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Radiative transfer modeling of direct and diffuse sunlight in a Siberian pine forest

By P. B. Alton, P. North, Jörg Kaduk and Sietse O. Los


We have expanded the Monte Carlo, ray-tracing model FLIGHT in order to simulate photosynthesis within three-dimensional, heterogeneous tree canopies. In contrast to the simple radiative transfer schemes adopted in many land-surface models (e.g., the Big Leaf approximation), our simulation calculates explicitly the leaf irradiance at different heights within the canopy and thus produces an accurate scale-up in photosynthesis from leaf to canopy level. We also account for both diffuse and direct sunlight. For a Siberian stand of Scots pine Pinus sylvestris, FLIGHT predicts observed carbon assimilation, across the full range of sky radiance, with an r.m.s. error of 12%. Our main findings for this sparse canopy, using both measurements and model, are as follows: (1) Observationally, we detect a light-use efficiency (LUE) increase of only ≤10% for the canopy when the proportion of diffuse sky radiance is 75% rather than 25%. The corresponding enhancement predicted by our simulations is 10–20%. With such small increases in LUE, our site will not assimilate more carbon on overcast days compared to seasonally equivalent sunny days; (2) the scale-up in photosynthesis from top-leaf to canopy is less than unity. The Big Leaf approximation, based on Beer's law and light-acclimated leaf nitrogen, overpredicts this scale-up by ≥60% for low sky radiance (≤500 μmolPAR m−2 s−1); (3) when leaf nitrogen is distributed so as to maximize canopy photosynthesis, the increase in the canopy carbon assimilation, compared with a uniform nitrogen distribution, is small (≅4%). Maximum assimilation occurs when the vertical gradient of leaf nitrogen is slightly shallower than that of the light profile

Publisher: American Geophysical Union (AGU)
Year: 2005
DOI identifier: 10.1029/2005JD006060
OAI identifier:

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  11. (2002). Annual ecosystem respiration budget for a Pinus sylvestris stand in central Siberia, doi
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  13. (1994). Carbon dioxide exchange between an undisturbed old-growth temperate forest and the atmosphere, doi
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  19. (2002). Fire and site type effects on the long-term carbon and nitrogen balance in pristine Siberian Scots pine forests,
  20. (2001). Global dimming: a review of the evidence for a widespread and significant reduction in global radiation with discussion of it probable causes and possible agricultural consequences, doi
  21. (1998). Influence of volcanic eruptions on Northern Hemisphere summer temperature over the past 600 year,
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  23. (2003). Leaf size and angle vary widely across species: what consequences for light interception?, doi
  24. (2001). Modeling canopy CO2 fluxes: Are ’big-leaf’ simplifications justified?, doi
  25. (2000). Monte Carlo methods in optical canopy reflectance modeling, Remote Sens. doi
  26. (2002). Observed reductions of surface solar radiation at sites in the United States and worldwide from doi
  27. (2001). On the direct effect of clouds and atmospheric particles on the productivity and structure of vegetation, doi
  28. (1998). Parameterization and testing of a coupled photosynthesis-stomatal conductance model for boreal trees, doi
  29. (1991). Physiological and environmental regulation of stomatal conductance, photosynthesis and transpiration: A model that includes laminar boundary layer, doi
  30. (2003). Pinatubo, diffuse light and the carbon cycle, doi
  31. (1997). Profiles of photosynthetically active radiation, nitrogen and photosynthetic capacity in the boreal forest; implications for scaling from leaf to canopy, doi
  32. (1994). Relationships amoung maximum stomatal conductance, ecosystem surface conductance, carbon assimilation rate and plant nitrogen nutrition: A global ecology scaling exercise, doi
  33. (2004). Remote sensing in BOREAS: Lessons learned, Remote Sens. doi
  34. (2001). Remote sensing of canopy light-use efficiency using the photochemical reflectance index: Model and sensitivity analysis, Remote Sens. doi
  35. (2003). Respone of a deciduous forest to the Mount Pinatubo eruption: Enhanced photosynthesis, doi
  36. (1995). Scaling carbon dioxide and water vapour exchange from leaf to canopy in a temperate deciduous forest I. doi
  37. (2002). Seasonal and annual variations in the photosynthetic productivity and carbon balance of a central Siberian pine forest, doi
  38. (1997). Simple scaling of photosynthesis from leaves to canopies without the errors of big-leaf models, doi
  39. (2003). Simulated variations in atmospheric CO2 over a Wisconsin forest using a coupled ecosystem-atmosphere model, doi
  40. (1980). The angular distribution and interception of diffuse solar radiation below overcast skies, doi
  41. (1999). The propogation of foliar biochemical absorption features in forest canopy reflectance: A theoretical analysis, Remote Sens. doi
  42. (2004). The radiation transfer model intercomparison (RAMI) doi
  43. (1996). Three-dimensional forest light interaction model using a monte carlo method, doi
  44. (2001). Uncertainties in global terrestrial biosphere modeling, Part I: A comprehensive sensitivity analysis with a new photosynthesis and energy balance scheme, doi
  45. (2002). Uncertainties in the role of land vegetation in the carbon cycle, doi
  46. (2001). Variation in measured values of photosynthetic quantum yield in ecophysiological studies, doi
  47. (2000). Vertical gradients in photosynthetic light response within an old-growth douglas-fir and western hemlock canopy, doi

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