The hydraulic efficiency-safety trade-off differs between lianas and trees.

Lourens Poorter,Bettina M. J. Engelbrecht,Masha T. Sande,Stefan A. Schnitzer,Lars Markesteijn

doi:10.1002/ecy.2666

Abstract

Hydraulic traits are important for woody plant functioning and distribution. Associations among hydraulic traits, other leaf and stem traits, and species’ performance are relatively well understood for trees, but remain poorly studied for lianas. We evaluated the coordination among hydraulic efficiency (i.e., maximum hydraulic conductivity), hydraulic safety (i.e., cavitation resistance), a suite of eight morphological and physiological traits, and species’ abundances for saplings of 24 liana species and 27 tree species in wet tropical forests in Panama. Trees showed a strong trade‐off between hydraulic efficiency and hydraulic safety, whereas efficiency and safety were decoupled in lianas. Hydraulic efficiency was strongly and similarly correlated with acquisitive traits for lianas and trees (e.g., positively with gas exchange rates and negatively with wood density). Hydraulic safety, however, showed no correlations with other traits in lianas, but with several in trees (e.g., positively with leaf dry matter content and wood density and negatively with gas exchange rates), indicating that in lianas hydraulic efficiency is an anchor trait because it is correlated with many other traits, while in trees both efficiency and safety are anchor traits. Traits related to shade tolerance (e.g., low specific leaf area and high wood density) were associated with high local tree sapling abundance, but not with liana abundance. Our results suggest that different, yet unknown mechanisms determine hydraulic safety and local‐scale abundance for lianas compared to trees. For trees, the trade‐off between efficiency and safety will provide less possibilities for ecological strategies. For lianas, however, the uncoupling of efficiency and safety could allow them to have high hydraulic efficiency, and hence high growth rates, without compromising resistance to cavitation under drought, thus allowing them to thrive and outperform trees under drier conditions.

Highlights

Hydraulic efficiency, safety, and associated traits are important in determining tree species’ functioning (Sterck et al 2011, Cosme et al 2017) and response to drought (Rowland et al 2015, Anderegg et al 2016) and Manuscript received June 2018; revised November 2018; accepted 14 January 2019
We evaluated the coordination among hydraulic efficiency, hydraulic safety, a suite of eight morphological and physiological traits, and species’ abundances for saplings of 24 liana species and 27 tree species in wet tropical forests in Panama
Lianas had higher hydraulic efficiency and lower hydraulic safety than trees (Appendix S5), similar to what we found in an earlier study for only part of these data

Summary

Introduction

Safety, and associated traits are important in determining tree species’ functioning (Sterck et al 2011, Cosme et al 2017) and response to drought (Rowland et al 2015, Anderegg et al 2016) and Manuscript received June 2018; revised November 2018; accepted 14 January 2019. Lianas generally have lower hydraulic safety and wood density due to less investment in supporting stem tissues, and higher hydraulic efficiency (Zhu and Cao 2009, van der Sande et al 2013, De Guzman et al 2016). De Guzman et al (2016) found a trade-off between hydraulic efficiency and safety among six liana and six tree species in a seasonally dry tropical forest in Panama, which appeared similar for lianas and trees (Santiago et al 2015). They did not formally test for differences between lianas and trees in the efficiency–safety trade-off

Methods

Results

Discussion

Conclusion