Montane Spruce Research Articles

Occurrence of pollution-sensitive epiphytic lichens in woodlands affected by forest decline: a new hypothesis

Summary Influences of forest dieback on epiphytic lichen vegetation in montane spruce forests of the Harz Mountains (Northern Germany) are described. The epiphytic lichen vegetation of damaged forest stands consists of more species and a higher number of endangered, loss toxitolerant lichen taxa than that of intact forest stands. Therefore, we tested the hypothesis that concentrations of potentially phytotoxic substances in stem flow are lower in damaged stands than in intact stands, because the higher needle surface of the latter should result in a higher pollutant interception. In accordance with this hypothesis, lower concentrations of the elements S, Zn, AI, and Mn and of hydronium ions were established in the stem flow of a damaged stand compared to an intact stand under identical climatological conditions. This phenomenon could be a precondition of the higher lichen diversity in the damaged stand.

Acid rain and soils of the Adirondacks. III. Rates of soil acidification in a montane spruce–fir forest at Whiteface Mountain, New York

To assess the impact of atmospheric deposition on soil acidification and base cation supplies in montane spruce–fir forest soils at Whiteface Mountain, New York, base cation and proton fluxes were determined for organic and mineral horizons from measurements made at four stands (1020–1090 m above sea level) over a 4-year period. Our best estimates indicate an annual accumulation of H+ and a net loss of base cations from the forest floor of about 0.71 kmolc/ha, a 2.8% per year loss of the total forest floor base cation pool. This high rate of acidification is attributable to base cation leaching by sulfate and organic anions, and uptake by living biomass. From 1986 to 1990, the annual net loss rate of forest floor Ca, the most abundant base cation, was several times greater than historical loss rates as determined by 50-year comparisons of forest floor Ca in nearly identical forests of the Adirondack High Peaks region. Published data on long-term trends in Ca deposition in the U.S. Northeast suggest that the difference between historical and current net loss rates of forest floor Ca may be due to sharply reduced atmospheric inputs of Ca after about 1970, exacerbated by sulfate leaching. In mineral horizons where the total base cation pool (mostly mineral bound) is very large, the net losses of base cations were substantially lower and in the range where losses due to leaching and uptake can be countered by mineral weathering.

Modem pollen spectra from west central British Columbia

Sixty-four moss and organic litter samples were collected from five biogeoclimatic zones distributed from sea level on the central coast of British Columbia onto the western edge of the Interior Plateau at 1000 – 1900 m and analyzed for pollen and spores. Four of the five biogeoclimatic zones produced characteristic pollen and spore spectra. The coastal western hemlock biogeoclimatic zone is characterized by Tsuga heterophylla, Alnus, and Cupressaceae. Significant levels of nonarboreal pollen (NAP), mainly Lysichiton and fern spores, occur in some sites. Interior Douglas-fir zone samples are dominated by Pseudotsuga and Tsuga heterophylla with notable Betula, Cupressaceae, and Alnus. Pinus pollen becomes the dominant type at the eastern margins of the interior Douglas-fir zone and dominates the Engelmann spruce – subalpine fir, montane spruce, and sub-boreal pine–spruce biogeoclimatic zones at high and intermediate elevations to the east. In the Engelmann spruce – subalpine fir zone, Abies pollen is characteristically more abundant than Picea, and notable percentages of NAP, especially Artemisia, occur. In the transition from Engelmann spruce – subalpine fir zone to montane spruce zone, Abies and Picea percentages are about equal or Picea predominates slightly, whereas in the montane spruce zone and sub-boreal pine spruce zones, Picea values exceed Abies values often four to five times. Percent pollen and spore versus percent taxon cover diagrams, despite widely spread values, reveal general relationships and background pollen rain values for major taxa valuable to the interpretation of fossil pollen assemblages. Pinus is greatly overrepresented with a regional background of 10–15%. At low to intermediate cover values, Tsuga heterophylla, Pseudotsuga, and Cupressaceae are represented more or less as they occur in the vegetation, with regional backgrounds up to 5%. Picea and Abies are underrepresented, with regional background value of 0–3%. Key words: pollen, surface spectra, biogeoclimatic zones, species cover, British Columbia.

