Rarity and nutrient acquisition relationships before and after prescribed burning in an Australian box-ironbark forest

Exocarpos cupressiformis – a relatively rare species in the box-ironbark ecosystem we studied–made a unique contribution to nutrient cycling. The leaf litter (photosynthetic stems) it shed contained concentrations of phosphorus and potassium that were 3.75 and 7.75 times greater, respectively, than average concentrations for leaf litter in the community. Both nutrients are scarce in the ecosystem. Where it occurs, this species likely plays an important role in community productivity. Image credit: John Patykowski.

Nutrient cycling is greatly influenced by dominant plants that contribute high amounts of leaf litter to soils; however, less-dominant and rare species can play key roles in nutrient cycling if they have unique nutrient acquisition traits and provide high-quality litter. In many parts of the world, wildfire is likely to become more frequent and intense under a changing climate, and the effect this will have on plant rarity and on species with unique nutrient acquisition traits, and thus nutrient cycling, remains poorly understood.

In a recent study published in AoB PLANTS, Patykowski et al.examined the relationship between nutrient acquisition strategies, senesced leaf nutrient profiles, and species rarity before and after prescribed burning in a nutrient-poor box-ironbark forest in southeastern Australia. Whilst no community-wide relationship between rarity and uniqueness of leaf nutrient profiles was found, some of the rarest species were functionally unique. Two hemiparasitic species were relatively rare in the ecosystem studied and differed greatly from other species due to high concentrations of phosphorous and potassium in senesced leaves. This study highlights the importance of identifying and conserving species with unique traits (such as hemiparasitism) to prevent loss of functional contributions to ecosystem function.

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