Two decades of fire in Madagascar

Madagascar experiences extensive annual wildfires that profoundly shape its landscape, particularly within its expansive rangelands and agricultural regions. Examining the 2005–2025 MODIS burned-area record reveals high interannual variability driven primarily by seasonal precipitation patterns and broader climatic anomalies such as the El Niño–Southern Oscillation (ENSO). The dynamics of fuel accumulation and subsequent drought periods underscore a complex relationship between rainfall and fire extent.

A tropical savanna fire regime

While historically viewed through the lens of forest degradation, Madagascar's modern fire regimes are largely characteristic of tropical savanna and agricultural systems, similar to most tropical burned areas globally. Fire is frequently used as a land-management tool to clear agricultural plots and renew pastures for livestock grazing. When fires escape into adjacent undisturbed ecosystems, however, they pose severe threats to primary forests and soil health.

The MODIS record

The MODIS sensor aboard Terra and Aqua has provided a continuous, reliable dataset for global fire monitoring since the early 2000s. The standard burned-area product — the 500 m resolution MCD64A1 — combines surface-reflectance change with active-fire thermal anomalies to map burn extent. While effective at capturing landscape-scale fires in open rangelands and savannas, it can underestimate small, fragmented fires at the agricultural-forest interface. Even so, the 2005–2025 MODIS time series remains the most robust framework for macro-level interannual trend analysis in Madagascar.

A dual-phase rainfall relationship

Interannual variability in burned area is inextricably linked to precipitation, through a two-phase "fuel-load and drought" dynamic:

• Accumulation phase — above-average rainfall during the wet season (November–April) promotes rapid herbaceous growth and high biomass production in pastures and agricultural land.
• Curing and burning phase — as the dry season progresses (May–October), that biomass dries into highly combustible fine fuel.

ENSO heavily influences this cycle: during strong El Niño phases, southern and eastern Africa — including Madagascar — often see severe dry conditions, lower humidity, and higher temperatures. When an unusually wet year is immediately followed by El Niño–induced drought, the landscape is primed for wide-spreading fires. In this dataset, April and May 2016 — the tail of one of the strongest El Niño events on record — burned 2–4× above their 21-year monthly average, consistent with that dynamic. Conversely, continuous multi-year droughts can eventually suppress total burned area by limiting fuel continuity.

Landscape degradation feedback loop

Escaped fires from agricultural land and grazing pastures frequently breach the boundaries of tropical dry forests. Even without stand-replacing canopy loss, they damage the understory and forest edges, facilitating grass encroachment. This creates a positive feedback loop: as grasses invade the forest edge, the area becomes more fire-prone, gradually converting complex forest ecosystems into simplified, fire-prone shrublands or savannas.

Conclusion

The 2005–2025 MODIS record shows Madagascar's wildfires as a persistent, highly dynamic landscape feature — not merely a function of human land use, but heavily dictated by preceding and current precipitation conditions. As climate variability increases, integrating high-resolution precipitation datasets with satellite burned-area monitoring will be vital for predicting extreme fire years and safeguarding both rangelands and vulnerable forest borders.

References

• Axel, A. (2018). Burned Area Mapping of an Escaped Fire into Tropical Dry Forest in Western Madagascar Using Multi-Season Landsat OLI Data. Remote Sensing, 10(3), 371. doi.org/10.3390/rs10030371
• Chuvieco, E., Lizundia-Loiola, J., Pettinari, M. L., Ramo, R., Padilla, M., Tansey, K., Mouillot, F., Laurent, P., Storm, T., Heil, A., & Plummer, S. (2018). Generation and analysis of a new global burned area product based on MODIS 250 m reflectance bands and thermal anomalies. Earth System Science Data, 10(4), 2015–2031. doi.org/10.5194/essd-10-2015-2018
• Phelps, L. N., Andela, N., Gravey, M., Davis, D. S., Kull, C. A., Douglass, K., & Lehmann, C. E. R. (2022). Madagascar's fire regimes challenge global assumptions about landscape degradation. Global Change Biology, 28(23), 6944–6960. doi.org/10.1111/gcb.16206
• Shikwambana, L., Kganyago, M., & Xulu, S. (2022). Analysis of wildfires and associated emissions during the recent strong ENSO phases in Southern Africa using multi-source remotely-derived products. Geocarto International, 37(26), 16654–16670. doi.org/10.1080/10106049.2022.2113449