Size-specific mortality, growth, and structure of a Great Smoky Mountains red spruce population

Old-growth population dynamics of Picearubens Sarg. were studied in a montane spruce–fir forest in North Carolina and Tennessee. Size-class structure fit a semilogarithmic rotated sigmoid curve typical of a stable population. Although the population contained trees of all ages, a large proportion of the population was less than 100 years old; few trees were greater than 350 years old. Mortality rates were estimated from a 2-decade census and from population structure data. For trees above breast height, annual mortality was approximately 1% of the population. Small trees (<30 cm dbh) and large trees (>60 cm dbh) had mortality rates exceeding 0.7% per year. Intermediate-sized trees tended to have low mortality rates (<0.5% per year) and high radial growth rates. Growth in the 10-year interval preceding death tended to be slow for standing dead trees. Standing death of canopy trees was more prevalent than death by windfall. These findings emphasized the influence of stand dynamics on spruce growth and mortality.

Cold-induced dieback of montane spruce forests in the Swedish Scandes - a modern analogue of paleoenvironmental processes.

In 1987 particularly, but also in 1988, primaeval montane coniferous forests of northern Scandinavia experienced needle loss on an unprecedented scale, which affected the character of the entire landscape in certain regions. This study elucidates the dieback event For Norway spruce [Picea abies (L.) Karst.] in an area of the Swedish Scandes. The study includes visual assessment of percentage needle loss, age structure, radial growth and various environmental parameters, along altitudinal transects and within a larger sample plot. Frequency and magnitude of foliage damage were found to be related to elevation. The dieback process of closed forest stands was interpreted as a response to short-term climatic variability. Damage mainly developed during one of the coldest early winters (December January 1986/7) of this century. In combination with sub-normal depth of the snow caver, the severe cold promoted exceptionally deep and persistent soil frost in spruce forest stands. It is hypothesized that damage was mainly due to winter/spring drought (frost-drought). Phenotypically closed forest stands may change in just a few years in response to cooling, a feature which has not been realized previously. The possibility of major retrogressive responses lo short-term climatic events should therefore be considered in studies of historical biogeography and when modelling vegetation succession. The forest studied was probably established after a severe wind storm in 1837. The restocking process was facilitated by the post-Little Ice Age warming, but the stands are at present suffering severe dieback due to the recent cooling of the climate. The results stress the potential importance of short-term climatic disturbance in boreal forest succession. Reasonably, rapid cold-induced dieback of forest stands may have been a recurrent feature of Holocene forest history in the Boreal zone.

Relationship of Growth Reduction in Douglas-fir to Infection by Armillaria Root Disease in Southeastern British Columbia

Bloomberg, W. J., and Morrison, D. J. 1989. Relationship of growth reduction in Douglas-fir to infection by Armillaria root disease in southeastern British Columbia. Phytopathology 79:482-487. Stem volume growth during consecutive 5-yr periods was measured in were greatest for the past 5-yr period and least, though still significant, for four Douglas-fir (Pseudotsuga menziesii) stands infected by Armillaria the past 15-yr period. Trends during the past 30 yr showed greater declines ostoyae in the interior cedar-hemlock and montane spruce biogeoclimatic in severity classes 3 and 4 relative to class 0 than in classes 1 and 2. The zones of southeastern British Columbia. Growth, expressed as percent of period in which decline was initiated also occurred earlier (up to 25 yr ago) stem volume at the start of each period, decreased significantly as resinosis in classes 3 and 4 than in other classes. The percentage of basal increased due to mycelial colonization of the tree base. It was highest in circumference that was affected by lesion was strongly related to percent resinosis severity class 0 (healthy), lowest in classes 3 (> 50-100% of basal roots infected but only weakly to percent volume growth. The relation of circumference showing resinosis) and 4 (recently killed, 100% resinosis), percent basal circumference affected by lesion to percent volume growth and intermediate in classes 1 (no basal resinosis but root[s] infected within 1 was greatly strengthened by including the period in which decline was m of root collar) and 2 (<, 50% basal resinosis). Differences among classes initiated in the regression equation. Additional keywords: root rot.