This section explores the carbon sequestration options to the South West region. Priority has been given to options addressing other NRM benefits such as habitat protection and connectivity, water quality and soil stabilisation. Modelling for determining carbon sequestration priorities has been done by Wimmera CMA, in partnership with the Corangamite and Glenelg-Hopkins CMAs, and can be found within the respective regional strategies at http://www.swclimatechange.com.au/cb_pages/regional_planning.php
Enhancing native vegetation through natural regeneration is a recognised method for promoting carbon sequestration under the Australian Government’s Emissions Reduction Fund. It is often the most efficient and cost effective, especially when compared to standard revegetation practices and other carbon sequestration activities. Natural regeneration can be encouraged through reducing current threatening processes such as over grazing and environmental weeds, and/or increasing processes such as additional plantings and restoring natural fire or flooding regimes.
Revegetation is another recognised method of encouraging carbon sequestration through the Australian Government’s ERF. Revegetation, through biodiverse plantings, has many other NRM benefits, and is one of the most effective ways to make many of the region’s landscapes more resilient to climate change. Mainly through buffering existing remnants, protecting riparian areas and reducing existing threatening processes such as soil erosion.
Revegetation can also increase connectivity i.e. buffers, corridors, stepping stones, between existing areas of fauna habitat, and create refugia. This will be important as the region’s climate changes and some fauna in existing locations need to move to more favourable areas.
Farm forestry is another form to carbon sequestration activity already being implemented in many parts of the region. In addition carbon sequestration, farm forestry provides a future source of timber. This places less pressure on existing remnant areas of vegetation on roadsides and private land as firewood sources. Farm forestry can also act as a buffer to fragmented vegetation and a way to broaden the appeal of biodiverse plantations on private land.
Saltmarsh, mangroves, and seagrass meadows are collectively known as “Blue Carbon” habitats. Blue carbon habitats have recently been identified as one of the most effective carbon sinks on the planet. Such habitats can bury carbon at a rate 35-57 times faster than tropical rainforests and can store carbon for thousands of years. These features make vegetated coastal habitats ideal candidates for carbon offset programs and nature-based climate mitigation initiatives. Other benefits of blue carbon habitats include;
- They can sequester nearly equivalent quantities of organic carbon as their terrestrial counterparts, in spite of their comparatively limited biomass (0.05% of terrestrial plant biomass).
- They can store organic carbon at almost 40 times the rate of terrestrial systems, largely due to their relatively anaerobic soils preventing organic carbon remineralisation and therefore promoting long-term sequestration.
- Carbon in blue carbon habitats may be stored for centuries to millennia.
- Blue carbon habitats can both produce and store their own carbon, but also trap carbon produced from other locations.
- Their ability to trap particles and suspended sediment means that they may appropriate large quantities of carbon that originates from adjacent habitats, both terrestrial and marine. This is of particular importance in the region where a majority of waterways filter through coastal saltmarsh before entering the sea.
Soil carbon is essential for soil health. It assists in soil structure and provides food for soil microbes that in turn benefits plants and helps regulate nutrient cycling. The amount of soil carbon varies across the south-westgion with peat soils in the region’s southwest at levels greater than 10% through to areas with high cultivation histories where the carbon level is typically less than 1%. This variation is a result of many factors, namely:
- Soil and vegetation type, which determines the carbon-holding capacity
- Climate, especially rainfall and temperature which determine the rate of decomposition
- Land management practices, both current and historic