The response of the feather moss, Pleurozium schreberi, to 5 years of simulated acid precipitation in the Canadian boreal forest

1988 ◽  
Vol 66 (1) ◽  
pp. 82-88 ◽  
Author(s):  
Thomas C. Hutchinson ◽  
Martha G. Scott
Keyword(s):  
Boreal Forest ◽  
Dry Weight ◽  
Acid Precipitation ◽  
Permanent Plots ◽  
Pleurozium Schreberi ◽  
Forest Site ◽  
Percent Cover ◽  
Feather Moss ◽  
Lateral Branches ◽  
Canadian Boreal Forest

Permanent plots dominated by the feather moss, Pleurozium schreberi (Brid.) Mitt., were established at a Canadian boreal forest site to study the effects of simulated acid precipitation on percent cover, growth, and photosynthesis of vegetation. For a 5-year period, beginning in 1981, plots of P. schreberi received twice-monthly sprayings of simulated rain, adjusted to pH 5.6, 4.0, 3.5, 3.0, or 2.5 with a 2:1 molar mixture of sulfuric and nitric acids. Unsprayed plots were also monitored. Almost complete elimination of the moss had occurred in the plots sprayed with pH 2.5 by the end of the 2nd year of treatment, and substantial decreases in cover were also recorded at pH 3.0 and 3.5 over the 5 years. Significant reductions of up to 75% in total and living frond height and dry weight were recorded at pH 3.5 and lower. Lateral branches produced in acid-treated plots also were stunted and few in number. This decline in growth and percent cover of P. schreberi may have resulted from the decreased net photosynthetic rates measured in the field and would be accelerated by increased rates of evapotranspiration in the altered moss microhabitat.

Contrasting responses of lichens and Vaccinium angustifolium to long-term acidification of a boreal forest ecosystem

1989 ◽  
Vol 67 (2) ◽  
pp. 579-588 ◽  
Author(s):  
Martha G. Scott ◽  
Thomas C. Hutchinson ◽  
Marilyn J. Feth
Keyword(s):  
Boreal Forest ◽  
Growth Parameters ◽  
Light Attenuation ◽  
Net Photosynthesis ◽  
Dry Weight ◽  
Forest Understory ◽  
Permanent Plots ◽  
Percent Cover ◽  
Vaccinium Angustifolium ◽  
Understory Species

Over a 5-year period, we investigated the effects of simulated acidic precipitation on boreal forest understory species. Percent cover, net photosynthetic rate, and growth of three species of subarctic lichens were evaluated. Throughout the growing season, Cladina stellaris, Cladina rangiferina, and Cladina mitis, along with the associated vascular perennial, Vaccinium angustifolium, received twice-monthly sprays of artificial rain adjusted to pH 5.6, 4.0, 3.5, 3.0, or 2.5 using a 2:1 ratio of sulfuric to nitric acids. Changes in percent cover of the flora in permanent plots were measured annually during treatment years and then for a 6th year to monitor postspray recovery. Following 5 years of spraying, combined cover values for the three lichen species had decreased by up to 27% in plots sprayed with rain of less than pH 4.0, while percent cover of V. angustifolium had increased by 55 %. Although losses in net photosynthesis of 65% occurred for lichens receiving rains of pH 2.5, differences were not significant and data were highly variable. However, increasing acidity of the sprays significantly suppressed mean podetial height and dry weight of C. stellaris and C. mitis. The effect on these lichens of shading by the potential competitor V. angustifolium was investigated in a companion study, and it was concluded that the growth suppression of C. stellaris was most likely related to rainfall acidity and not to light attenuation. Cladina mitis was more sensitive to low light levels. Although adversely affected by rain of pH 2.5, C. rangiferina showed stimulation of a number of growth parameters in plots sprayed with rain of pH 3.0. It was concluded that responses of boreal understory species are variable and complex, and that several species (i.e., C. rangiferina and V. angustifolium) are tolerant of rainfall of less than pH 3.5.

Identification of two genera of N2-fixing cyanobacteria growing on three feather moss species in boreal forests of Quebec, Canada

2006 ◽  
Vol 84 (6) ◽  
pp. 1025-1029 ◽  
Author(s):  
Daniel Houle ◽  
Simon Bilodeau Gauthier ◽  
Serge Paquet ◽  
Dolors Planas ◽  
Annabelle Warren
Keyword(s):  
Boreal Forest ◽  
Boreal Forests ◽  
Pleurozium Schreberi ◽  
Large Area ◽  
Moss Species ◽  
Feather Moss ◽  
Canadian Boreal Forest ◽  
First Time

The recent discovery that N2 fixation rates by the feather moss carpet of boreal Scandinavian forests increases with stand maturity has put into question the paradigm that N2 fixation is negligible in mature boreal forest. The N2 fixation was attributed to a previously unknown association between Nostoc sp., a N2-fixing cyanobacteium and Pleurozium schreberi (Brid.) Mitt., a feather moss that is abundant worldwide in the boreal forest. Here we report for the first time that this association also exists in the Canadian boreal forest. We discovered, however, that Nostoc was found growing not only on Pleurozium but also on two other moss species ( Hylocomnium splendens (Hedw.) Br. Eur. and Ptillium crista-castrensis (Hedw.) De Not.). In addition, the N2-fixing cyanobacterium Stigonema sp. was observed on the three moss species mentioned above, indicating the existence of six different associations. At least one of the six associations was found at 9 of 13 sites that are representative of a large area of the Quebec boreal forest. These findings suggest possibilities for further research, aimed at measuring the unaccounted for N2-fixing potential of the feather moss carpet in Canadian boreal forests.

