Journal Article

Altitudinal differences in the leaf fitness of juvenile and mature alpine spruce trees (<i>Picea crassifolia</i>)

Changming Zhao, Litong Chen, Fei Ma, Buqing Yao and Jianquan Liu

in Tree Physiology

Volume 28, issue 1, pages 133-141
Published in print January 2008 | ISSN: 0829-318X
Published online January 2008 | e-ISSN: 1758-4469 | DOI: http://dx.doi.org/10.1093/treephys/28.1.133
Altitudinal differences in the leaf fitness of juvenile and mature alpine spruce trees (Picea crassifolia)

Show Summary Details

Preview

In many plant species, leaf morphology varies with altitude, an effect that has been attributed to temperature. It remains uncertain whether such a trend applies equally to juvenile and mature trees across altitudinal gradients in semi-arid mountain regions. We examined altitude-related differences in a variety of needle characteristics of juvenile (2-m tall) and mature (5-m tall) alpine spruce (Picea crassifolia Kom.) trees growing at altitudes between 2501 and 3450 m in the Qilian Mountains of northwest China. We found that stable carbon isotope composition (δ13C), area- and mass-based leaf nitrogen concentration (Na, Nm), number of stomata per gram of nitrogen (St/N), number of stomata per unit leaf mass (St/LM), projected leaf area per 100 needles (LA) and leaf mass per unit area (LMA) varied nonlinearly with altitude for both juvenile and mature trees, with a relationship reversal point at about 3100 m. Stomatal density (SD) of juvenile trees remained unchanged with altitude, whereas SD and stomatal number per unit length (SNL) of mature spruce initially increased with altitude, but subsequently decreased. Although several measured indices were generally found to be higher in mature trees than in juvenile trees, Nm, leaf carbon concentration (Cm), leaf water concentration (LWC), St/N, LA and St/LM showed inconsistent differences between trees of different ages along the altitudinal gradient. In both juvenile and mature trees, δ13C correlated significantly with LMA, Nm, Na, SNL, St/LM and St/N. Stomatal density, LWC and LA were only significantly correlated with δ13C in mature trees. These findings suggest that there are distinct ecophysiological differences between the needles of juvenile and mature trees that determine their response to changes in altitude in semi-arid mountainous regions. Variations in the fitness of forests of different ages may have important implications for modeling forest responses to changes in environmental conditions, such as predicted future temperature increases in high altitude areas associated with climate change.

Keywords: altitude; carbon isotope; ecophysiology; morphology; tree age

Journal Article.  0 words. 

Subjects: Plant Sciences and Forestry

Full text: subscription required

How to subscribe Recommend to my Librarian

Users without a subscription are not able to see the full content. Please, subscribe or login to access all content.