The importance of fire season when managing threatened plant species: A long-term case-study of a rare Leucopogon species (Ericaceae)

• Published in: Journal of environmental management Vol. 236; pp. 17 - 24
• Main Author: Ooi, Mark K.J.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 15-04-2019
• Subjects: Fire ecology; Fire interval squeeze; Mediterranean versus non-Mediterranean climates; Physiological dormancy; Plant functional traits; Seed ecology; Fire interval squeeze; Fire ecology; Plant functional traits; Physiological dormancy; Mediterranean versus non-Mediterranean climates; Seed ecology
• ISSN: 0301-4797; 1095-8630
• DOI: 10.1016/j.jenvman.2019.01.083

Implemented burns are a primary source of fire in natural systems and occur outside of the wildfire season. However, the impacts of fire season shift on native plant species are rarely studied. Understanding fire season effects are particularly important for managing threatened species, which are often the focus of managed burns. To assess the impacts of fire seasonality and identify potential limiting traits, I studied the threatened Leucopogon exolasius and two common congeners, all of which persist via fire-driven population dynamics. All species were monitored over a 16 year period to assess seedling survival, growth and primary juvenile period after fire. For L. exolasius and the common L. esquamatus, comparisons of survival, growth and maturation were made after winter and summer fires, to assess the effects of season of burn. A key difference was found in primary juvenile period, which was exceptionally long for L. exolasius (>11 years for 80% of the population to flower) compared to the common congeners (3.2–7.57 years). Seasonal seed dormancy mechanisms meant that winter fires delayed emergence, leading to increases in primary juvenile period for both species. A long primary juvenile period may limit L. exolasius population persistence because plants are more likely to be killed by subsequent fire before maturation, while seasonal dormancy cues is a trait that would exacerbate the effects of this interval squeeze. In fire-prone systems, fire frequency is the key factor assumed to drive persistence, however, interactions with fire season can influence recruitment success. There are scant data on recruitment variation in response to fire seasonality, a factor that may have broad implications for rare and common species with seasonal germination requirements.
•Implemented fires and climate change are causing shifts in the fire regime.•Seasonal timing of fire can affect the post-fire recovery of plant species.•Out-of-season fires can result in slow growth and delayed reproduction.•Seasonally emerging species with long juvenile periods may be particularly affected.•Managers need to consider multiple aspects of fire regime for effective management.