Madagascar’s fire regimes compared to the rest of the tropics

Figure 3 from Phelps et al. (2022). Colours represent areas with similar fire regimes (clustered based on burnt area, fire size, seasonality, and numbers of fires). Black pixels represent fire regimes not found on Madagascar. Gray pixels are places without landscape-scale fire regimes. Photos: (a) tapia branch and chameleon at Ibity, (b) uncontrolled, peri-urban landscape fire in Ambositra [photo C. Kull, 2019], (c) a forest-savanna boundary in Ambohitantely, (d) ancient biodiverse grasslands on Ibity, (e) landscape fire in an agricultural region near Ambositra, likely for grassland renewal [photo by C. Kull, 1998/9], (f) tree cover on a forest-savanna boundary in Ambohitantely, (g) smallholder land use on Ibity.

Bushfire is often seen as symbolic of environmental catastrophe on Madagascar. But is it? A global comparison of fire regimes based on satellite image data suggests care in jumping to such conclusions. A recent article in Global Change Biology, led by Leanne Phelps and to which I contributed, finds that the island’s fire regimes have analogues to 88% of fire regimes in the global tropics with similar climate and vegetation. Madagascar’s fires, while exceptionally vilified, are not exceptional. It also demonstrates that the large, landscape-scale grassland fires common across highland and western Madagascar have no relationship to forest loss; indeed forest loss occurs in places without large-scale fires.

So when Malagasy musician Rajery sings in his 1999 song Dorotanety that fire is not good, fire destroys the forest, kills animals, and dries out the land (Tsy tsara ny doro tanety / Tsy tsara mandoro tanety / Doro tanety manimba ny ala / Doro tanety mamono bibi / Doro tanety mahamaina ny tany / Eeeeh, aza doroin’eee), he is certainly painting things too starkly. He is repeating an anti-fire discourse whereby for elites and outsiders, as noted in the opening lines of a sharp opinion piece in the Tribune de Madagascar, Madagascar’s environmental challenge is simplified to preserving lemurs threatened by fire.

The paper’s findings questions two widespread assumptions. First, the presumption that human-caused fires in open landscapes (like grasslands) push back forest-grassland boundaries, nibbling away at forest edges. The data show that grassfires in Madagascar were decreasing at the same time as high forest degradation rates, and that fires along forest-savanna boundaries are unlikely to be driving the island’s rapid deforestation. Second, the presumption that human-caused fires are central to deforestation, and can be seen as a proxy for human degradation pressure. Our data shows that forest loss occurs mostly in areas without large-scale landscape fires, and more related to active tree clearing (with our without small-scale fire) linked to crop production.

There is much more research to do. The paper only looked at fires burning over 21 hectares (a fifth of a square kilometre), ignoring the large number of small-scale fires used by farmers. It is important not to conflate such small-scale fires, some used for forest clearance, others for farm and field management, with large landscape scale fires such as those common in pastoral burning in extensive rangelands.

I’m thrilled that there seems to be renewed interest in fire research on Madagascar. Our paper confirms with satellite data some of the ideas I tested out in my 2004 book “Isle of Fire: the political ecology of landscape burning in Madagascar” (University of Chicago Press), and brings surprising new findings (such as a two decade decline in overall fire in Malagasy grassy biomes). In that book, I traced the reasons rural Malagasy farmers and herders light fires, why officials have sought to vilify fires, and how this has led to a century-long fire conflict. Better understanding of fire’s ecology, utility, and risks, and better dialogue between urban policy makers and rural residents, are crucial for the island. (By the way, my book is still available from the University of Chicago Press website and other booksellers; there is also a PDF author’s version here).

Reference

Phelps, LN, N Andela, M Gravey, DS Davis, CA Kull, K Douglass & CER Lehmann (2022) Madagascar’s fire regimes challenge global assumptions about landscape degradation. Global Change Biology. dx.doi.org/10.1111/gcb.16206.

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