Sources of within- and between-stand variability in specific leaf area of three ecologically distinct conifer species

Specific leaf area (SLA) is an important ecophysiological variable, but its variability within and between stands has rarely been simultaneously examined and modeled across multiple species. Extensive datasets on SLA in coastal Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirb.) Franco), hybrid spruce (Picea engelmannii Parry × Picea glauca (Moench) Voss × Picea sitchensis (Bong.) Carr.), and ponderosa pine (Pinus ponderosa Dougl. ex P. & C. Laws.) were used to estimate variability of SLA within a canopy and its relationship to tree- and stand-level covariates, and to predict SLA at various locations in tree crowns. Also, in the case of hybrid spruce, variation in SLA due to different relative horizontal lengths from the bole was examined. In all species, SLA systematically increased from tree tip to crown base and decreased with foliage age class. Cardinal direction did not have a highly significant influence in either Douglas-fir or hybrid spruce, but SLA did significantly decrease from branch tip to bole in hybrid spruce. Tree- and stand-level (e.g. density, site index) factors had relatively little influence on SLA, but stand age did have a significant positive influence. For ponderosa pine, a significant relationship between canopy mean current-year SLA and carbon isotope discrimination was also found, suggesting the importance of water stress in this species. An equation was fitted to estimate SLA at various points in the canopy for each species and foliage age class using absolute height in the canopy, relative vertical height in the tree, and stand age.RésuméLa surface spécifique des feuilles (SLA) est un paramètre écophysiologique important mais sa variabilité intra et inter-peuplements n’a jamais été examinée et modélisée sur des gammes larges d’espèces. Des jeux de données très détaillés de SLA de Douglas côtiers [Pseudotsuga menziesii var. menziesii (Mirb.) Franco], d’épicéas hybrides (Picea engelmannii Parry × Picea glauca (Moench) Voss × Picea sitchensis (Bong.) Carr), et de pins ponderosa (Pinus ponderosa Dougl. ex P. & C. Laws.) ont été mobilisés pour évaluer la variabilité de SLA dans une canopée. Les relations entre SLA et des covariables à l’échelle de l’arbre ou du peuplement ont été précisées, un modèle prédictif de SLA à différents niveaux dans les couronnes a été construit. Dans le cas de l’épicéa, l’impact de la distance de branche entre l’aiguille et le tronc a également été testé. Dans toutes les espèces, SLA augmentait systématiquement du sommet des arbres à la base de la couronne, et diminuait avec la classe d’âge des aiguilles. La direction cardinale n’avait guère d’influence sur SLA ni dans le cas du Douglas ni dans celui de l’épicéa; mais SLA diminuait systématiquement depuis l’extrémité des branches vers le tronc. Les facteurs arbre et peuplement (comme la densité, l’indice de productivité de la station) n’avaient que peu d’impact sur SLA alors que l’âge du peuplement avait un effet significatif et positif. Pour le pin ponderosa, une relation significative a été détectée entre la valeur moyenne de SLA des aiguilles de l’année et la discrimination isotopique du carbone, ce qui suggère l’impact des contraintes hydriques pour cette espèce. Un modèle de prédiction de SLA à différentes positions dans la canopée a été ajusté sur les données de chaque espèce et classe d’âge, en se basant sur la hauteur dans la canopée, la hauteur relative dans l’arbre et l’âge du peuplement.

[1]  Douglas A. Maguire,et al.  Influence of Swiss needle cast on foliage age-class structure and vertical foliage distribution in Douglas-fir plantations in north coastal Oregon , 2006 .

[2]  P. Reich,et al.  Relationships of leaf dark respiration to leaf nitrogen, specific leaf area and leaf life-span: a test across biomes and functional groups , 1998, Oecologia.

[3]  H. Sterba,et al.  Specific leaf area and needle weight of Norway spruce (Piceaabies) in stands of different densities , 1985 .

[4]  M. Greenwood,et al.  Canopy dynamics and the morphological development of Abies balsamea: effects of foliage age on specific leaf area and secondary vascular development. , 1995, Tree physiology.

[5]  Olevi Kull,et al.  An analysis of light effects on foliar morphology, physiology, and light interception in temperate deciduous woody species of contrasting shade tolerance. , 1998, Tree physiology.

[6]  S. Running,et al.  Regional‐Scale Relationships of Leaf Area Index to Specific Leaf Area and Leaf Nitrogen Content , 1994 .

[7]  D. Ellsworth,et al.  Dependence of needle architecture and chemical composition on canopy light availability in three North American Pinus species with contrasting needle length. , 2002, Tree physiology.

[8]  Ülo Niinemets,et al.  Effects of light availability and tree size on the architecture of assimilative surface in the canopy of Picea abies: variation in shoot structure , 1995 .

[9]  J. Marshall,et al.  Foliage height influences specific leaf area of three conifer species , 2003 .

[10]  H. Bartelink.  Allometric relationships on biomass and needle area of Douglas-fir , 1996 .

[11]  D. Hollinger.  Canopy organization and foliage photosynthetic capacity in a broad-leaved evergreen montane forest , 1989 .

