Tuesday, July 30, 2013

Sandalwood: Part 1

Santalum spicatum, Echuca (northern Victoria) demonstration site, October 2011
"Climate change is a game changer. We can no longer just conserve bushland, we need to imagine and construct new landscapes, with new farming systems, in which perennial native vegetation plays a strategic, structural role." (Andrew Campbell)
So, how to design systems that are productive and conserve biodiversity? In 2011, my partner and I were asking ourselves this question when were thinking about what to do with a 1 ha block on the Peninsula property that was originally planted with eucalypts and acacias (indigenous and non-indigenous) for timber.

The trees were not suitable for timber because they hadn't been thinned or pruned to suit timber production. We considered leaving them in the ground as habitat for, among other animals, koalas and birds, and for the soil health benefits, but they were shading a domestic orchard, managed by my father, on the property. There are also other areas on the property already devoted to conservation (approximately 70% of the total area) thanks to the efforts of Mum and Dad.
Ben Boxshall, ecologist with Spicatum Resources, next to a 10-year-old S. spicatum at a demonstration site at Ko-warra Native Grasses, Echuca, October 2011

Then in 2011, we visited a demonstration sandalwood plantation at Echuca in Northern Victoria and started thinking about the possibilities of native sandalwood (Santalum spicatum), which is indigenous to WA.

Sandalwood is a hemi-parasite - it attaches its roots to nitrogen-fixing host species and extracts water and nutrients. Its primary use is as oil in the perfume industry, but the wood is also used for joss sticks and for carving. There is currently a world-wide shortage of sandalwood because Indian sandalwood (Santalum album) is severely depleted due mainly to unregulated harvest of wild stocks in India.

Plantation sandalwood is generally harvested at 20 years - the older, the wood the more valuable it is due to its higher oil content. In the short term, there is also the possibility of deriving some financial return from harvest of thinnings (from year ten onwards) and from the sale of the sandalwood nuts, which the tree produces from year 5 onwards.
Ben Boxshall, ecologist with Spicatum Resources, next to a 10-year-old S. spicatum at a demonstration site at Ko-warra Native Grasses, Echuca, October 2011

At Echuca, the host species for the S. spicatum is a diverse mix of native nitrogen-fixing host trees, including acacias (A. stenophylla, A. salicina, and A. acinacea). In the early days of S. spicatum cultivation in WA, growers were advised to establish sandalwood with only one host species, Acacia acuminata (common name - Acacia jam), which is endemic to Western Australia and common in the wheatbelt. However, more recent research has demonstrated that S. spicatum will recruit on a wide range of native nitrogen-fixing host species.

At the Echuca site, the sandalwood was direct sown at a rate of two sandalwood nuts per host seedling. I was pretty excited by the visit, and set about doing more research. By the end of 2011, after discussions with Dad, we had decided to replace the woodlot with a mixed-species stand of indigenous trees and shrubs supporting a main crop of S. Spicatum. The host species will remain on the block permanently while the S. spicatum will be harvested at between 15-20 yrs of age.

Ben Boxshall, an ecologist and S. spicatum expert came out to assess the block and provide advice on host species selection, planting density, and weed control. Some of the indigenous host and companion species that we plan to use are Black sheoak (Allocasuarina littoralis), Indigofera australis, Alyxia buxifolia, and Olearia argophylla.
Dusky antechinus (Antechinus sainsonii). Will our sandalwood lot provide hunting grounds for this little dude? Source: Alan Couch, Licensed under a Creative Commons Attribution 2. Generic Licence

Potential environmental benefits include increased plant and animal biodiversity from the mixed, multilayer, indigenous host-tree population. The mid-level indigenous host plants will attract insectivorous birds, and provide habitat and forage for our local reptiles and small ground-dwelling marsupials such as the dusky antechinus (Antechinus swainsonii). As some of the host species are flowering, the plantation may also assist in attracting native pollinators to the adjoining orchard.

So far, we have had the existing trees on the block taken down. Unfortunately, while much of the wood was taken for firewood or chipped, cost meant we couldn't have the stumps ground, so the block is littered with very, very large burn piles. Its taken us longer than anticpated to burn these, which has meant that we haven't been able to do an Autumn 2013 planting of the host species and sandalwood. We should be ready by Autumn 2014. Sadly, this winter, we've become the biggest polluters in our neighbourhood with our burns that go for weeks on end!
February 2013 - to the left of the fence is the block cleared for S. spicatum; to the right, a 15-year old planting of indigenous acacias. 

We have also had to control the regrowth from the felled trees. On Ben Boxshall's advice, we've been doing this by slashing the regrowth (with a hard-bladed whipper snipper), then spraying with glyphosate at relatively high concentration (backpack sprayer). Once won't be enough judging from the regrowth coming back after our first pass.
 Wood pile after clearing of block destined for sandalwood, July 2013
 Wood piles after clearing of block destined for sandalwood, July 2013

Because I'm also interested in soil carbon and soil health, we are using this planned planting to participate in a soil health project run by the Westernport Catchment Landcare Network. It has the rather unwieldy name of 'Healthy Soils – Linking Soil Carbon and Soil Acidification with Farm Management Practices'. As part of this project soil on the block has been tested for carbon levels, as well as other nutrients (i.e. phosophorous, nitrogen, potassium, magnesium and calcium). I plan to write more on our particpation in this project in the next post on our Sandalwood journey - stay tuned.