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SHOOT STRUCTURAL EFFECTS ON NEEDLE TEMPERATURES AND PHOTOSYNTHESIS IN CONIFERS
Author(s) -
Smith William K.,
Carter Gregory A.
Publication year - 1988
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/j.1537-2197.1988.tb13467.x
Subject(s) - picea engelmannii , abies lasiocarpa , biology , shoot , photosynthesis , pinus contorta , botany , horticulture
Greater needle packing (number of needles per unit stem length) among shoots of Picea engelmannii (Parry ex. Engelm.), Abies lasiocarpa ([Hook] Nutt.), and Pinus contorta (Engelm.) collected at sun‐exposed locations resulted in leaf temperatures (T 1 ) that were well above air temperature (T a ) and which were closer to optimum for maximum photosynthesis under field conditions. Maximum photosynthesis in these species occurred at leaf temperatures well above mean maximum T a during most of the summer growth period. An approximate doubling in needle packing on sun shoots of these species, however, led to an estimated temperature enhancement of daily photosynthetic carbon gain of 21 to 36% compared to estimations assuming T 1 = T a for the entire day. Elevated T 1 due to needle packing may lead to substantial increases in summer carbon gain for conifers experiencing cold‐limited, short growth seasons.