Influence of juvenile growth rates on xylem efficiency and safety in three temperate tree species

In times of climate change, understanding the dependency of plant productivity on xylem hydraulic physiology is of high importance. We studied saplings of three broadleaved tree species grown under favourable and stressed conditions, and related various hydraulic traits to juvenile growth performance.

Except for one species, high productivity was associated with a high hydraulic efficiency caused by large xylem vessels and a large supported leaf area. Although no safety-efficiency trade-off was observed, productivity was significantly related to xylem safety in two of the tree species but without revealing any clear pattern. Furthermore, a considerable plasticity in given traits was observed between stressed and non-stressed individuals, with safety-related traits being more static while efficiency-related traits revealed a higher intra-specific plasticity.

We confirm that a high hydraulic efficiency seems to be a prerequisite for high biomass production, while our controversial results on the growth-xylem safety relationship deserve further attention.