Interacting determinants of specific leaf area in 22 herbaceous species: effects of irradiance and nutrient availability

We measured specific leaf area (SLA) and six of its determinants (the thickness of lamina, mesophyll, epidermis, mid-vein and mid-vein support tissues and leaf water content) in a collection of 22 herbaceous species grown in factorial combinations of high μ1100 (mol m -2 s -1 ) and low (200) irradiance crossed with high (1: 1) and low (1: 6 dilution) concentrations of a modified Hoagland hydroponic solution. SLA increased with both decreasing irradiance and with increasing nutrient availability but there was a strong interaction between the two. Lamina and mesophyll thickness both increased with increasing irradiance and nutrient availability without any interaction. The experimental treatments had complicated effects on mid-vein thickness and its support tissues. Leaf water content (a measure of leaf tissue density) decreased with increasing irradiance levels and with decreasing nutrient supply, but with an interaction between the two treatments. Changes in nutrient supply had no effect on SLA at high irradiance because leaf thickness and leaf tissue density changed in a compensatory way. A path analysis revealed that each of the components affected SLA when the others were statistically controlled but the strengths of the effects of mesophyll thickness, mid-vein thickness and water content differed between treatment groups. The effect of epidermal thickness on SLA was constant across environments and it showed no significant covariation with the other determinants. There was significant covariation between mesophyll thickness, mid-vein thickness and water content and this covariation was constant across the treatment groups.

[1]  M. Canny.  Apoplastic Water and Solute Movement: New Rules for an Old Space , 1995 .

[2]  H. Lambers,et al.  Modelling of the responses to nitrogen availability of two Plantago species grown at a range of exponential nutrient addition rates , 1988 .

[3]  E. Garnier.  Growth analysis of congeneric annual and perennial grass species , 1992 .

[4]  P. Reich,et al.  From tropics to tundra: global convergence in plant functioning. , 1997, Proceedings of the National Academy of Sciences of the United States of America.

[5]  R. Wylie.  PRINCIPLES OF FOLIAR ORGANIZATION SHOWN BY SUN‐SHADE LEAVES FROM TEN SPECIES OF DECIDUOUS DICOTYLEDONOUS TREES , 1951 .

[6]  H. Poorter,et al.  The chemical composition and anatomical structure of leaves of grass species differing in relative growth rate , 1994 .

[7]  P. Lucas,et al.  Estimation of the fracture toughness of leaves , 1990 .

[8]  E. Garnier,et al.  Leaf anatomy, specific mass and water content in congeneric annual and perennial grass species , 1994 .

[9]  Christian Körner,et al.  Functional Morphology of Mountain Plants) , 1989 .

[10]  H. C. Hanson.  LEAF‐STRUCTURE AS RELATED TO ENVIRONMENT , 1917 .

[11]  M. Abrams,et al.  Leaf structural characteristics of 31 hardwood and conifer tree species in central Wisconsin: influence of light regime and shade-tolerance rank. , 1990 .

[12]  Peter M. Bentler,et al.  EQS : structural equations program manual , 1989 .

[13]  Driss Meziane.  Étude de la variation interspécifique de la vitesse spécifique de croissance et modélisation de l'effet des attributs morphologiques, physiologiques et d'allocation de biomasse , 1997 .

[14]  H. Lambers,et al.  Effects of nitrogen supply on the anatomy and chemical composition of leaves of four grass species belonging to the genus Poa, as determined by image‐processing analysis and pyrolysis–mass spectrometry , 1997 .

[15]  Kenneth A. Bollen,et al.  Structural Equations with Latent Variables , 1989 .

[16]  Christopher B. Field,et al.  photosynthesis--nitrogen relationship in wild plants , 1986 .

[17]  W. Smith,et al.  Associations between leaf structure, orientation, and sunlight exposure in five Western Australian communities. , 1998, American journal of botany.

[18]  Bill Shipley,et al.  Structured interspecific determinants of specific leaf area in 34 species of herbaceous angiosperms , 1995 .

[19]  K. Gabriel,et al.  The biplot graphic display of matrices with application to principal component analysis , 1971 .

[20]  D. Tilman.  Plant Strategies and the Dynamics and Structure of Plant Communities. (MPB-26), Volume 26 , 1988 .

[21]  J. P. Grime,et al.  Plant Strategies and Vegetation Processes. , 1980 .

[22]  Arthur Cronquist,et al.  Manual of Vascular Plants of Northeastern United States and Adjacent Canada , 2004 .

[23]  E. Garnier,et al.  Specific leaf area and leaf nitrogen concentration in annual and perennial grass species growing in Mediterranean old-fields , 1997, Oecologia.

[24]  H. Lambers,et al.  Evidence for optimal partitioning of biomass and nitrogen at a range of nitrogen availabilities for a fast- and slow-growing species , 1993 .

[25]  S. B. Carpenter,et al.  A comparative study of leaf thickness among southern Appalachian hardwoods , 1981 .

[26]  John Tenhunen,et al.  A model separating leaf structural and physiological effects on carbon gain along light gradients for the shade‐tolerant species Acer saccharum , 1997 .