Ecological studies in the boreal spruce–fir forests of the North American taiga. II. Analysis of the bryophyte flora

1976 ◽  
Vol 54 (7) ◽  
pp. 619-643 ◽  
Author(s):  
George H. La Roi ◽  
Muriel H. L. Stringer

The bryoflora of 34 white spruce – fir and 26 black spruce stands in the boreal forest subzone consisted of 100 mosses and 33 liverworts. Short turfs, smooth mats, threaded mats, and tall erect turfs were the most species-rich growth-forms; wefts were cover dominants. White spruce – fir stands had more species but lower cover than black spruce. The liverwort:moss species ratio in white spruce – fir increased with precipitation. Based on bryoflora and geography, stands were classified as follows: white spruce – fir, Hylocomium splendens – Pleurozium schreberi order (= three associations of western Ceratodon purpureus – Pylaisiella polyantha alliance and two associations of eastern Rhynchostegium serrulatum – Tetraphis pellucida alliance); black spruce, Pleurozium schreberi – Hylocomium splendens order (= three associations of western Drepanocladus uncinatus – Brachythecium salebrosum alliance and two associations of eastern Sphagnum – Hypnum pallescens alliance). Of the 32 most important species, 16 'preferred' wood, 7 needle litter, 6 mineral soil, and 3 bark. The ground cover hierarchy in white spruce – fir was weft mosses > detritus [Formula: see text] needles > wood > other bryophytes > lichens > bark > soil; in black spruce, wood and other bryophytes were reversed. Higher species richness of white spruce – fir stands was ascribed to higher productivity and greater age, which gives a greater diversity and quantity of woody substrates for microsuccessional species. Shortage of suitable substrate and competition from weft mosses may explain the consistently low abundance of most other bryophytes in the two community types.

2007 ◽  
Vol 37 (1) ◽  
pp. 62-73 ◽  
Author(s):  
Martin Lavoie ◽  
David Paré ◽  
Yves Bergeron

The surface of the soil in recently harvested or burned lowland black spruce (Picea mariana (Mill.) BSP) sites is composed of a fine mosaic of different bryophytes (mostly Sphagnum spp. and feathermosses), disturbed organic material originating mostly from mosses at different stages of decay, and exposed mineral soil. Growth substrates were compared in lowland black spruce stands regenerating after either careful logging or wildfire. The 3-year annual increment for black spruce seedlings was greatest with substrates of feathermosses, mainly Pleurozium schreberi (Brid.) Mitt., fibric material of P. schreberi origin, and a mixture of fibric P. schreberi and humic materials; it was least with fibric Sphagnum spp., mineral soil, and decaying wood substrates. The most favourable substrates for growth were characterized by better black spruce N and P foliar status. Our results also suggest that categories of growth substrates in the rooting zone reflect nutritional quality better than categories of growth substrates on the soil surface. To maintain or increase black spruce growth following careful logging of sites prone to paludification, we recommend fill-planting of seedlings in substrates originating from P. schreberi; management techniques that favour P. schreberi over Sphagnum mosses should also be developed.


1988 ◽  
Vol 64 (1) ◽  
pp. 70-75 ◽  
Author(s):  
Richard A. Sims ◽  
William D. Towill

Shallow-soil sites in the Nipigon-Beardmore area of northern Ontario are widespread and pose unique operational problems for forest managers. Several working definitions of shallow soils are used in Ontario. More accurate regional definitions are required in order that silvicultural decisions for these sometimes fragile sites may be refined or new ones developed. Harvesting and silvicultural options for shallow-soil sites are limited in the North Central Region.A program of Forest Ecosystem Classification (FEC) for the North Central Region has been designed to provide better understanding of shallow sites and a framework of standardized definitions. The FEC describes several shallow-soil types that occur over boulder pavement or bedrock, and differentiates mainly on the basis of depth-to-rock contact, surface organic material thickness and texture of the primary mineral soil particles. Operational application of this classification may require identification of complexes of shallow-soil types.


1989 ◽  
Vol 19 (11) ◽  
pp. 1389-1396 ◽  
Author(s):  
C. T. Dyrness ◽  
K. Van Cleve ◽  
J. D. Levison

Soil chemical properties were studied after a wildfire in stands of white spruce (Piceaglauca (Moench) Voss), black spruce (Piceamariana (Mill.) B.S.P.), paper birch (Betulapapyrifera Marsh.), and quaking aspen (Populustremuloides Michx.). Samples of the forest floor and surface 5 cm of mineral soil were collected from burned sites and unburned controls and analyzed soon after the fire. With the exception of soil pH, effects of the fire on soil chemistry differed among the four forest types. Generally, amounts of exchangeable K, Ca, and Mg did not appreciably increase in the forest floor and surface mineral soil except in heavily burned areas in white spruce and black spruce. Fire reduced amounts of N by about 50% in white spruce, aspen, and birch forest floors. In black spruce, quantities of N were slightly higher in heavily burned locations. Forest floor C:N ratios were substantially lower in heavily burned locations in white spruce and black spruce than in unburned controls. Burning did not have a marked influence on supplies of available P in the forest floor, except in heavily burned black spruce, where average amounts were 12.50 g/m2 versus only 0.46 g/m2 in the control. Burning caused more moderate gains in available P in surface mineral soils under aspen and white spruce. We concluded that fire caused marked short-term changes in soil chemistry in the four forest types. How long these changes will persist is unknown.


