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| Sphagnum Moss - Sustainable Use and Management
Background
Distribution
Conservation and management
Sphagnum moss harvesting
Sphagnum moss growth
Harvesting and management
Code of practice for Sphagnum Moss harvesting
Sphagnum peatlands make up only a small fraction of the landscape of south-eastern Australia, but form a distinctive and unique habitat.
Sphagnum moss is extensively used by the horticultural industry. Its water-holding capacity makes it a useful potting medium, favoured by orchid growers and often used to wrap rose and fruit tree rootstock for transportation. At present all Sphagnum harvesting in Australia takes place from natural (i.e. wild) populations. However, growth trials of Sphagnum moss in glasshouses have begun in New Zealand, which may eventually lead to commercial growing.
S. cristatum is the most common species in Australia, and the most widely harvested, although S. australe and S. subsecundum are also regularly harvested.
Sphagnum peatlands usually form in sites of relatively high rainfall and low evaporation, in areas never or rarely subject to drought, and in infertile, anaerobic soils (lacking oxygen). They commonly occur in river valleys, beside lakes and streams or on sandstone shelves, where drainage is hindered. Acidity created by Sphagnum deters bacteria and fungi which would otherwise decompose the dead material, allowing peat to build up. The high watertable and mossy vegetation of Sphagnum peatlands result in a fragile ecosystem sensitive to disturbance. Current threats to the long-term survival of Sphagnum peatlands include draining for agriculture, frequent burning, peat mining and unsustainable moss harvesting.
In Tasmania, Victoria and New South Wales, Sphagnum moss tends to die if it dries out in summer suggesting that Sphagnum peatlands in south-eastern Australia may be near their climatic limits. If so, global warming is likely to reduce their chances of long-term survival.
Sphagnum peatlands occur in New South Wales, the Australian Capital Territory and Victoria, usually between 300 and 1500 m elevation. Tasmania's largest area of Sphagnum lies between 600 m and 1360 m.
The amount of Sphagnum moss in Australia is very small, compared to Northern Hemisphere countries, South America and New Zealand. For example, the total area of Sphagnum peatlands in Tasmania is approximately 1300 ha (or 0.0015%). Most of this resource (>90%) lies within State Reserves and is unavailable for harvesting. This has put pressure on remaining peatlands.
When considering management of Sphagnum peatlands it is essential that the whole catchment area in which they occur is managed appropriately. Activities higher in the catchment, such as logging, roading and farming, can alter water quality by adding sediments and nutrients, thereby altering peatland ecology.
In Tasmania at present there are no controls on moss harvested for the domestic market on private land. However, if harvesting operations occur in peatlands containing rare or threatened species, a permit is required under the Threatened Species Protection Act 1995. In Victoria, Sphagnum peatlands are listed under the Flora and Fauna Guarantee Act 1988, and a permit is required to harvest Sphagnum moss. In New South Wales all Sphagnum species are listed as protected native plants under the National Parks & Wildlife Act 1974, which means a permit is required for harvesting. In the A.C.T. a licence is required to harvest Sphagnum under the Nature Conservation Act 1980.
Sphagnum moss exports from Australia are subject to the Wildlife Protection (Regulation of Exports and Imports) Act 1982 and require a licence from Environment Australia.
Sphagnum moss harvestingHarvesting is usually carried out by hand, with other vegetation (usually rushes) cleared with a scrub cutter and rake. At some Tasmanian sites, drains have been built around the edge of the peatland to allow easier extraction, but this may cause long-term damage. Harvested moss is put into nylon wool bales which weigh between 100 and 120 kg when wet. These bales are carried out by either - dragging by hand, using tramways, three-wheeled motorcycles and bulldozers with varying degrees of damage to the site.
Over the last decade the Sphagnum harvesting industry has expanded significantly, with around 15 tonnes extracted in Tasmania and a minor amount harvested in Victoria and New South Wales. Harvesting is carried out on an extremely small scale when compared to commercial operations in other countries. However, the number and size of Australian peatlands mean that the impacts of moss harvesting have been relatively high on this fragile ecosystem.
