Interactive Effects of Acid Rain and Gaseous Air Pollutants on Natural Terrestrial Vegetation.

摘要

This research is designed to identify concentration thresholds for individual and combined effects of acid rain and O sub 3 on growth and growth processes of both forest tree seedlings and lichens and to document the significance of changing patterns of deposition and/or mobilization of trace metals and nutrients in tree rings. Greenhouse studies have focused on effects of varying levels of rainfall acidity on growth (amount and distribution) and nutrient uptake efficiency of mycorrhizal and nonmycorrhizal seedlings of white oak and loblolly pine from soil nutrient pools. Results to date show significant diameter preduction in mycorrhizal infected white oak seedlings at pH 4.2, compared to pH 4.8. Combined effects of rainfall acidity (pH 4.0 and 5.0), mist acidity (pH 3.5 and 5.0), and ozone (0 and 0.12 ppM) and soil type on growth and physiology of red spruce in two soil types have also been examined. Preliminary results indicate no adverse effects of acid rain, acid mist, or ozone on seedling growth but significant differences in response of seedlings on different soil types. Studies of the uptake and distribution of trace metals in tree rings of shortleaf pine have documented increases in aluminum, cadmium, copper, iron, manganese, and zinc in recent decades which appear to reflect changing regional and/or local availability of those elements. 8 references, 2 figures, 3 tables. (ERA citation 10:014793)