Key canopy traits drive forest productivity

Quantifying the mechanistic links between carbon fluxes and forest canopy attributes will advance understanding of leaf-to-ecosystem scaling and its potential application to assessing terrestrial ecosystem metabolism. Important advances have been made, but prior studies that related carbon fluxes to multiple canopy traits are scarce. Herein, presenting data for 128 cold temperate and boreal forests across a regional gradient of 600 km and 5.4°C (from 2.4°C to 7.8°C) in mean annual temperature, I show that stand-scale productivity is a function of the capacity to harvest light (represented by leaf area index, LAI), and to biochemically fix carbon (represented by canopy nitrogen concentration, %N). In combination, LAI and canopy %N explain greater than 75 per cent of variation in above-ground net primary productivity among forests, expressed per year or per day of growing season. After accounting for growing season length and climate effects, less than 10 per cent of the variance remained unexplained. These results mirror similar relations of leaf-scale and canopy-scale (eddy covariance) maximum photosynthetic rates to LAI and %N. Collectively, these findings indicate that canopy structure and chemistry translate from instantaneous physiology to annual carbon fluxes. Given the increasing capacity to remotely sense canopy LAI, %N and phenology, these results support the idea that physiologically based scaling relations can be useful tools for global modelling.

[1]  A. Arneth,et al.  Nitrogen controls plant canopy light-use efficiency in temperate and boreal ecosystems , 2008 .

[2]  Peter B. Reich,et al.  Leaf structure (specific leaf area) modulates photosynthesis–nitrogen relations: evidence from within and across species and functional groups , 1998 .

[3]  John Pastor,et al.  Aboveground Production and N and P Cycling Along a Nitrogen Mineralization Gradient on Blackhawk Island, Wisconsin , 1984 .

[4]  F. Woodward,et al.  Terrestrial Gross Carbon Dioxide Uptake: Global Distribution and Covariation with Climate , 2010, Science.

[5]  S. T. Gower,et al.  A cross‐biome comparison of daily light use efficiency for gross primary production , 2003 .

[6]  P. Reich,et al.  FIRE AND VEGETATION EFFECTS ON PRODUCTIVITY AND NITROGEN CYCLING ACROSS A FOREST-GRASSLAND CONTINUUM , 2001 .

[7]  J. L. Parra,et al.  Very high resolution interpolated climate surfaces for global land areas , 2005 .

[8]  S. Ollinger,et al.  DIRECT ESTIMATION OF ABOVEGROUND FOREST PRODUCTIVITY THROUGH HYPERSPECTRAL REMOTE SENSING OF CANOPY NITROGEN , 2002 .

[9]  S. T. Gower,et al.  Direct and Indirect Estimation of Leaf Area Index, fAPAR, and Net Primary Production of Terrestrial Ecosystems , 1999 .

[10]  Sean C. Thomas,et al.  The worldwide leaf economics spectrum , 2004, Nature.

[11]  Andrew D Richardson,et al.  Near-surface remote sensing of spatial and temporal variation in canopy phenology. , 2009, Ecological applications : a publication of the Ecological Society of America.

[12]  S. Frolking,et al.  Canopy nitrogen, carbon assimilation, and albedo in temperate and boreal forests: Functional relations and potential climate feedbacks , 2008, Proceedings of the National Academy of Sciences.

[13]  D. F. Grigal,et al.  INFLUENCE OF LOGGING, FIRE, AND FOREST TYPE ON BIODIVERSITY AND PRODUCTIVITY IN SOUTHERN BOREAL FORESTS , 2001 .

[14]  P. Ciais,et al.  Influence of spring and autumn phenological transitions on forest ecosystem productivity , 2010, Philosophical Transactions of the Royal Society B: Biological Sciences.

[15]  Hiroyuki Muraoka,et al.  Satellite Ecology (SATECO)—linking ecology, remote sensing and micrometeorology, from plot to regional scale, for the study of ecosystem structure and function , 2008, Journal of Plant Research.

[16]  M. Schaepman,et al.  Intercomparison, interpretation, and assessment of spring phenology in North America estimated from remote sensing for 1982–2006 , 2009 .

[17]  W. Cohen,et al.  Site‐level evaluation of satellite‐based global terrestrial gross primary production and net primary production monitoring , 2005 .

[18]  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.

[19]  R. Waring,et al.  A generalised model of forest productivity using simplified concepts of radiation-use efficiency, carbon balance and partitioning , 1997 .

[20]  J. Aber,et al.  Primary production and nitrogen allocation of field grown sugar maples in relation to nitrogen availability , 1985 .

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

[22]  S. Gower,et al.  Interrelationships among the edaphic and stand characteristics, leaf area index, and aboveground net primary production of upland forest ecosystems in north central Wisconsin , 1997 .

[23]  Richard H. Waring,et al.  Environmental Limits on Net Primary Production and Light‐Use Efficiency Across the Oregon Transect , 1994 .

[24]  Ian J. Wright,et al.  Leaf phosphorus influences the photosynthesis–nitrogen relation: a cross-biome analysis of 314 species , 2009, Oecologia.

[25]  M. Monsi,et al.  On the factor light in plant communities and its importance for matter production. 1953. , 2004, Annals of botany.

[26]  J. Aber,et al.  Fine Roots, Net Primary Production, and Soil Nitrogen Availability: A New Hypothesis , 1985 .

[27]  Stephen Sitch,et al.  Variations in Amazon forest productivity correlated with foliar nutrients and modelled rates of photosynthetic carbon supply , 2011, Philosophical Transactions of the Royal Society B: Biological Sciences.

[28]  Steven W. Running,et al.  Remote sensing of temperate coniferous forest leaf area index The influence of canopy closure, understory vegetation and background reflectance , 1990 .

[29]  T. A. Black,et al.  Photosynthetic light use efficiency of three biomes across an east–west continental-scale transect in Canada , 2006 .

[30]  T. A. Black,et al.  A model‐data intercomparison of CO2 exchange across North America: Results from the North American Carbon Program site synthesis , 2010 .

[31]  J. Monteith.  Climate and the efficiency of crop production in Britain , 1977 .

[32]  John E. Erickson,et al.  Foliar morphology and canopy nitrogen as predictors of light-use efficiency in terrestrial vegetation , 2003 .

[33]  Maosheng Zhao,et al.  Drought-Induced Reduction in Global Terrestrial Net Primary Production from 2000 Through 2009 , 2010, Science.

[34]  Stephen Porder,et al.  Relationships among net primary productivity, nutrients and climate in tropical rain forest: a pan-tropical analysis. , 2011, Ecology letters.

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

[36]  C. Blyth.  On Simpson's Paradox and the Sure-Thing Principle , 1972 .