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O 3 uptake and drought stress effects on carbon acquisition of ponderosa pine in natural stands
Author(s) -
Grulke NE,
Preisler HK,
Rose C,
Kirsch J,
Balduman L
Publication year - 2002
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1046/j.1469-8137.2002.00403.x
Subject(s) - photosynthesis , growing season , zoology , environmental science , botany , atmospheric sciences , biology , geology
Summary • The effect of O 3 exposure or uptake on carbon acquisition (net assimilation ( A ) or gross photosynthesis ( P g )), with and without drought stress, is reported here in 40‐yr‐old‐ponderosa pine ( Pinus ponderosa ) trees. • Maximum daily gas exchange was measured monthly for 12 trees at four sites differing in pollutant exposure over two growing seasons with above‐ and below‐average annual precipitation. Gas exchange measures were estimated between sampling periods using a generalized additive regression model. • Both A and P g generally declined with cumulative O 3 exposure or uptake at all sites. As a response variable, P g was slightly more sensitive than A to cumulative O 3 exposure. As a metric, O 3 uptake vs exposure permitted slightly better statistical resolution of seasonal response between sites. • The effect of late summer drought stress was statistically significant only at the moderate pollution site, and combined synergistically with O 3 exposure or uptake to reduce P g . The general additive model allows the user to define a deleterious level of cumulative O 3 exposure or uptake, and to quantitatively assess biological response.