Sphagnum moss growthTo assess the sustainability of harvesting, several sites of varying conditions were selected in Tasmanian and Victorian peatlands and the growth rate of S. cristatum measured. The growth rate varied in Tasmania from 0.4 cm/year at a high altitude site (950 m) at Mt Field to 4.2 cm/year at a sheltered, highly productive site at 530 m in central Tasmania. In Victoria, the growth rate at the high altitude (1380 m) site at Baw Baw was 1.9 cm/year and 5.2 cm/year at the sheltered site at 900 m in the Central Highlands. Moss growth declines as altitude increases. In Tasmania, Sphagnum moss grew more than ten times as quickly in sheltered sites than higher sites. In Victoria, it grew more than twice as fast in sheltered sites.
A shade cover of trees and shrubs of between 20% - 40% increases growth rates. Some shading protects Sphagnum from drying out in summer while a lack of shade may allow other plants to outcompete Sphagnum. Shrubs are often cut to enable easier harvesting.
Most moss harvesting sites show signs of degradation, including altered drainage and a decline in plant growth. Greatest deterioration occurs where drains are excavated. The intensity of moss harvesting at a site affects its overall recovery and regeneration capacity.
Sphagnum regeneration is slow, or sometimes absent, where a bare peat surface is left after harvesting. This may promote the growth of other plants (such as rushes and sedges) at these sites. Retaining at least 30% of the moss cover results in a faster recovery than leaving a bare peat surface.
Fertiliser is sometimes used after harvesting to promote moss growth, however further work is required on its effects. The use of fertiliser may encourage weeds which hinder moss growth rates, cause burning of peat surfaces and result in straggly, poor quality moss strands. If used at all, the fertiliser should be a low grade, organic variety.
The use of machinery cuts up bog surfaces, and creates an uneven surface. This results in water conditions that are then too dry or too wet for Sphagnum growth. Disruption by machinery also allows the movement of sediments and nutrients both into and out of the peatland. Leaving an even surface so that all remaining Sphagnum is close to the watertable, reduces both drying out and localised flooding.
The most damaging moss harvesting is done by harvesters operating (sometimes illegally) on a once-off basis. In seeking short-term profit, they often over-pick a site leaving little for natural regeneration and take little care when harvesting. Illegal harvesting is an increasing problem.
Questions raised in developing guidelines for long-term sustainable Sphagnum moss harvesting in
Australia include: - Is there adequate information for sustainable management?
- What is the distribution of Sphagnum peatlands in Australia?
- How can harvesting impacts on recovery be minimised?
- How does harvesting affect rare and threatened species?
- How can Sphagnum moss best be regenerated?
Sphagnum Moss HarvestingHarvesting
Sphagnum moss harvesting should not be carried out in the following: - Alpine and sub-alpine sites (i.e. sites with a minimum average January temperature of 10oC or less).
- Sites that :
- are on basalt;
- are on limestone (in sinkholes);
- contain rare or threatened plant/animal species or communities;
- are floating (i.e. aquatic) moss beds;
- rainforest-Sphagnum peatlands;
- that are undisturbed sites.
- Small Sphagnum peatlands (sites less than 20 ha).
- Sites with a fluctuating watertable.
Management Prescriptions
Where harvesting takes place, the impacts on a site can be minimised by: - Retaining shrubs.
- Retaining approximately 30% Sphagnum moss cover and spreading loose moss tendrils on any bare patches.
- Avoiding the use of machinery that cuts up bog surfaces.
- Leaving an even surface so that all remaining Sphagnum is close to the watertable.
- Allowing about 5 - 10 years regeneration before reharvesting.
- Limiting roading and drainage works in the catchment above and surrounding Sphagnum peatlands.
Reservation of Sphagnum Peatlands
When considering reservation of Sphagnum peatlands priority should be given to pristine sites. Reserves also need to be of an adequate size and number to allow for natural changes, and to conserve different types of peatlands.
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