Variation in foliar nutrients in Eucalyptus trees in eastern and Western Australia

Abstract

Levels of nitrogen, phosphorus and potassium were measured for the foliage of two co-dominant eucalypts at each of two sites, one in eastern Australia and the other in Western Australia. In eastern Australia, foliage was sampled in the canopy and subcanopy for narrow-leaved ironbark Eucalyptus crebra and grey box E. mollucana and in Western Australia, for jarrah E. marginata and marri E. calophylla. The Western Australian trees were also sampled for 'young' and 'old' leaves. Both eucalypts in eastern Australia had greater nitrogen and phosphorus levels, but lower potassium, than E. marginata or E. calophylla. Eucalyptus calophylla foliage had greater levels of all three nutrients than E. marginata foliage as did E. crebra relative to E. mollucana. At both sites, foliar nutrient levels were greater in the canopy than subcanopy foliage, and, at least in Western Australia, the younger leaves had greater nutrient levels than the older leaves. The observed differences in foliar nutrient levels are consistent with observed trends in the abundance and diversity of foliage arthropods and the use of the trees as foraging substrates by birds.