Sphagnum Moss - Sustainable Use and Management

Background

Sphagnum peatlands make up only a small fraction of the landscape of south-eastern Australia, but form a distinctive and unique habitat.  These communities 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 below the live Sphagnum. The high water table 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.

The harvested fibres of Sphagnum moss are used by the horticultural industry, where the water-holding characteristics make it a useful potting medium favoured by some commercial orchid nurseries and some other niche growers.  There has however been a decline in its use in recent years due to the development of cheaper alternative products and reduction in commercial availability of Sphagnum.

All Sphagnum harvesting in Australia takes place from natural (i.e. wild) populations, with the species S. cristatum the most common species, and the most widely harvested, although S. australe and S. subsecundum are also occasionally harvested.

Distribution

Sphagnum peatlands occur in Tasmania, 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 total area of Sphagnum peatlands in Tasmania is approximately 5200 ha (or 0.006%). Within Australia  as a whole the total amount of Sphagnum moss is very small compared to South America, New Zealand  and many European countries.

Protection and management

As of the beginning of 2009 the ecological community Alpine Sphagnum Bogs and Associated Fens has been nationally protected with a listing of Endangered under the Environment Protection and Biodiversity Conservation Act 1999. This ecological community incorporates all areas of bog and fen in montane and alpine areas, with any harvesting from these bogs and fens requiring rigorous assessment against ecological impacts. There is currently no legal harvesting from these communities.

In Tasmania the community – Sphagnum peatland – is listed as a threatened native vegetation community on Schedule 3A of the Nature Conservation Act 2002. This incorporates all Sphagnum communities in Tasmania including the lowland occurrences.  Subsequently there are no longer any licenced/legal harvesting operations of Sphagnum on publicly managed lands within Tasmania.  

There remains some limited legal commercial harvest from private land within Tasmania, where Sphagnum may be legally harvested if the intent is not to clear the vegetation or substantially change the ecology of the community. If harvesting operations occur on private land 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. In New South Wales all Sphagnum is protected under the Threatened Species Conservation Act 1995, as a component of the broader endangered ecological community, Montane peatlands and swamps of the New England Tableland, NSW North Coast, Sydney Basin, South East Corner, South Eastern Highlands and Australian Alps Bioregions.

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 harvesting

Traditionally harvesting 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.

In Tasmania and Australia as a whole harvesting has historically only been 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 growth

To 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.

Harvesting and management

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 that 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.

Code of Practice for Sphagnum Moss Harvesting

Harvesting

Sphagnum moss harvesting should not be carried out in the following:

1. Alpine and sub-alpine sites (i.e. sites with a minimum average January temperature of 10^oC or less), These communities are nationally protected.
2. 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.
3. Small Sphagnum peatlands (sites less than 20 ha).
4. Sites with a fluctuating watertable.

Management Prescriptions

Where harvesting takes place, the impacts on a site can be minimised by:

1. Retaining shrubs.
2. Retaining approximately 30% Sphagnum moss cover and spreading loose moss tendrils on any bare patches.
3. Avoiding the use of machinery that cuts up bog surfaces.
4. Leaving an even surface so that all remaining Sphagnum is close to the watertable.
5. Allowing about 5 - 10 years regeneration before reharvesting.
6. Limiting roading and drainage works in the catchment above and surrounding Sphagnum peatlands.