[12]  D. Meidinger,et al.  Ecosystems of British Columbia , 1991 .

[13]  J. Roberts,et al.  Towards a predictive description of forest canopies from litter properties , 1999 .

[14]  N. Saliendra,et al.  Carbon Isotope Discrimination and Gas Exchange in Coffea arabica During Adjustment to Different Soil Moisture Regimes , 1992 .

[15]  P. Kupper,et al.  Spatial variation in sapwood area to leaf area ratio and specific leaf area within a crown of silver birch , 2006, Trees.

[16]  R. Ceulemans,et al.  Variation of specific leaf area and upscaling to leaf area index in mature Scots pine , 2006, Trees.

[17]  K. O’Hara,et al.  The influence of stand structure on ecophysiological leaf characteristics of Pinus ponderosa in western Montana , 2001 .

[18]  G. Farquhar,et al.  Some relationships between the biochemistry of photosynthesis and the gas exchange of leaves , 1981, Planta.

[19]  William E. Winner,et al.  Foliage physiology and biochemistry in response to light gradients in conifers with varying shade tolerance , 1999, Oecologia.

[20]  C. T. Dyrness,et al.  Natural Vegetation of Oregon and Washington , 1988 .

[21]  Han Y. H. Chen,et al.  Effects of light on growth, crown architecture, and specific leaf area for naturally established Pinuscontorta var. latifolia and Pseudotsugamenziesii var. glauca saplings , 1996 .

[22]  J. Kershaw,et al.  Crown structure in western hemlock, Douglas-fir, and grand fir in western Washington: horizontal distribution of foliage within branches , 1996 .

[23]  H. Temesgen,et al.  Leaf mass per area relationships across light gradients in hybrid spruce crowns , 2006, Trees.

[24]  D. Sprugel,et al.  Acclimation responses of mature Abies amabilis sun foliage to shading , 1994, Oecologia.

[25]  Douglas A. Maguire,et al.  Patterns in vertical distribution of foliage in young coastal Douglas-fir , 1996 .

[26]  R. Kennedy.  Causes and consequences of uncertainty in the application of a biogeochemical model to a large geographic region , 2004 .

[27]  W. Wykoff.  Measuring and modeling surface area of ponderosa pine needles , 2002 .

[28]  N. Scott,et al.  Specific leaf area and nitrogen distribution in New Zealand forests: Species independently respond to intercepted light , 2006 .

[29]  A. Richardson,et al.  Foliar plasticity of hybrid spruce in relation to crown position and stand age. , 2000 .

[30]  P. Reich,et al.  Canopy dynamics and aboveground production of five tree species with different leaf longevities. , 1993, Tree physiology.

[31]  D. Bates,et al.  Mixed-Effects Models in S and S-PLUS , 2001 .

[32]  B. Bond,et al.  Needle anatomy changes with increasing tree age in Douglas-fir. , 2002, Tree physiology.

[33]  Alan B. Berg,et al.  Specific Leaf Area of Douglas-fir Reproduction As Affected by Light and Needle Age , 1979 .

[34]  E. D. Ford,et al.  Variation in specific needle area of old-growth Douglas-fir in relation to needle age, within-crown position and epicormic shoot production. , 2002, Tree physiology.

[35]  P. Reich,et al.  Canopy structure and vertical patterns of photosynthesis and related leaf traits in a deciduous forest , 1993, Oecologia.

[36]  J. R. Evans.  Photosynthesis and nitrogen relationships in leaves of C3 plants , 2004, Oecologia.

[37]  B. Sutton,et al.  Analysis of Sitka spruce-interior spruce introgression in British Columbia using cytoplasmic and nuclear DNA probes , 1994 .

[38]  J. Marshall,et al.  Sources of variation in ecophysiological parameters in Douglas-fir and grand fir canopies. , 2003, Tree physiology.

[39]  J. Ehleringer,et al.  Carbon Isotope Discrimination and Photosynthesis , 1989 .

[40]  Ü. Niinemets,et al.  Acclimation to low irradiance in Picea abies: influences of past and present light climate on foliage structure and function. , 1997, Tree physiology.

[41]  Simon N. Wood,et al.  Generalized Additive Models , 2006, Annual Review of Statistics and Its Application.

[42]  S. Wood.  Generalized Additive Models: An Introduction with R , 2006 .

[43]  H. Temesgen,et al.  Bivariate distribution functions for predicting twig leaf area within hybrid spruce crowns , 2003 .

[44]  R. McMurtrie,et al.  Environmental constraints on the structure and productivity of pine forest ecosystems : a comparative analysis , 1994 .

[45]  J. Clair.  Genetic variation in tree structure and its relation to size in Douglas-fir. II: Crown form, branch characters, and foliage characters , 1994 .

[46]  A. Specht,et al.  Canopy structure in Eucalyptus-dominated communities in Australia along climatic gradients , 1989 .

[47]  Duncan Steil Wilson.  Soil-site productivity relationships of central Oregon ponderosa pine , 2003 .