Mineral nutrition of sub-alpine Australian vegetation under nutrient deficiency depends on lifeform

Abstract

We sought to elucidate if the perennial lifestyle per se, or lifeform, enhances independence of soil nutrient availability. We measured parameters of CO 2 fixation and electron transport, stomatal conductance, P and N nutrition, as well as integrative water relations (δ 13 C abundance) of an overstory tree (Snow Gum; Eucalyptus pauciflora, Sieber ex Spreng.) and a perennial understory shrub (Alpine Shaggy-pea; Podolobium alpestre F. Muell.) at two Australian field sites with different soil nutrient availability, but otherwise similar environmental conditions. Snow Gums are renowned for their longevity, including the ability to re-sprout profusely after fire, while Alpine Shaggy-pea has a relatively short lifespan, and regenerates from seed after fire. Photosynthesis parameters of P. alpestre were more sensitive to soil properties than for E. pauciflora. P and N status of leaves and roots of E. pauciflora were comparable at both sites, whereas P and N status of P. alpestre reflected their availability in the soil. Differences in δ 13 C abundance of the two species studied indicated the use of different water sources at both field sites. These results suggest that long-lived plants with the capability to recycle nutrients from woody tissues, can grow largely independent of soil P and N availability.