Relationships among leaf traits of Australian arid zone plants: alternative modes of thermal protection

Publisher:
CSIRO Publishing
Publication Type:
Journal Article
Citation:
Australian Journal Of Botany, 2012, 60 (6), pp. 471 - 483
Issue Date:
2012-01
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Despite the importance of leaf traits that protect against critically high leaf temperatures, relationships among such traits have not been investigated. Further, while some leaf trait relationships are well documented across biomes, little is known about such associations within a biome. This study investigated relationships between nine leaf traits that protect leaves against excessively high temperatures in 95 Australian arid zone species. Seven morphological traits were measured: leaf area, length, width, thickness, leaf mass per area (LMA), water content, and an inverse measure of pendulousness (LP). Two spectral properties were measured: reflectance of visible and near infrared radiation. Three key findings emerged: 1) LP decreased (pendulousness increased) with leaf size and LMA, the former relationship suggesting that pendulousness affords thermal protection when leaves are large; 2) LMA increased with thickness and decreased with water content, indicating alternative means for protection through increasing thermal mass; 3) spectral reflectance increased with LMA and thickness and decreased with water content. The consistent co-variation of thermal protective traits with LMA, a trait not usually associated with thermal protection, suggests that these traits fall along the leaf economics spectrum, with leaf longevity increasing through protection not only against structural damage but also against heat stress.
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