Rare plant species occurrence patterns are associated not with soil properties, but with frequent fire in a southeast Australian dry sclerophyll forest

Abstract

QuestionSoil properties can play a crucial role in influencing the abundance and distribution of plant species. Fire regimes can also have substantial impacts on plant community composition. However, few studies have examined the effects of both fire regimes and soil properties on the occurrence of rare plant species. Here, we asked if rare species have specific soil and fire regime associations relative to common species, and if soil properties may explain potential fire effects.LocationBooderee National Park, southeastern Australia.MethodsWe collected soil cores and completed vegetation surveys on 42 sites in Sydney Coastal Dry Sclerophyll Forest vegetation. We tested for associations between the number of rare species and common species present in relation to three soil chemical properties (available phosphorus, ammonium and organic carbon), fire frequency, and time since fire.ResultsWe found that rare and common species were not associated with any of the examined soil properties. However, rare species were associated with sites with a high fire frequency, while common species were negatively associated with time since fire.ConclusionsOur results indicate that rare species’ occurrence patterns may be influenced by the direct effects of fire or mediated by multiple factors, rather than shaped solely by soil properties in our study area. Future work to understand the factors that underpin rare species’ occurrence patterns in response to fire is critical to develop fire management protocols that effectively conserve rare species in dry sclerophyll forests.