Growing trees for threatened species – a longer term approach

Coinciding with threatened species day next month, the Crossing Land Education Centre is holding a free workshop on windbreak plantation design. The advertising material indicates  presentations are planned in the morning, including one  “. . . about the local koala population by Office of Environment and Hertiage (sic) scientist and local koala expert Chris Allen.” Accordingly attendees will be provided with lists “featuring fire retardant species and key koala species.”

I’m not sure why Chris Allen has been given the title of ‘scientist’, given a science degree is usually required. Similarly, Allen’s koala expertise would seem to be constrained to data on tree species koalas prefer in adjacent forests, where Forestry Corporation claim to be the tree growers.

However, if we leave aside the notion of fire retardant plants, everything burns if it’s hot enough. The question remains whether there is much point planting trees for koalas, if the soils cannot support their growth. The afternoon is devoted to planting a windbreak, although whether soil preparation has been a consideration is not clear.

wallace

Unlike koala surveys, that can provide instant gratification, an  alternative approach takes somewhat longer. Generally three years or so, employing a Wallace plough, pictured above, is required to adequately prepare the degraded soils for planting. There are several benefits from this longer term approach, including reduced compaction, increased aeration and biological activity. This particular unit has a seed box that could also be used to add other beneficial soil materials. The outcome, as indicated in the Equine permaculture graphic below, is an environment that encourages biological activity and deeper root development.

While this approach is similar to the deep ripping being trialled on the tablelands, there are significant differences. For example the Wallace plough is designed to ensure minimal surface disturbance. One off  deep ripping, without coulters, the serrated cutting discs at the front of the plough, rips grasses apart and tends to bring sub-soils to the top.

Another difference are the hydrological impacts, deep ripping across the contour, as employed on the tablelands, tends to increase the speed of water moving downslope and associated gully erosion. ‘ However, when  ‘keyline’ principles are employed, water is diverted along the slope, via the subsurface channels created by the plough and water is directed away from gullies.

Interestingly, John Champagne, Permaculture Designer and President of SCPA-South East Producers will also be giving a presentation, so perhaps other approaches may get a mention.

 

deep-ripping

 

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