Occurrence of Australian woody species is driven by soil moisture and available phosphorus across a climatic gradient

Abstract

AbstractQuestionsWoody species are crucial biotic components in many of Earth’s terrestrial ecosystems because they support multiple ecosystem functions. The occurrence of woody species (i.e. their likelihood of being present at a single position) is driven by both climate and soil properties. However, empirical evidence is lacking on how multiple environmental factors regulate woody species occurrence across various climate regimes, limiting our ability to predict woody species distribution under different climate change scenarios.LocationWoody plant species in eastern Australia; 1,500 km gradient.MethodsWe surveyed 6,353 mature (height >4 m) woody plants from 62 woody species at 150 sites along a 1,500 km climatic (i.e. aridity) gradient in eastern Australia, and used a generalized linear mixed model to explore the impact of summer rainfall, available soil phosphorus in the surface layer (0–10 cm), subsurface (100–200 cm) soil moisture and clay content, and interactions between aridity and the three soil variables on woody species occurrence (presence/absence).ResultsThe overall occurrence of Australian woody species declined as the concentration of available soil phosphorus in the surface layer increased, with the impacts varying with increasing aridity. Subsurface soil moisture had strong positive effects on woody species occurrence in mesic areas, but the effect was attenuated with increasing aridity. Subsurface soil clay regulated the distribution of woody species, with finer soils promoting the likelihood of species occurrence in the dry subhumid zone, whereas coarser soils supported more woody species in the arid zone.ConclusionsOur study provides empirical evidence that the distribution of Australian woody species is regulated by large‐scale shifts in soil moisture and available soil phosphorus, and local‐scale heterogeneity in soil texture. Our results suggest that forecasted climate change may restrict the distribution of woody species preferring particular soils, but expand the range of woody species that occur on dry or infertile soils.