Leon S. Dochinger

RELATIONSHIP OF SEED SOURCE AND DEVELOPMENTAL STAGE TO THE OZONE TOLERANCE OF ACER RUBRUM SEEDLINGS

Abstract Significant variation in tolerance to ozone (75 pphm) was expressed among red maple seedling progenies from four seed sources. Differences in seedling response occurred in extent of injury but not in type of injury. Seedlings from an Alabama source showed the least average foliar injury and least suppression of leaf growth after exposure to ozone in four stages of growth and four stages of leaf development. These Alabama seedlings also exhibited the largest increase in height growth after each of the four fumigations. Foliar injury and suppression of leaf growth was greatest in Pennsylvania and Minnesota seedlings. Despite a high degree of foliar damage, the Pennsylvania progeny showed significant retardation of growth in only one plant-growth stage, when seedlings were youngest. In all sources and in all plant-growth stages, the youngest (

Response of eastern hardwood species to ozone, sulfur dioxide and acid precipitation

Recent reports and observations of dieback, declines, and reduced growth in forests in the Eastern States have lead to an attempt to determine if atmospheric deposition is a major causal factor in these disorders. In the red spruce and southern pine forest where these abnormalities are either visible or have been documented by research data, studies are underway to determine the mechanisms involved and the role of atmospheric deposition. In the eastern hardwood forest there are reasons to suspect similar phenomenon, but because of the more complex nature and the wider species diversity in these forests the declines are more difficult to document. Another factor that increases the difficulty in determining whether atmospheric deposition is affecting hardwood forests is that tree responses to most stress factors, including atmospheric deposition, are very similar. The objective of this study was to determine the relative sensitivity and symptom development of 10 hardwood tree species to ambient levels of common gaseous pollutants.

Effects of roadside deicer salts and ozone on red maple progenies

Abstract Significant differences were found among three red maple progenies in their height growth response to salt, to ozone and to salt and ozone combined. Seedlings from a Maine seed source showed the lowest degree of foliar injury in response to all treatments and were also least suppressed in their total height growth. Demonstrated genetic tolerance or susceptibility of red maple to ozone and salt supports the validity of selection programmes for trees capable of withstanding pollution-related stresses.

Responses of hybrid poplar cuttings to chronic and acute levels of ozone

Hybrid poplar cuttings were exposed to either 0·15 ppm ozone for 6 weeks or 1 ppm ozone for 2, 4, or 8 h. The chronic ozone treatment reduced growth by 50% and caused injury to 75 of the leaves. The acute ozone treatment had no effect on growth but caused injury to 70% of the leaves 48 h after fumigation.

The Impact of Air Pollution On Eastern White Pine: The Chlorotic Dwarf Disease

Chlorotic dwarf is a serious disorder of eastern white pine (Pinus strobus L) in young plantations. Diseased trees are stunted and possess only current mottled foliage. Investigations into this problem were to define its symptomatology and etiology and to develop measures for control. Previous work had shown that susceptibility to chlorotic dwarf is genetically controlled and that the disease results from an aerological agent acting directly upon the foliage. By controlling the atmospheres around chlorotic dwarf field trees, evidence was obtained to prove that chlorotic dwarf is effected by the injury of gaseous dispersoids on the foliage of susceptible individuals.

First international symposium on acid precipitation and the forest ecosystem

These Proceedings report on the results of The First International Symposium on Acid Precipitation and the Forest Ecosystem which was held at The Ohio State University, Columbus, Ohio, U.S.A., on May 12-15, 1975. The Symposium focused on four related topics: (1) atmospheric chemistry, transport and precipitation; and effects of acidic precipitation on (2) aquatic ecosystems, (3) forest soils, and (4) forest vegetation.

Effects of chronic and acute exposure to sulphur dioxide on the growth of hybrid poplar cuttings

Abstract Hybrid poplar clones were fumigated in controlled-environment chambers with either 5 ppm sulphur dioxide for 1 1 2 , 3, and 6 h or with 0·25 ppm sulphur dioxide for six weeks. Multivariate analyses were made from shoot-growth data before and after treatment and on the foliar injury induced by SO 2 . Both short- and long-term fumigation produced similar plant-behaviour responses to the two SO 2 concentrations.

Responses of Hybrid Poplar Trees to Sulfur Dioxide Fumigation

This paper verifies the presence of significant interclonal variation in the tolerance of hybrid poplar (Populus deltoides Bartr. cv. Angulata × P. trichocarpa Torr. and Gray) to sulfur dioxide fumigation. Rooted stem cuttings of four hybrid poplar clones were exposed to 5 ppm sulfur dioxide for 0, 3, 6, 9, or 12 hours in controlled environment chambers. Multivariate analyses were made from the shoot growth measurements recorded for 4 weeks before and after fumigation and on the data of foliar injury induced by sulfur dioxide. The following factors were statistically significant in determining growth response and foliar injury: (1) genotype; (2) duration of treatment; and (3) interaction between genotype and hours of fumigation. All partial correlations between foliar injury and subsequent shoot growth were positive and significant. Sufficient genetic variation appears to exist in this Populus hybrid to encourage selection of clones tolerant to short-term exposures of high levels of sulfur dioxide.