Recovery of soil and vegetation in semi-arid Australian old fields

Abstract

Due to the harsh environmental conditions of arid and semi-arid regions, recovery of native plant communities after abandonment from cultivation is hypothesised to be slow and unlikely to return to pre-disturbance condition. We examined vegetation and soil parameters along a ∼100 year chronosequence of agricultural field abandonment in semi-arid grasslands in south-eastern Australia to quantify resilience. Native species richness, abundance and composition converged towards those of uncultivated grasslands, and there was a replacement of initial exotic dominance by native perennial grasses. Thus, the vegetation did not enter an alternative stable state and the community variables studied showed some resilience. However, many native species failed to recolonise, and native species richness, composition and abundance remained significantly different from uncultivated grasslands over the span of the study. Soils demonstrated post-abandonment recovery, with differences to uncultivated grassland in most nutrients becoming non-significant by ∼50 years, and soils did not appear to be the main driver of vegetation patterns with time-since-abandonment. The basic patterns of community reassembly did not appear to be fundamentally different from temperate northern hemisphere old field succession and suggest that secondary succession in Australian semi-arid grasslands may be constrained by seed availability rather than environmental conditions.