FOLIAR NUTRIENTS IN RELATION TO GROWTH, ALLOCATION AND LEAF TRAITS INSEEDLINGS OF A WIDE-RANGE OF WOODY PLANT-SPECIES AND TYPES

This study aimed to identify functional correlates of seedling leaf nu trient content among woody species and to characterise functional spec ies groups with respect to leaf nutrient attributes. Seedlings of 81 w oody species from the temperate zone of western Europe were grown in a standard laboratory environment with standard, near-optimal nutrient availability. Weight-based leaf N content (N-wght) was positively corr elated with mean relative growth rate (RGR), but the correlation with mean RGR was tighter when leaf N was expressed on a whole-plant weight basis: leaf nitrogen weight ratio (LNWR). Area-based leaf N content ( N-area) was not associated with mean RGR, but was closely correlated w ith the quotient of saturated leaf weight and leaf area. Weight-based leaf K content (K-wght) was a close correlate of the saturated/dry wei ght ratio of the foliage, Within the lower range, K-wght corresponded with growth-related nutrient attributes, but higher values appeared to indicate succulence or remobilisable stored water. Functional groups of species and genera could be distinguished with respect to seedling leaf nutrient attributes. Deciduous woody climbers and scramblers had consistently higher leaf N-wght, LNWR and (apparently) leaf K-wght tha n other deciduous species or genera, and shrubs had higher values than trees. These differences seemed due partly to variation in specific l eaf area. Evergreens had consistently higher leaf N-area than deciduou s plants, but there were no significant differences in weight-based le af nutrient attributes between these two groups, possibly because of ' luxury nutrient consumption' by the slow-growing evergreens. Another f unctional group was that of the nitrogen-fixing species, which had con sistently high innate leaf N-wght compared to non-N-fixers. The ecolog ical significance of the leaf nutrient attributes in this study is dis cussed by comparing the seedling data with those from field-collected material, and by brief reference to the natural habitats of the specie s.