Convergent production and tolerance among 107 woody species and divergent production between shrubs and trees.

Wei-Ming He,Zhen-Kai Sun

doi:10.1038/srep20485

Abstract

Green leaves face two fundamental challenges (i.e., carbon fixation and stress tolerance) during their lifespan. However, the relationships between leaf production potential and leaf tolerance potential have not been explicitly tested with a broad range of plant species in the same environment. To do so, we conducted a field investigation based on 107 woody plants grown in a common garden and complementary laboratory measurements. The values, as measured by a chlorophyll meter, were significantly related to the direct measurements of chlorophyll content on a leaf area basis. Area-based chlorophyll content was positively correlated with root surface area, whole-plant biomass, leaf mass per area (LMA), and force to punch. Additionally, LMA had a positive correlation with force to punch. Shrubs had a higher leaf chlorophyll content than trees; however, shrubs and trees exhibited a similar leaf lifespan, force to punch, and LMA. These findings suggest that the production potential of leaves and their tolerance to stresses may be convergent in woody species and that the leaf production potential may differ between shrubs and trees. This study highlights the possibility that functional convergence and divergence might be linked to long-term selection pressures and genetic constraints.

Highlights

Leaf stress tolerance potential either across 107 woody species or between functional types
We answered two secondary questions: (1) whether the value measured by a portable SPAD-502 chlorophyll meter (SPAD: soil and plant analysis development; hereafter referred to as SPAD values) can indicate chlorophyll content and (2) whether chlorophyll content is positively correlated with root area and biomass production
Our results provide substantial evidence that SPAD values can serve as a good proxy of direct measurements of chlorophyll content at the species level

Summary

Introduction

Leaf stress tolerance potential either across 107 woody species or between functional types. Leaf chlorophyll content, measured directly on the basis of leaf area, significantly increased with SPAD values for shrubs (r = 0.698, n = 9, P = 0.027) and trees (r = 0.7903, n = 9, P = 0.011). Shrubs and trees exhibited the same LMA and leaf toughness; the palatability of leaves did not vary with functional types.

Results

Conclusion