Functional Traits and Water Transport Strategies in Lowland Tropical Rainforest Trees

Deborah M G Apgaua,David Y P Tng,Rubens M Santos,Joseph A M Holtum,Françoise Y Ishida,Rizwana Rumman,Susan G W Laurance,Melinda J Laidlaw,Derek Eamus

doi:10.1371/journal.pone.0130799

Deborah M G Apgaua, David Y P Tng + Show 7 more

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https://doi.org/10.1371/journal.pone.0130799

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Abstract

Understanding how tropical rainforest trees may respond to the precipitation extremes predicted in future climate change scenarios is paramount for their conservation and management. Tree species clearly differ in drought susceptibility, suggesting that variable water transport strategies exist. Using a multi-disciplinary approach, we examined the hydraulic variability in trees in a lowland tropical rainforest in north-eastern Australia. We studied eight tree species representing broad plant functional groups (one palm and seven eudicot mature-phase, and early-successional trees). We characterised the species’ hydraulic system through maximum rates of volumetric sap flow and velocities using the heat ratio method, and measured rates of tree growth and several stem, vessel, and leaf traits. Sap flow measures exhibited limited variability across species, although early-successional species and palms had high mean sap velocities relative to most mature-phase species. Stem, vessel, and leaf traits were poor predictors of sap flow measures. However, these traits exhibited different associations in multivariate analysis, revealing gradients in some traits across species and alternative hydraulic strategies in others. Trait differences across and within tree functional groups reflect variation in water transport and drought resistance strategies. These varying strategies will help in our understanding of changing species distributions under predicted drought scenarios.

Highlights

One of the major threats to earth’s biodiversity are precipitation extremes predicted in future climate change scenarios [1]
Understanding how tropical rainforest trees may respond to the precipitation extremes predicted in future climate change scenarios is paramount for their conservation and management
We explored the coordination of functional traits across 30 rainforest trees using non-metric multidimensional scaling ordination analysis (NMDS)

Summary

Introduction

One of the major threats to earth’s biodiversity are precipitation extremes predicted in future climate change scenarios [1]. Tropical forests are likely to experience more frequent and severe droughts and increased aridity [2, 3], which can result in high levels of hydraulic stress in trees, loss of biomass and increased mortality [4, 5]. Drought is likely to PLOS ONE | DOI:10.1371/journal.pone.0130799. Water Transport Strategies in Tropical Rainforest Trees analysis, decision to publish, or preparation of the manuscript

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