Long-term growth patterns of red spruce (Picea rubens Sarg.) were analyzed from increment cores collected from over 1000 trees at 48 sites in the eastern United States. Principal objectives were the evaluation of the distribution, timing, and uniqueness of observed patterns of decreasing radial growth during the past 25 years and the examination of stand competition and climate as factors contributing to observed changes.Our analyses focused on historical records of spruce mortality and approximately 200 years of radial growth data to search for historical precedents for current trends. In this work we have used time series analysis to detect the temporal frequency of significant negative or positive shifts in radial growth rates, an analysis of relationships between a stand competition index and observed changes in growth and mortality, and modeling of past growth-climate relationships to determine whether recent growth changes could be predicted based on climate.Collectively, these analyses indicate that the observed growth decreases of surviving red spruce trees at northeastern sites with high mortality have been anomalous during the past 20 to 25 years with respect to both historical annual growth patterns and past relationships to climate or stand development at these sites. In general, reductions in radial increment that have also been noted at southern high elevation sites but not at low elevations occurred 5 to 10 years later than at northern sites and represent less substantive departures from growth trends predicted by linear climate models.These results suggest that regional and not local stresses have triggered the observed decline in radial growth of red spruce at these sites. While climatic change may have contributed to observed changes, the degree of radial growth suppression observed is greater than would be expected based on past growth-climate relationships. This unique relationship of growth to climate suggests the influences of either recent, unique combinations of climatic stresses or the possibly interactive intervention of other regional-scale stresses, such as atmospheric pollution.

Summary 1.In mountainous regions, road construction is accompanied by large-scale physical disturbance associated with cut and fill operations that drastically alter the landscape. Cut operations remove soil and rock from the hillside above the proposed road, while soil and rock are deposited on the down-slope area in fill operations. The resultant roadsides are highly disturbed habitats characterized by plant communities maintained at an early successional stage. They are often planted with non-native species and frequently provide vectors for the introduction and spread of invasive species. Public transportation managers need to balance the rapid revegetation of roadsides with the goal of maximizing use of native species and minimizing the introduction of non-native species. 2. This study examined vegetation-site relationships along 13 major four-lane highways in West Virginia, USA, using analysis of variance, multiresponse permutation procedures and indicator species analysis. 3. Mean soil nutrient values showed some differences with respect to highway, but fewer when highway positions were compared. Similarly, when highway position was considered, there were no significant differences in mean plant species richness, evenness or diversity. 4. Results of multiresponse permutation procedures suggested that different highways may be characterized by distinct vegetation assemblages. This hypothesis was supported by indicator species analysis: 54 species showed a statistically significant ( P < 0·05) affinity to one highway over all others. More than half of these were classified as non-native and exotic invasive species. When highway position was considered, no significant differences in community composition were found, and indicator species analysis found only 25 species that exhibited a significant affinity to one type of position. Of these, only eight were exotic. 5. Of the 33 most abundant herbaceous species, 11 showed a significant relationship between cover and distance from pavement. For all but one, average cover declined in a linear fashion with increasing distance. 6. Synthesis and applications . Despite extensive topographic disturbance associated with highway construction, the resultant vegetative communities do not differ with respect to type of construction or resultant landform. This suggests that highway agencies can manage roadside vegetation using similar, standard techniques. Roadsides are optimal growing sites for exotic invasive species that out-compete native vegetation. Management goals should therefore include techniques for limiting the establishment of these species, and substitution of non-native species planted for erosion control with suitable native species.

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Old-growth stands of red spruce (Picea rubens) were sampled at the only four localities in the mountains of southwestern Virginia and central West Virginia where examples of such are known to exist. Based upon mean ages (+ SE) of cored trees, sampled stands ranged in age from 164 + 18 to 201 + 10 yr. Dendro-ecological (tree-ring) analysis showed a marked decline in growth of trees at three localities during the late 1800s, followed by recovery to previous levels of growth within two decades. This growth-trend decline generally coincides with a period of extensive mortality of red spruce reported to have occurred in central West Virginia. Basal area of trees > 2.5 cm DBH ranged from 35.4 to 46.1 mZ/ha. These figures are considerably lower than those recorded at earlier dates for similar old-growth stands in the Appalachians, which suggests that a general decline has occurred over the last half-century.

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