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Direct Effects of Air Pollution on Forest Ecosystems of Western North America
1993
Peterson, D.L. (University of Washington, Seattle (USA))
Visible chlorotic injury and reduced foliar biomass are found in Pinus ponderosa and P. jefreyi in the mountains of southern California and the west slope of Sierra Nevada. Reduced tree growth and accelerated rates of forest succession has been documented in this area, with ozone resistant, shade tolerant species replacing P. ponderosa. There may also be some interactions among ozone, drought stress, insects and fungal pathogens.
Afficher plus [+] Moins [-]Direct Effects of Air Pollution on Physiology of Forest Trees in the Western United States
1993
Bytnerowicz, A. (USDA Forest Service, Riverside, CA (USA). Pacific Southwest Research Station)
Physiological processes of western trees are effected by ozone at concentration over 80 ppb, depending on the duration of the exposures and environmental conditions. At a single fascicle level short-term ozone exposures can cause reduction, no change or increase of stomatal conductance and net assimilation rate. Two seasons of exposures at twice level ozone concentrations caused a significant reduction of stomatal conductance and pigment concentrations in foliage.
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