Niklas, Karl J. , Cobb, Edward D. .
The hypothesis of diminishing returns: evidence from the scaling of specific leaf area.
Research indicates that increases in total leaf area (AT) may fail to keep pace with increases in total leaf mass (ML) across plants differing in size (e.g., as measured by stem diameter, D). This “diminishing returns” hypothesis predicts that the scaling exponent for AT vs. ML will be less than one and that the exponent for specific leaf mass (i.e., AT / ML) vs. D will be negative. These predictions were examined using data from 46 plants ranging in D between 0.125 cm and 0.485 m across 25 woody dicot species. Standardized major axis slopes were used to quantify scaling exponents and random effects model were used to quantify “species” and “size” effects on the numerical values of exponents. The exponents for AT vs. ML and AT / ML vs. D differed among species and different species-groupings. However, the exponent for AT vs. ML was generally less than one and the exponent for AT / ML vs. D was negative, as predicted. Random effects models indicated that “species” effects overshadowed “size” effects, although the latter variance component was statistically significant. The “diminishing returns” hypothesis therefore receives statistical support, i.e., although the numerical values of exponents are “species-dependent”, they are less than unity, as predicted by theory.
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1 - Cornell University, Department of Plant Biology, Ithaca, New York, 14853, (USA)
2 - Cornell University, Department of Plant Biology, Ithaca, NY, 14853, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Council Chambers/SUB
Date: Monday, July 28th, 2008
Time: 4:15 PM