, Volume 132, Issue 2, pp 188–196 | Cite as

Leaf area accumulation helps juvenile evergreen trees tolerate shade in a temperate rainforest

  • Christopher H. LuskEmail author


Most knowledge of the physiological correlates of interspecific variation in shade tolerance derives from studies of first-year seedlings in artificial environments. The present study relates growth, allocation, foliage turnover, biomass distribution and gas exchange traits to low-light survival of large seedlings (20–100 cm tall) of eight temperate rainforest evergreens under field conditions. Taxa for which natural mortality was not observed in low light during the 14-month study are referred to here as "shade-tolerant" species, and those which did die in the shade are referred to as "light-demanding" species. In low light (2–5% canopy openness), shade-tolerant species had slightly lower light compensation points than light-demanders. Light-demanding species had more plastic aboveground allocation patterns, generally allocating proportionally less aboveground biomass to foliage production than shade-tolerant associates in high light (>10% canopy openness), but more in low light. Foliage turnover was generally much slower in shade-tolerant species (10–40% year–1) than in light-demanding species (30–190%). As these differences in leaf retention outweighed variation in allocation, shade-tolerant species displayed higher leaf areas at all light levels. Furthermore, all shade-tolerant species gained leaf area in low light during the study period, whereas light-demanding taxa showed leaf area declines. Higher leaf area ratios, plus differences in light compensation points, indicate that large seedlings of shade-tolerant evergreens enjoy net carbon gain advantages over light-demanding associates in low light. However, minimal growth rate differences in low light imply higher storage allocation in shade-tolerant species. This study provides a rather different picture from that which has emerged from recent reviews of first-year seedling data, illustrating the long-term consequences of foliage turnover differences for biomass distribution, and suggesting that shade tolerance in juvenile evergreen trees is associated with a suite of traits which enhance net carbon gain, but not growth, in low light. Accumulation of a large foliage area through long leaf retention times is probably a key mechanism enhancing low-light carbon gain in evergreens.

Allocation Gas exchange Leaf area ratio Leaf longevity Relative growth rate 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

Copyright information

© Springer-Verlag 2002

Authors and Affiliations

  1. 1.Departamento de BotánicaUniversidad de ConcepciónConcepciónChile

Personalised recommendations