Developing the northern savannas

Trade-offs between biodiversity, carbon and agricultural development

By Alejandra Morán-Ordóñez (Centre Tecnològic Forestal de Catalunya, Solsona, Spain and the University of Melbourne)


KEY MESSAGES:

  • We explored trade-offs among biodiversity conservation, carbon farming & agriculture production in northern Australia.
  • If agricultural development proceeded without consideration of biodiversity, suitable habitat of 3 species would disappear and 40 species and vegetation
    communities could lose more than 50% of their current distributions.
  • Strategically considering potential biodiversity outputs when planning for agricultural development leads to zoning options that would have a significantly lower impact on biodiversity values and carbon farming.

There’s a lot of talk about developing Australia’s north, of doubling the agricultural output of this region and pouring billions of dollars into new infrastructure such as irrigation. But what about the natural values of this region and it’s potential for carbon storage today and into the future? Can we develop the north and still retain these other values?

The northern savanna in its natural condition. (Photo by James Fitzsimons)

The northern savanna in its natural condition. (Photo by James Fitzsimons)

Our spatial analysis revealed that the impact of agricultural development in northern Australia depends on how and where it’s done. It could have a profound impact on biodiversity OR a relatively light impact. Given this, if managers and decision makers want our sweeping northern savannas to serve multiple purposes then they need to plan strategically for them.

The northern savannas occupy a vast area, approximately the combined size of both France and Germany! This region possesses a relatively intact cover of native vegetation largely consisting of open eucalypt woodlands with a grass understorey. The savannas currently support lowintensity rangeland grazing. Being largely intact, they provide home for a broad suite of native animals and plants, many of which are endemic. In recent years it’s been realised that these lands also hold considerable potential for the storage of carbon by managing the manner in which fires occur (and therefore contribute to climate change mitigation).

But there are many calls to develop Australia’s north. Based on soil properties, a fifth of this region is also deemed highly suitable for agricultural intensification. What are the consequences of enabling intensive agriculture in these places?

We analysed the trade-offs between biodiversity, carbon, and agricultural intensification in northern Australia. We compared maps of agricultural intensification potential, with the geographic distributions for 611 native species and 43 vegetation communities to see how they overlap.

We also compared the distribution of areas with larger carbon storage potential that are suitable for carbon farming.

Using this information, we explored five alternative scenarios that looked at different approaches to development and how these could impact the unique biodiversity values of this region. One scenario evaluated what might happen if only agriculture was considered in planning for agricultural expansion (agriculture-only); another if biodiversity conservation was the only consideration (biodiversity-only); the third was if only carbon-farming was considered (carbon-only); the fourth was if farming, biodiversity and carbon were all given equal weighting, seeking to balance the three goals (all-equal); and the final scenario looked at saving as much biodiversity as possible while still allowing for carbon farming and significant agricultural development (biodiversity-weighted).

We found that if all suitable soils were converted to agriculture, that all of the suitable habitat of three species would disappear, and 40 species and vegetation communities could lose more than 50% of their current distributions.

Irrigated agriculture in the Ord River Development. Developing the north will involve trade-offs with biodiversity. (Photo by Garry Cook)

Irrigated agriculture in the Ord River Development. Developing the north will involve trade-offs with biodiversity. (Photo by Garry Cook)

But agricultural development doesn’t have to have this impact. Our analysis showed that it’s possible to zone this region such that agricultural development could still occur on over 56,000 km2 with a significantly lower impact on biodiversity values and carbon farming.

There is a significant opportunity to dramatically increase the protection of biodiversity with a minor expansion of the reserve system in northern Australia. By expanding the protected area network to capture an additional 5% of northern Australia, we could effectively double the representation of the biodiversity features from 29% to 57% (ie, the average proportion of current suitable areas for species that could be protected).

