Scale-dependent trait correlations in a temperate tree community

Recent investigations of relationships among plant traits have generated important insights into plant form and function. However, relationships involving leaf area, leaf shape and plant height remain poorly resolved. Previous work has also focused on correlations between average trait values for individual species. It is unclear whether similar relationships occur within species. We searched for novel plant trait correlations by comparing leaf area, leaf circularity, specific leaf area (SLA) and plant height among 16 common woody plant species from a temperate forest in New Zealand. Analyses were conducted both within species (intra-specifically) and among species (inter-specifically) to determine whether trait correlations were scale dependent. Leaf area was unrelated to other leaf traits inter-specifically. However, leaf area declined with plant height and increased with SLA intra-specifically. Leaf circularity decreased with plant height inter-specifically, but increased with plant height intra-specifically. SLA increased with plant height both inter- and intra-specifically. Leaf circularity increased with SLA inter-specifically, but decreased with SLA intra-specifically. Overall results showed that leaf shape, SLA and plant height are interrelated. However, intra-specific relationships often differed substantially from inter-specific relationships, suggesting that the processes shaping relationships between this suite of plant traits are scale-dependent.