The fire refuge value of patches of a fire-sensitive tree in fire-prone savannas: Callitris intratropica in northern Australia

Patches of fire-sensitive vegetation often occur within fire-prone tropical savannas, and are indicative of localized areas where fire regimes are less severe. These may act as important fire refugia for fire-sensitive biota. The fire-sensitive tree <i>Callitris intratropica</i> occurs in small patches throughout the fire-prone northern Australian savannas, and is widely seen as an indicator of low-severity fire regimes and of good ecosystem health. Here, we address the question: to what extent do <i>Callitris</i> patches act as refuges for other fire-sensitive biota, and therefore play a broader conservation role? We contrast floral and faunal species composition between <i>Callitris</i> patches and surrounding eucalypt savanna, using three case studies. In the first case study, a floristic analysis of 47 <i>Callitris</i> patches across Western Australia's Kimberley region showed that woody species in these patches were overwhelmingly widespread, fire-tolerant savanna taxa. No species of special conservation concern occurred disproportionately within <i>Callitris</i> patches. Similarly, there was no concentration of fire-sensitive fauna or flora in five <i>Callitris</i> patches in the East Kimberley. Finally, there was no difference in ant species composition among 12 <i>Callitris</i> patches and surrounding eucalypt savannas in Kakadu National Park, Northern Territory, and there were no fire-sensitive ant species in <i>Callitris</i> patches. Our three case studies from throughout the northwestern Australia provide no evidence that <i>Callitris</i> patches act as important refuges for fire-sensitive flora or fauna within fire-prone eucalypt savannas. This calls into question the notion that <i>Callitris</i> is a strong indicator of general ecosystem health.