The development of extensive areas of irrigated agriculture might also cause potentially negative impacts on other industries such as tourism. Our approach could be built on to help evaluate trade-offs during planning and decision-making in relation to agricultural development in northern Australia, that incorporates more attributes than we have included in our study. For example, many other cultural, historical, social and economic can be mapped to provide an early indication of likely conflicts and trade-offs. The advantage of our approach is that
it helps identify development footprints that have the lowest possible impact on biodiversity, while still providing strong economic opportunity. It can also help to identify where in the landscape are places that should most urgently be protected to avoid the worst outcomes of development for biodiversity.

Figure 1a: Degree of overlap between any area suitable for agriculture and high priority areas (best 5%, 10%, and 30%) for biodiversity conservation only and carbon storage only (area in squared km). For example, whereas 30,406 km2 of northern Australia has been identified as high priority for biodiversity (within the top 5 % of the biodiversityonly scenario landscape ranking), only 4,520 km2 overlaps with high priority areas for carbon storage (within the top 5% of the carbon-only scenario).

Figure 1a: Degree of overlap between any area suitable for agriculture and high priority areas (best 5%, 10%, and 30%) for biodiversity conservation only and carbon storage only (area in squared km). For example, whereas 30,406 km2 of northern Australia has been identified as high priority for biodiversity (within the top 5 % of the biodiversityonly scenario landscape ranking), only 4,520 km2 overlaps with high priority areas for carbon storage (within the top 5% of the carbon-only scenario).


Figure 1b: Venn diagram showing the areas of potential conflict (trade-offs) or synergies between the three land-uses as well as their implications for policy making.

Figure 1b: Venn diagram showing the areas of potential conflict (trade-offs) or synergies between the three land-uses as well as their implications for policy making.

The work has application beyond northern Australia. The analysis provides a template for policy-makers and planners to identify areas of conflict between competing land-uses, places to protect in advance of impacts, and planning options that balance the needs of agricultural and conservation.

Figure 2: Performance of biodiversity features under five prioritization scenarios. The X-axis shows the proportion of the biodiversity features’ distributions remaining at different levels of landscape lost due to conversion to agriculture. Lines represent the average performance of biodiversity features within the bottom 10th percentile of data for each scenario: biodiversity-only, carbon-only, agriculture-only, all-equal and biodiversity weighted. Comparison between scenarios can be made at any threshold of landscape conversion along the X-axis. For example, a conversion of all suitable soils for agriculture into irrigated crops or pasturelands would imply approximately 20% of landscape loss for other land-uses (dotted black vertical line marked with the letter b). At this proportion of landscape loss, the agriculture-only scenario predicts that the average distributions remaining for the worst 10% of the biodiversity features is 0.38 versus the 0.75 predicted by the biodiversity only scenario (ie, a reduction of approximately 50% in predicted distributions between the two scenarios).

Figure 2: Performance of biodiversity features under five prioritization scenarios. The X-axis shows the proportion of the biodiversity features’ distributions remaining at different levels of landscape lost due to conversion to agriculture. Lines represent the average performance of biodiversity features within the bottom 10th percentile of data for each scenario: biodiversity-only, carbon-only, agriculture-only, all-equal and biodiversity weighted. Comparison between scenarios can be made at any threshold of landscape conversion along the X-axis. For example, a conversion of all suitable soils for agriculture into irrigated crops or pasturelands would imply approximately 20% of landscape loss for other land-uses (dotted black vertical line marked with the letter b). At this proportion of landscape loss, the agriculture-only scenario predicts that the average distributions remaining for the worst 10% of the biodiversity features is 0.38 versus the 0.75 predicted by the biodiversity only scenario (ie, a reduction of approximately 50% in predicted distributions between the two scenarios).

 


More info: Alejandra Moran alejandra.moran@ctfc.es
Reference: Morán-Ordóñez A, AL Whitehead, GW Luck, GD Cook, R Maggini, JA Fitzsimons & BA Wintle (2016). Analysis of trade-offs between biodiversity, carbon farming and agricultural development in northern Australia reveals the benefits of strategic planning. Conservation Letters online, open access.

Leave a Reply