scholarly journals Abundance and Impacts of Competing Species on Conifer Regeneration Following Careful Logging in the Eastern Canadian Boreal Forest

Forests ◽  
2019 ◽  
Vol 10 (2) ◽  
pp. 177 ◽  
Author(s):  
Louis-Philippe Ménard ◽  
Jean-Claude Ruel ◽  
Nelson Thiffault
Keyword(s):  
Boreal Forest ◽  
Basal Area ◽  
Low Fertility ◽  
Percent Cover ◽  
Large Area ◽  
Competing Species ◽  
Competing Vegetation ◽  
Conifer Regeneration ◽  
Ericaceous Shrubs ◽  
Canadian Boreal Forest

Managing competing vegetation is crucial in stand establishment strategies; forecasting the abundance, composition, and impact of competing vegetation after harvesting is needed to optimize silviculture scenarios and maintain long-term site productivity. Our main objective was to identify factors influencing the short-term abundance and composition of competing vegetation over a large area of the Canadian boreal forest. Our second objective was to better understand the mid-term evolution of the regeneration/competing vegetation complex in cases of marginal regeneration conditions. We used operational regeneration surveys of 4471 transects sampled ≈5 years after harvesting that contained data on regeneration, competing vegetation, elevation, ecological classification, soil attributes, and pre-harvest forest stands. We performed a redundancy analysis to identify the relationships between competing vegetation, harvesting and biophysical variables. We then estimated the probability of observing a given competing species cover based on these variables. In 2015, we re-sampled a portion of the sites, where conifer regeneration was marginal early after harvesting, to assess the temporal impact of different competing levels and species groups on the free-to-grow stocking, vigour and basal area of softwood regeneration. Results from the first inventory showed that, after careful logging around advance growth, ericaceous shrubs and hardwoods were not associated with the same sets of site attributes. Ericaceous shrubs were mainly found on low fertility sites associated with black spruce (Picea mariana (Mill.) BSP) or jack pine (Pinus banksiana Lamb.). The distinction between suitable environments for commercial shade-intolerant hardwoods and non-commercial hardwoods was less clear, as they responded similarly to many variables. Analysis of data from the second inventory showed a significant improvement in conifer free-to-grow stocking when commercial shade-intolerant hardwood competing levels were low (stocking 0%–40%) and when ericaceous shrubs competing levels were moderate (percent cover 26%–75%). In these conditions of marginal regeneration, the different types and intensities of competition did not affect the vigour or basal area of softwood regeneration, 9–14 years after harvesting.

Morphometrics of the aerial roots of Kingia australis (Liliales)

1981 ◽  
Vol 29 (1) ◽  
pp. 81 ◽  
Author(s):  
B Lamont
Keyword(s):  
Fire History ◽  
Dead Zone ◽  
Dry Weight ◽  
Root Primordia ◽  
Stem Apex ◽  
Primary Roots ◽  
Aerial Roots ◽  
History Of ◽  
Lateral Branches ◽  
Potential Height

Kingia australis, common in the heaths and forests of south-western Australia, is distinguished from all other grass trees in Australia by the presence of a mantle of concealed aerial roots. A ring of up to 50 root primordia is initiated in winter from the stem apex. In plants more than 1 m high, initiation and commencement of elongation of the primary roots are no longer annual but dependent on the fire history of the plant. These roots descend between the stem and persistent leaf bases at about 2 cm per growing month, sending many lateral branches among the leaf bases. Aerial roots gradually replace the space occupied by the leaf bases until they may account for 45% of the dry weight of the aerial caudex. The caudex of one 6-m-high specimen bore up to 27 roots per cm2 transection of the root mantle, with about 3000 primary roots entering the soil. All underground primary roots (except the initial contractile roots) have an aerial origin and are concentrated vertically under the canopy. After 300-400 years the stem starts to die back from the base, and the aerial roots attached to that portion disintegrate. By propping up the stem and bridging the dead zone of the stem, the living aerial roots greatly extend the potential height and longevity of the plant. In addition, the hairy laterals are ideally located to absorb water and nutrients directly from the leaf bases. Protective and aerating functions are also indicated.

Two new species of Oidiodendron from boreal forest soils

1968 ◽  
Vol 46 (3) ◽  
pp. 203-206 ◽  
Author(s):  
R. A. A. Morrall
Keyword(s):  
New Species ◽  
Boreal Forest ◽  
Forest Soils ◽  
Nomen Dubium ◽  
Two New Species ◽  
Canadian Boreal Forest

Oidiodendron periconioides Morrall sp. nov. and O. chlamydosporicum Morrall sp. nov. are described from Canadian boreal forest soils. O. gracile Zhdanova is considered to be a nomen dubium.

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