Near-surface chemical properties of soils in the Australian Alps

Abstract

Alpine soils are globally threatened and are highly vulnerable to the impacts of disturbance. In Australia, alpine soils are critically understudied and remain poorly understood. Here, the soil chemical properties of four common soil types across the Australian Alps were investigated. Soil carbon (C) and nitrogen (N) concentrations, carbon and nitrogen densities (mg cm3), carbon-to-nitrogen ratios (C:N), electrical conductivity (EC), and pH were quantified among four soils: peat soils (organosols), alpine humus soils, skeletal mountaintop soils, and disturbed soils (anthroposols). All measured soil chemical properties varied significantly among different soils, highlighting the value of understanding site-specific edaphic factors to enhance the success of restoration interventions in the Australian Alps. Large C concentrations (17.5 ± 16.6%) and C:N (30.2 ± 25.5), together with low pH (4.2 ± 0.8), EC (66.8 ± 59.6 ɥs cm−1), and N concentrations (0.55 ± 0.3%), indicate nutrient-poor soils with relatively recalcitrant C stocks across the Australian Alps, particularly in peat soils. Carbon and nitrogen densities, conversely, were greater in the alpine humus and disturbed soils, due to greater bulk densities in these soils. These results suggest that the 12,300 km2 Australian alpine bioregion appears to represent a significant terrestrial C reservoir, which may be negatively impacted by climate change. Furthermore, the findings presented suggest that active restoration of the soil physico-chemical environment alongside revegetation activities could enhance the protection of alpine soil carbon into the future.