This is the final part of a four-part article by BEC member GEOFF DAWE, regenerator consultant for the Cumbebin Wetland in Byron Bay.

Part 4: Weed Succession and Replacement at Cumbebin

 

Banna Grass as Weed Inhibiter and Madeira Forces Focus on Soil

 

Weeds no longer exist when all plants are seen to be perfectly placed. The western mechanistic mind has little room for what is not readily observable.  Motivation for bush regeneration therefore, has largely come from empathising with the noticeable plight of threatened species, rather than the less obvious deterioration in soil.

 

Once the plight of soil is recognised, rampancy of plant growth, perhaps the main reason why particular plants are accorded weed status is seen as beneficial.  It is at this point that the bush regenerator (or agriculturalist) realises that a policy of fitting native plants and agricultural produce in with rampant plants has more beneficial consequences than one emphasising weed eradication.

 

Banna grass, because of its rapid growth requires regular input.  Natural regeneration among it is close to nil and this plant is perhaps the strongest reason why chemical free regeneration requires that native planting supplies a full canopy.

 

Planting of Natives

 

Banna grass has its limits with heavy shading.  Native trees are planted within it at approximately 2.7 spacings by searching among the Banna grass growth for areas where clumps have not tended to occur.  In those areas where to keep 2.7 spacings, Banna grass has to be removed, the Banna grass is cut as close to the ground as possible for a one metre diameter planting circle. 

 

This action is premeditated approximately one month ahead of planting time because cut clumps have little vitality, or die out completely with heavy shading by their neighbours. 

 

In common with all grasses, as the tops are cut, so roots die back in the soil to become about as long underground

as the plant’s above ground height.  A one month return after cutting, yields clumps perhaps just beginning to resprout but with roots of such small length, that the cut clump provides little resistance to a planting of native tree in its vicinity.

 

Maintenance

 

Canes growing alongside planting diameters are not removed but retained as both a grasses inhibitor and as protection for native seedlings.  Canes alongside trail areas or immediately on the edge of planting diameters are

cut quite short, but allowed greater length as one moves outward from planting diameters or trail areas.

 

This prevents long canes who gain their long length by leaning against their neighbours, from falling over onto native seedlings as soon as regenerators leave the project for the day.  Cut canes (as opposed to leafy tops) are

placed up in the Banna grass clump for drying.

 

Once the regenerative plot is underway, it will be noticed that Banna grass regularly trimmed to allow light to native seedlings, will produce non-sprouting leafy tops rather than canes that tend to sprout.  The leafy tops are easily cut with shears rather than a more fatiguing chopping action of canes with machete or whatever, and the tops can be thrown directly around native seedlings as a mulch. 

 

Regenerators find they are “killing three birds with the one stone”, keeping Banna grass trimmed to a height where it is able to do most of its work in holding out more “invasive” grasses but at the same time allowing light to natives, and mulching of the natives.

 

Banna grass as a regenerator

 

Long term bush regenerators will be familiar with the edge effect between stands of native bush (or even stands of exotics such as Camphor Laurel) and rampant plant growth.  There is often a lull in the rampancy at the outer edge of the canopy, and if Banna grass does take up residency, because of a strong shade intolerance, it tends to do so away from the canopy and therefore acts as a screen to exotic vines and shorter grasses. 

 

At Cumbebin, the area between the Melaleuca wetland and the Banna grass is one of the areas of greatest natural regeneration.  When it is considered that the northern sun sector with its rampant vines and grasses is the maximum expender of human physical effort, one is able to see Banna grass paradoxically as an inhibitor of weeds.

 

It is also important to notice that its clumping growth is a strong retainer of soil movement and that in watercourses it has the ability to hold banks with greater steadfastness than even the naturally occurring Lomandra species.  That is not an argument for BannaGrass retention, but simply for dispassionate attention to its superior surface soil holding abilities.

 

 Madeira Forces Focus on Soil

 

Vines, particularly Madeira and Cat’s Claw, present a particularly difficulty for chemical free bush regeneration in that they are not defeated by shade.

 

It is known that human labour to fine sift for Madeira corms in soil is appropriately rare or non-existent.  At Cumbebin Madeira outbreaks are isolated with dense foliage natives planted in their vicinity.  The vines are kept off the trees by simply snipping them close to the ground.  Labour to do this becomes less demanding the taller regenerative plants grow and the further vines have to climb to reach sunlight.

 

Long term solutions are connected to long term views.  It is reasonable to assume that dense Madeira growth facilitates soil change that allows an evolution to replacement species.

 

In post-industrial revolution communities whose major livelihood focus is sustainable agriculture, regular maintenance of native forest, may involve the harvest of Madeira corms for their use as soil tonic.  The energy stored in all bulb and corm plants is a large food supply that gives the plants a relative independence from soil. 

 

That food supply is concentrated organic matter.  Its potential for improving soil through its use as a liquid manure

for example, is unknown.  What is known is that specific soil micro flora and found often congregate around particular species. 

 

The search for subtropical plants who have similar soil life around their roots as Madeira, and who therefore may be appreciative of the soil improvement abilities of Madeira, has yet to be done. 

 

That is understandable.  Both chemical free bush regeneration, and its inseparable twin sustainable agriculture, are in their infancy.

 

 

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