Fig 1: Trees and turf: a classically soil-compacted
horticultural environment – a kick in the guts of
the tree. The rhizosphere or soil/root interface
(the plant-stomach-lining) is the place where the
tree meets soil-life and exchanges plant sugars for
nutrients. Image: Cassian Humphreys
Cassian Humphreys looks to 2030 and beyond.
For most of us ‘organic’ has become more of a human buzzword than a descriptor for nature and natural process. Correctly used, the word relates to the nutrient-cycle and the passage of inorganic elements, as nutrients harvested from the atmosphere, that move or get synthesised into the bodies of plants, thus making those elements organic (a bio-element), and available to us.
Fig 2: Planting vegetative buffer zones on the edge of trees reduces stress load. Image: Cassian Humphreys
Plants are at the forefront of the nutrient-cycle which supports all bodies. Though there are numerous nutrient cycles, carbon – the building block of physicality, transitioned from inorganic to organic by photosynthesis – is the most obvious one.
Fig 3: Based on the propensity of soil compaction in turf, and for associate microbiology in gardens, the use of perennial ground covers is significantly better for trees than lawns. Image: Cassian Humphreys
Plants link the atmosphere and the rhizosphere via their bodies. As Shigo told us, they are the living pumps – the generators that move life on earth. All they need to live long is light sufficient to their species, air, water, and bioactive-carbon. When we take away or tamper with any of those foundation needs, we literally kick them in the guts. When it comes to nutrient absorption, the rhizosphere, and our stomach lining, we share parallels. To support trees the way nature intended we need aerated soils, nutrient beds and plant systems to the dripline as a minimum. This protects and nurtures the structural root zone and the tree protection zone in ways arboriculturists fantasise about.
Fig 4: Whereas young trees may endure the highly bacterial turf environment in the short term, in the long term, trees live short lifespans because of fungi deficient soils and a lack of mycorrhizae. Image: Cassin Humphreys
In conclusion
The backbone of this article is a rerun, far less the original chunk of science and references, but equally solid on the reason.
At the time I wrote the original I admit I was a bit pumped up with the story that followed on from Covid time, so there may have been some of my story caught up in that narrative. Still, as a piece, it was, and is, useful to highlight the reason why we arboriculturists need to be creating cold-processed, top-end mulches and composts.
Fig 5: Roundabouts surrounded by bitumen and the development process are usually highly biologically-desertified. Perennial plant associates – and the microbiology that accompanies them – make all the difference for trees. In rare cases below-ground resources (ie: old creek systems – Ficus and Creek Street in Brisbane City, spring to mind) are accidentally sustained during development, resources that retain air, compost and water below bituminised surfaces. This demonstrates what can be achieved in association with the engineers at planning stage with New Earth ventures in mind. Image: Cassian Humphreys
I encourage you to re-read Land Care via Vegetation Management Part 1 in the June/July 2022 issue of The Australian Arbor Age. Part 2 was an introduction to the concept of Naturaculture and was Prime Creative Media’s first article from me: Soldiery, Adventure Riding and Arboriculture in the December/January 2023 issue.
