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How do frequent fires affect fire-sensitive trees in Australian savannas?

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Flat savanna plain with scattered acacia trees under a partly cloudy sky in Serengeti National Park, Tanzania. — Savanna A savanna marked with acacia trees in Serengeti National Park, Tanzania. Africa's Serengeti Plain is commonly used as an example of the savanna biome—a hot, seasonally dry ecological region characterized by an open tree canopy (i.e., scattered trees) above an understory of continuous grasses.

In Australian savannas, frequent fires act as a significant ecological filter that limits the distribution of fire-sensitive tree species. While fire-adapted plants—most notably eucalyptus trees—thrive in these conditions due to specialized traits like thick, protective bark and the ability to resprout from shielded buds, fire-sensitive species are often excluded from the broader landscape.1

For example, the cypress pine (Callitris) is highly drought-tolerant but lacks the fire resistance of dominant savanna flora. Because of this sensitivity, frequent burning restricts Callitris to fire-protected refuges, such as rocky outcrops and gorges, where they are shielded from the intensity of dry-season fires.1

In contrast, areas that remain unburned for extended periods may see a shift in vegetation structure, as fire-sensitive species are able to expand beyond these protected sites. Consequently, the prevalence of fire-sensitive trees in the Australian savanna is largely determined by the frequency and timing of wildfire, which maintains the dominance of pyrophytic (fire-adapted) vegetation across the region.1