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Growth Responses of 53 Open‐Pollinated Loblolly Pine Families to Ozone and Acid Rain
Author(s) -
McLaughlin S. B.,
Layton P. A.,
Adams M. B.,
Edwards N. T.,
Hanson P. J.,
O'Neill E. G.,
Roy W. K.
Publication year - 1994
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq1994.00472425002300020005x
Subject(s) - ozone , shoot , acid rain , biomass (ecology) , zoology , loblolly pine , horticulture , chemistry , botany , pinus <genus> , biology , agronomy , ecology , organic chemistry
Field exposures of 9950 containerized 12‐wk‐old loblolly pine ( Pinus taeda L.) seedlings representing 53 commercially important, open‐pollinated families were conducted to evaluate individual and interactive effects of acid rain and O 3 on growth response. A 36‐plot field research facility comprised of 33 open‐top chambers and three open plots was used to test effects of five O 3 levels that included ambient (A) and seasonally integrated levels that were 0.53, 1.10, 1.58, or 2.15 times ambient. Individual effects of three levels of simulated acid rain (pH 3.3, 4.5, and 5.2) as well as their interaction with O 3 at 0.53A, 1.58A, and 2.15A levels were also included. Exposure to ambient air reduced average growth in height (26%), diameter (5%), and volume (14%) compared with growth of seedlings exposed to a 47% lower dose in charcoal filtered (CF) air. Responses to increasing O 3 above ambient levels varied widely between families, became increasingly inhibitory at the highest O 3 levels, but did not significantly exceed growth reductions found in ambient air. Diameter growth was reduced in most families by all levels of O 3 addition. Acid rain caused a general stimulation of height growth at ambient levels (pH 4.5), while both height and diameter growth were reduced at a mean pH of 3.3. Significant antagonism between rainfall acidity and O 3 effects on height and biomass increment was detected with increasing pollutant concentrations. Ozone reduced root/shoot biomass in most families, while acid rain did not.