarily does that. Weeds in sun areas are cut or pruned away from native trees so that the energy of the weed is not eradicated, and the native seedling is selected above that of the weed.
There is an attempt to time the return so that tree seedlings are covered by weeds ideally no longer than a fortnight. A stake and fluorescent tape are extremely important because often trees can be lost among weeds. There is also an attempt to return as infrequently as possible, and freshly weeded covered trees do not appear to suffer knockback. During the recent drought, it appeared that the encroaching weed canopy may have given seedling trees an overall respite from the drying effects of no shade. Certainly a study on the survivability rates of trees devoid of surrounding vegetation and those growing within maintained weedscapes would tend to eliminate the potential for weed myths.
Seedbank removal not a priority
The attempt to remove seedbanks is regarded by this regeneration technique as ‘pissing against the wind’. Weeds serve as indicators that land use techniques have been poorly considered. The problem is not fixed by simply eradicating the weeds or neutralising seed dispersal but by considering better land use techniques and in so doing, weed proo•ng lands. Landowners should be aware that current conventional land use methods are involved in the process of ‘killing off what wants to grow, and trying to keep alive what wants to die’.
A closed canopy native tree area does not tend to harbour weeds. Pasture areas that are made more fertile, strengthen grasses to that they have greater ability to block out&Mac226; weeds naturally. Fertile pasture lands in these areas are more often than not the flatter areas. Grasses on hillslopes are often not enough vegetation, bare patches of soil emerge, and it is here that weed seed such as Groundsel, Mist & Croften weeds take hold to add more biomass than can be offered by grasses.
Hillslopes in these sub-tropical areas, need re-treeing to prevent weed incursion. Roadside verges, as demonstrated by the RTA can be thickly planted with suitable native vegetation to leave no niche areas for weeds.
In all of these areas there is no doubt that weed seed is on the ground, but if the land area is used correctly with regard to increasing organic matter levels (OML’s) the seed does not tend to germinate. The seed that is on the ground lies there as an indicator – a warning of deteriorating land use and movement against it, is in effect, a movement against Nature’s emergency response.
Easily Let Go of Principles
Nature appears to take delight in its insistence upon diversity to such an extent that it tends to create exceptions to all rules. Chemical free weed control is an evolving process involving observation and experimentation with every regenerator able to offer more constructive ways. Madeira vine for example presents a problem with the general principle that seed bank removal is not a priority. At the present moment we tree at close spacing with dense canopy shade loving trees on the perimeter of severe Madeira growth areas in the hope that future layered canopies may produce extremely low light levels that prevent Madeira germination. We have no idea whether this will work or not. In the meantime with new or minor infestations, corms and plants are removed according to conventional regeneration methods. there is also a tendency not to eradicate weeds, but since weed hatred appears to occupy some workers presently, there is not an insistence on cutting weeds rather than pulling them out. It is not definitive answers that are sought, but balance.
Letting go of eradication:
Noticing and using the Energy of Weeds
All weed species have a beauty as well as a difficulty, so does everything else on the Earth. Chemical-free bush regeneration involves going with the beauty of a weed so that it is not nullified, and using its difficulty to select in favour of native vegetation.
How that happens requires a focus in turn on particular weeds at Cumbebin.
Part 3: Weed Succession and replacement at Cumbebin
Chemical-free bush regeneration being particularly labour dependent, produces rapid recognition that human energy is most expended on many stemmed plants in any given area such as grasses, and is least expended on few stemmed plants in any given area such as trees. In other words, exotic trees are not as difficult to control as exotic grasses. As a consequence, weeds are farmed rather than removed, and there is the allowance of a weed succession where some weeds actually work to inhibit the energy of others:
Wild Tobacco (Castor Oil plant similar)
Not seen as a threat to native regeneration. In fact consideration is being given to broadcasting it among Lantana. Many species of native birds feed from it. It therefore aids native regeneration. It provides rapid soil shading and therefore helps to inhibit grasses. Maintenance requires that it not be dominated by other weeds such as Banna grass or Morning Glory, so these weeds are cut from it.
Wild Tobacco has a relatively short life span and tends to die of its own accord after approximately 3 years and certainly after heavy shading by natives. In common with all plants that die, it leaves decayed roots in the ground which become channels for the freer passage of air through soil and therefore increases soil microflora and fauna. In effect it acts as a digger of the soil. One could envisage that in a society that looks more toward the long term, garden beds and orchards would be premeditated years ahead of their use and sowed with Wild Tobacco (and perhaps other plants) in order that the era of the turning of the soil practised by humans for so long comes to a close.
Certainly in bush regeneration the deliberate removal of Wild Tobacco is more an act of destruction of the expansion of native habitat than an aid. Its difficulty is only its exoticness and that is overcome easily by natural regeneration occurring automatically, or the planting of native trees at closed canopy spacings in its vicinity. Branches of Wild Tobacco are cut out of the way of native trees, and that organic matter aids native growth.
Lantana
An easily controlled weed that works to improve soil friability, and to provide shade to soil overexposed to sun through tree removal. In reafforestation areas it is not removed but pruned as a bush or hedge. It is ironic that it was originally brought to Australia as a hedge plant and that chemical free bush regeneration over 200 years later sees its usefulness as a hedge plant. In areas of intense Lantana growth, combined access trails and planting and/or native regeneration areas are cut 1 metre wide. Planting distances are arbitrary. In areas where natural regeneration is strong or is expected, metre wide swarths are kept clear whilst watching for native seedlings.
Hedges are maintained with standard hedge shears or with a sharp machete or sage grass knife, but initial cutting of metre wide planting/walking/natural regeneration areas is done with machete and loppers. The dif•culty of Lantana is that initial cutting takes quite some time with canes being up to 50 mm thick, and cut material needs to be cut into smaller lengths in order that it may ‘lay down’ in slashed areas. But its difficulty, as I promised in ‘Noticing and Using the Energy of Weeds’(Part 1), is its weakness when it comes to selecting for the growth of natives above that of the weed. Because thick canes take a comparatively long time to grow, a months growth, about the space of time before a return visit, yields comparatively thin branches which are quickly trimmed.
Lantana maintenance is very easy when compared to its initial cutting. Hedges can be cut shorter in winter whilst native seedlings require more sun, or be left grow longer in summer to provide greater shade for optimum growth of native seedlings.
In areas where native trees already have some maturity and Lantana has draped itself over the trees, enough vines are cut at ground level to ensure tree survival, but often many canes are left to provide further shade to soil and to prevent secondary weed infestation by difficult to control grasses. In this way Lantana acts as a partial screen and therefore more obviously aids the work of bush regeneration.
Lantana diminishes in energy as shade from natives intensifies. Eventually, it has little ‘will’ to remain and eradication becomes unnecessary.
In fact under a closing canopy situation, the reduced vigour of Lantana allows it to occupy a lower storey position where it is able to continue its work of provisioning animal life and soil, without threat to a dominating native system.