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Titolo:
Shoot structure and photosynthetic efficiency along the light gradient in a Scots pine canopy
Autore:
Stenberg, P; Palmroth, S; Bond, BJ; Sprugel, DG; Smolander, H;
Indirizzi:
Univ Helsinki, Dept Forest Ecol, FI-00014 Helsinki, Finland Univ HelsinkiHelsinki Finland FI-00014 Ecol, FI-00014 Helsinki, Finland Oregon State Univ, Dept Forest Sci, Corvallis, OR 97331 USA Oregon State Univ Corvallis OR USA 97331 est Sci, Corvallis, OR 97331 USA Univ Washington, Coll Forest Resources, Seattle, WA 98195 USA Univ Washington Seattle WA USA 98195 est Resources, Seattle, WA 98195 USA Finnish Forest Res Inst, Suonenjoki Res Stn, FI-77600 Suonenjoki, Finland Finnish Forest Res Inst Suonenjoki Finland FI-77600 Suonenjoki, Finland
Titolo Testata:
TREE PHYSIOLOGY
fascicolo: 12-13, volume: 21, anno: 2001,
pagine: 805 - 814
SICI:
0829-318X(200108)21:12-13<805:SSAPEA>2.0.ZU;2-D
Fonte:
ISI
Lingua:
ENG
Soggetto:
CROWN ARCHITECTURE; NEEDLE MORPHOLOGY; DIRECT-RADIATION; ABIES AMABILIS; FLUX-DENSITY; SITKA SPRUCE; PICEA-ABIES; LEAF-AREA; INTERCEPTION; CONIFERS;
Keywords:
light interception; photosynthesis; Pinus sylvestris; shade acclimation;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Agriculture,Biology & Environmental Sciences
Citazioni:
36
Recensione:
Indirizzi per estratti:
Indirizzo: Stenberg, P Univ Helsinki, Dept Forest Ecol, POB 27, FI-00014 Helsinki, Finland Univ Helsinki POB 27 Helsinki Finland FI-00014 sinki, Finland
Citazione:
P. Stenberg et al., "Shoot structure and photosynthetic efficiency along the light gradient in a Scots pine canopy", TREE PHYSL, 21(12-13), 2001, pp. 805-814

Abstract

We examined the effects of structural and physiological acclimation on thephotosynthetic efficiency of Scots pine (Pinus sylvestris L.) shoots. We estimated daily light interception (DLI) and photosynthesis (DPHOT) of a number of sample shoots situated at different positions in the canopy. Photosynthetic efficiency (epsilon) was defined as the ratio of DPHOT to the potential daily light interception (DLIref) defined as the photosynthetically active radiation (PAR) intercepted per unit area of a sphere at the shoot location. To calculate DLIref, DLI and DPHOT, the radiation field surrounding a shoot in the canopy was first modeled using simulated directional distributions of incoming PAR on a clear and an overcast day, and estimates of canopy gap fraction in different directions provided by hemispherical photographs. A model of shoot geometry and measured data on shoot structure and photosynthetic parameters were used to simulate the distribution of PAR irradiance on the needle surface area of the shoot. Photosynthetic efficiency (epsilon) was separated into light-interception efficiency(epsilon (1) = DLI/DLIref),) and conversion efficiency (epsilon (PHOT) = DPHOT/DLI). This allowed us to quantify separately the effect of structural acclimation on the efficiency of photosynthetic light capture (epsilon (1)), and the effect of physiological acclimation on conversion efficiency (epsilon (PHOT)). The value of epsilon increased from the top to the bottom of the canopy. The increase was largely explained by structural acclimation (higher epsilon(1)) of the shade shoots. The value of epsilon (PHOT) of shade foliage wassimilar to that of sun foliage. Given these efficiencies, the clear-day value of DPHOT for a sun shoot transferred to shade was only half that of a shade shoot at its original position. The method presented here provides a tool for quantitatively estimating the role of acclimation in total canopy photosynthesis.

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Documento generato il 28/09/20 alle ore 14:12:12