Fig 6 (above): A traffic island I restored from desertification to a de-compacted, species-diverse understory. The full restoration process features in the Heart of Arboriculture in AAA Oct/Nov 2021. Image: Cassian HumphreysFig 7: The rainforest remnant at Mary Cairn-cross Scenic Reserve in Queensland is an interesting study relating to the nutrient cycle. The floor of this forest is kept clear of leaf litter by the Giant Earthworm (1m-3m long, 2cm-3cm thick). A number of species are found throughout Australia’s hinterland ranges, and these remarkable creatures clear the whole forest floor of leaf litter and small twigs, dragging the shed organic matter into their tunnels. The important impact this organism has is in the multiple tunnels it creates. Earthworms generally deposit their castings above ground, but not so the Giant Earthworm. It deposits its castings below ground. The Trapdoor spider, freshwater crayfish, and a host of other organisms help keep rainforest soils friable via their tunnels. Barring organisms displaced by us, there are few natural organisms that are counter-arboriculture – except modern humans (particularly engineers). Image: Cassian HumphreysFig 8 (above): We can see the fluffy soil deposited at the site of this excavation. Whether created by a Giant Earthworm, Funnelweb spider, or freshwater crayfish, the fissures help keep the soil friable. Image: Cassian HumphreysFig 10 (above): The microbiology associated with the forest is integral to the nutrient cycle that processes timber into humus. Fungi are as essential for processing wood (lignin and cellulose) as they are in supporting woody plants to absorb nutrients from the rhizosphere. In live trees the fungi enable solid trunks to lose static ballast by decaying heartwood, The fungi and the decay process – involving brown rot, soft rot and white-rot wood decay – are intrinsic to nature and the ecosystem. Image: Cassian Humphreys
Those past narratives explored my prediction that it will be our profession which will have the opportunity to unite the allied land-management stakeholders because of the need for bio-active carbon resources – a compost product range I believe we should be responsible for producing and making money from – as well as developing the microbiological mind behind the service, something that can only broaden our integrity as arboriculturists. I likewise consider we are being naive as tree- or land-care professionals if we think we can sustain our families into the future by clearing vegetation into cooked stockpiles that do nothing to restore soil health or support the natural cycle of biology. There will come a time when land clearing will be a thing of the past, especially if we help write the future. I solemnly pray that mainstream arboricultural education takes on the Naturacultural or conservation arboriculture principles I live by.
Fig 11: This brown-rot decayed log with its cellulose long gone has become an above-ground resource for the occupation of feeder roots from neighbouring live Tallowwood gum trees. The log, now looking more like charcoal (natures bio-char) than timber, provides a network of oxygenated galleries for the essential associate microbiology and feeder roots. I have seen the same plant root occupancy with white-rot galleries in standing trees and cut palm logs where the above-ground log becomes an extension of the rhizosphere. Image: Cassian HumphreysFig 12: Ripped logs, cut longitudinally – with the grain – make the best interface between treated soils and turf. The raw, ripped, hardwood logs last a few years before becoming compost. These are easy to process, easy to install (they become glued to the soil by Glomalin) and easy to replace. Image: Cassian HumphreysFig 14: The traffic-island project nutrient bed,16.5m by 9.5m, roughly 155m2, was treated with approximately 910 fissures to de-compact and open up pathways for microbiological activity. Fissures ranged from 10cm diameter (done with an auger) to tube-stock size, with 290 young plants in the ground, capped with composted forest-blend mulch, log rounds (to act as maintenance pathways to prevent future compaction) and ripped-timber edging to interface with turf on the western side. Image: Cassian Humphreys
My next evolutionary step is to return to Britain for my first book launch and to partner with a historic estate to co-create my first Conservation Arboretum, and to co-fund such a venture via delivering Naturaculture-based education. In time I will be looking to achieve the same Downunder, hopefully in Canberra. Time will tell.
Fig 15: I use the same strategy of soil cultivation for vegetable gardens, creating fissures, trenches, or simply single digging: blended compost (90 per cent) anbd charcoal/sand (10 per cent), depending on resource availability. In the case of this salad/vegetable garden I treated with fissures under the sleeper pathways to support root generation under the paths. This maximised surface area/water retention, I utilised 1.5m of compost that I harvested straight off an old tree and leaf-litter-covered horse shed. Image: Cassian Humphreys
Finally
In closing, whether we create counter-arboriculture, non-sustainable tree culture, or we create conservation-arboriculture, we are still working with the same elemental resources of air, water, and carbon. We are still using manpower and a measure of machinery, though in the latter model I suggest we are working far more intelligently.
Fig 16: When I make reference to compost it is always cold-processed, nature’s way, not the human, heat-treated bacterial sludge we call compost. Here’s a good three cubic metres of nature’s chocolate-gold I harvested off the barn and incorporated into the vegetable garden. Image: Cassian Humphreys
