What’s possible, what’s optimal?
The Carbon Farming Initiative (CFI) is a carbon offset scheme established by the Australian government. It provides opportunities for land owners and local communities to alter land management practices to reduce or sequester carbon emissions. In addition to storing carbon these practices also have the potential to deliver other environmental benefits such as the conservation of biodiversity and the provision of other ecosystem services. The CFI legislation also contains provisions to provide benefits to Indigenous communities, and many indigenous leaders have shown interest in engaging in carbon offset projects.
Various approved methodologies exist within the CFI to guide land managers on how they can sequester carbon in a way that will be acknowledged by the government. Tree planting is one such methodology and, if mixed native trees are planted, this has the potential to provide additional ecosystem services. Mixed plantings also have greater resilience to disturbances. Despite the interest of Indigenous communities in these schemes, determining the optimum locations for tree planting to ensure more’ bang for their buck’ is unknown. We therefore conducted a spatial analysis of the carbon and biodiversity potential of planting biodiverse native vegetation on Indigenous land across Australia (Renwick et al. 2014).
So what does such an analysis entail? Basically it involves comparing all the places on Indigenous land that are suitable for mixed tree plantations for their conservation value, carbon storage value and cost. To do this we compiled three maps which we could overlay on each other. The first was a map of the potentially plantable area across Australia. This is the area that had historically (pre-1750) been covered by vegetation containing trees (that were at least 1.3m tall) but have since been cleared, excluding built up areas.
“Almost 19% of the combined high and very high priority areas for cost-effectively meeting biodiversity goals are on Indigenous lands.”
The second was a comprehensive map of Indigenous tenure across Australia. Indigenous land tenure data was sourced from the official agencies responsible for the registration of various Indigenous land tenures including the National Native Title Tribunal, Conservation and Protected Areas Database, Department of the Environment (formerly Department of Sustainability, Environment, Water, Populations and Communities), Indigenous Land Corporation, National Land and Water Resources Audit and Geoscience Australia. The classes of Indigenous land represent legally recognised tenure, and they vary in the type of rights and opportunities conveyed with the form of tenure.
Vegetation type was used as a surrogate for biodiversity. The 63 major vegetation subgroups from the National Vegetation Information System (NVIS version 3.1) were intersected with the 85 Interim Biogeographic Regionalisation of Australia (IBRA) bioregions to generate 1886 unique vegetation types across Australia. Of these, 1185 vegetation types contained trees of at least 1.3m tall and thus qualified for carbon planting. A total of 139 of these vegetation types have been cleared to below 30% pre-1750 extent and considered a high priority for restoration. We therefore set a target to restore each vegetation type up to 30% of its pre-1750 extent as a biodiversity co-benefit to planting trees for carbon sequestration.
Using the conservation planning tool Marxan and an economic scenario reflecting the Australian government’s 2011-2012 carbon trading price of AU$23/tonne (establishment cost AU$1000 per ha, no water cost, baseline growth rate, discount rate 5%, carbon selling price of $20/tonne), Josie Carwardine and colleagues et al (unpublished data) determined the cost-effectiveness of areas across Australia for sequestering carbon and meeting the vegetation restoration targets of 30% of pre-1750 extent. From this, the relative priority of each 4km2 block within the potentially plantable area for cost effectively meeting the combined carbon and biodiversity goal was determined.
We then overlaid the map of Indigenous land tenure with maps of carbon sequestration, biodiversity features and the relative priority areas to determine the proportion of carbon and biodiversity goals that can be met on Indigenous land.
The price of carbon
Approximately 92 million hectares of land in Australia has been cleared and has the potential to be replanted with native vegetation. This would sequester around 710 Mtonne CO2/year over the next 40 years. The amount of this area that will be available for this activity, however, depends on the profitability for environmental planting. This, in turn, is dependent on the carbon price and other economic considerations. For example, water cost and other social and practical constraints will influence the decisions made by land managers.Figure 2: Map of Indigenous tenure overlaid on carbon sequestered (tonnes) per year per planning unit (4 km2) in plantable areas (Renwick et al., 2014).
Using the 2011-2012 Australian carbon trading price of AU$23/tonne, 31 million hectares of the area is profitable for carbon farming. This would sequester around 294Mt CO2.
Almost a third of this area, 9.7 million hectares, is on Indigenous land which would sequester 83Mt CO2 (28% of the total). If, however, the price of carbon drops to AU$5/tonne, close to the price on international markets in 2013, the profitable area for carbon farming is reduced severely to only 5 million hectares and the potential for Indigenous communities to get involved would be greatly limited (see figures 1 and 2).
Almost half of the plantable area contains 139 vegetation types that have been cleared to below 30% of pre-1750 extent. Almost one fifth of the plantable area on Indigenous land contains 79 vegetation types that have been cleared to below 30% of the pre-1750 extent. Two of the vegetation types can only be restored in a natural ecosystem on Indigenous land.
Almost 19% of the combined high and very high priority areas for cost-effectively meeting biodiversity goals are on Indigenous lands primarily in southeast Queensland, eastern New South Wales, southwest Victoria, southeast South Australia and southwest Western Australia.
There are little carbon and biodiversity benefits from planting on Indigenous land in northern Australia. This reflects the low density of forests and historical clearing that has taken place in northern Australia. Other carbon offset schemes in this area may be more appropriate, for example savanna burning.
Given that Indigenous land cover 19% of the total biodiversity plantable area, this result indicates that Indigenous lands are approximately as important as the rest of Australia for achieving this combined goal cost-effectively (see figure 3).
The analysis discussed here represents a top-down approach to consider the challenge of biodiverse carbon plantations on Indigenous land. It provides one perspective of the potential for Indigenous communities to get involved in carbon projects.
The next stage is to test these model results in partnership with local Indigenous communities. It’s likely that these communities may require additional information, special training and community engagement skills to work through the options.
Despite the positive potential for the CFI to contribute to biodiversity and provide benefits to Indigenous communities and broader society, the recent change in government in Australia highlights the instability of the policy and political environment surrounding the CFI initiative. This opens up new risks and uncertainties to carbon farming efforts, including those adopted by Indigenous communities.
More info: Anna Renwick email@example.com
Renwick AR, CJ Robinson, TG Martin, T May, P Polglase, HP Possingham & Josie Carwardine (2014). Biodiverse Planting for Carbon and Biodiversity on Indigenous Land. PLOS One. DOI: 10.1371/journal.pone.0091281 http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0091281