Fire regimes challenge global theories on landscape degradation
Unprecedented levels of landscape degradation, centring on fire, have been making adverse headlines for the mega diverse habitats of Madagascar. Yet, while burn scars from past blazes are certainly a feature of the landscape, research published today* by a team of international scientists raises doubts about the authenticity of old claims over unsustainable fire use for pastoral farming in grasslands. The answer is less obvious than previously thought and unexplained anomalies in the relationship between fire and tree loss requires a rethink of what drives degradation on Madagascar.
The team found that landscape fires (>0.21km2) did not explain high tree loss on the island and closer investigation of small-scale fire processes was needed. They say their study demonstrates that to support international sustainable and co-beneficial land management targets, such as the 2021 United Nation’s Climate Change Conference COP26 pledge to halt forest loss and landscape degradation by 2030, a local-to-global understanding of fire is needed to determine how fire relates to people and ecosystems in different socio-ecological contexts.
Better practical understanding of fire regimes is critical, as global change and land management decisions aiming to diminish fire in open ecosystems are, in fact, capable of increasing fire risk and degradation, particularly in forests. The main drivers of globally high degradation rates need to be identified to stem landscape degradation and forest loss and support local livelihoods. Adaptive approaches to fire risks are increasingly important as the island and its people grapple with diminishing biodiversity, food insecurity and intensifying climate change.
Lead author Dr Leanne N Phelps, a postdoctoral researcher with the Royal Botanic Garden Edinburgh (RBGE) and the University of Edinburgh explained: “People manage landscapes and shape biodiversity around the world through various forms of fire use. As a global biodiversity hotspot with high rates of forest loss, the relationships between fire, vegetation and people on Madagascar remain poorly understood. By comparing the island to the global tropics, we found that contrary to popular belief the island’s fire regimes were similar to 88 percent of the tropical burned areas, and high tree loss anomalies were centred in environments without landscape-scale fire. Rather than explaining Madagascar’s high degradation rates, landscape-scale fire declined across tropical grassy biomes and could not be seen as a uniform indicator of forest loss."
Highlighting the importance of the study, Dr Caroline Lehmann, Head of Tropical Diversity at RBGE and Associate Professor at the School of GeoSciences, University of Edinburgh added: “Fire is a complex environmental process that is often reduced to ‘people light fires and fires are bad’. In reality, landscape fire has been a process shaping biodiversity and ecosystems on Earth for as long as there have been plants on land to burn. Indeed, many of Earth’s ecosystems are adapted to and depend on fire but these patterns are changing quickly because of increasing human pressures and climate change. The comparative picture developed here between Madagascar and the global tropics shows how fundamental it is to recognise patterns of fire in grasslands and savannas as different to that in forests. Understanding this ecological nuance helps us move the dial in discussions about land management in an era of radical environmental change. Recognising and distinguishing these fire regimes is central to developing appropriate and effective fire and land management policies supporting people and biodiversity. There is no one size fits all when it comes to managing fire and fire risk.”
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* Madagascar's fire regimes challenge global assumptions about landscape degradation is published online today by Global Change Biology
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