1968 ◽  
Vol 44 (2) ◽  
pp. 25-28 ◽  
Author(s):  
W. Stanek

Black spruces of layer or seed origin develop into merchantable trees with similar growth in height, diameter and volume. Layerings tend to have a poorer stem form than seedlings, especially under adverse growing conditions. However, stem form of old layering trees is considerably better. The proportion of layerings and seedlings is influenced by stand history. Black spruce stands undisturbed for a long time consist largely of layerings. After fire, scarification, or exposure of mineral soil, stands regenerate mainly from seedlings. Stocking of black spruce is satisfactory where advance growth has been preserved after cutting, whether it is of layer or of seed origin.


1996 ◽  
Vol 74 (12) ◽  
pp. 1937-1942 ◽  
Author(s):  
Katherine A. Frego

The feather moss community in upland black spruce stands is dominated by Pleurozium schreberi, with small pure colonies and mixtures of ubiquitous and apparently persistent minor species. Previous studies indicated that this spatial pattern is not due to microsite conditions. This study tested the hypothesis that the minor species persist by dynamic occupation of small disturbance-type gaps. Colonization of experimental gaps (10 cm diameter, three substrate types) was tracked over 2 years to determine (i) how Pleurozium and the three minor species colonize gaps and (ii) how characteristics of the gaps affect colonization. All species colonized by encroachment of surrounding vegetative shoots. Availability of propagules, i.e., species composition of the surrounding bed, had the greatest impact, but regeneration of two species was affected by substrate: Ptilium growth was reduced on spruce needles, whereas that of Ptilidium was increased. Pleurozium schreberi displayed the most rapid growth in terms of shoot encroachment regardless of gap characteristics. By virtue of its abundant propagules and rapid growth, Pleurozium is most likely to colonize randomly located disturbance-type gaps, hence maintaining its dominance. Differentiation in regeneration characteristics does not account for the persistence of the minor species in the community. Keywords: Pleurozium schreberi, Ptilium crista-castrensis, Dicranum polysetum, Ptilidium ciliare, gap dynamics, community structure.


2006 ◽  
Vol 86 (1) ◽  
pp. 1-9 ◽  
Author(s):  
N. Fenton ◽  
S. Légaré ◽  
Y. Bergeron ◽  
D. Paré

Globally, soil anoxia and water table rise play a role in the development of peatlands from forests. Cited causes have included a diversity of internal and external mechanisms, including Sphagnum and feather mosses, hardpan development, and peatland expansion. The objectives of this study were to examine water table depth in black spruce stands of the Clay Belt of Quebec and Ontario, and to associate changes with potential stand scale causal factors (primarily biological). A methodological issue, the link between oxygen zone and water table, was also addressed. Within stands less than 100 yr post-fire, oxygen zone and water table position were only loosely related, and no other potential factors were significantly correlated. Across a chronosequence of stands, while oxygen zone thickness in the soil profile was relatively constant, its position relative to the mineral soil changed, as it rose from the mineral soil into the forest floor. Forest floor thickness was the dominant explanatory factor in oxygen zone position, suggesting that in these forests other postulated mechanisms are less important. At the landscape level, the movement of the oxygen zone into the forest floor has important consequences for the long-term productivity of this intensively exploited forest region. Key words: Water table, black spruce, paludification, forest floor, Clay Belt, Sphagnum


2001 ◽  
Vol 79 (4) ◽  
pp. 420-428 ◽  
Author(s):  
Jean-François Giroux ◽  
Yves Bergeron ◽  
Jean J Veillette

Giant circular patterns of low tree density in black spruce (Picea mariana) stands were investigated in the Abitibi region of Quebec. We used dendrochronological techniques to test the hypotheses that ring patterns of low tree density are caused either by radial changes in spruce mortality or productivity. Seven circles were sampled. We found no gradient in the age of spruce along circle radii suggesting that rings of low tree density do not expand radially, that is, they are not spatially dynamic entities. The results indicate, however, that spruce trees were less dense and productive within the rings due to excessive moisture in the soil. Measurements of surface elevation, thickness of the organic layer and elevation of the mineral substrate across the circles revealed that a depression in the mineral soil beneath the rings traps the surface water and this area of poor drainage seems to prevent the establishment of black spruce within the rings. The origin of the ring-shaped depressions was attributed to geological or geomorphological causes.Key words: black spruce, Picea mariana, mortality, productivity, rings, geomorphology.


2006 ◽  
Vol 36 (8) ◽  
pp. 1943-1950 ◽  
Author(s):  
Kevin J Kemball ◽  
G. Geoff Wang ◽  
A Richard Westwood

We examined jack pine (Pinus banksiana Lamb.), black spruce (Picea mariana (Mill.) BSP), and white spruce (Picea glauca (Moench) Voss) seed germination and seedling recruitment in aspen (Populus tremuloides Michx.) and conifer mixedwood stands following the 1999 Black River fire in southeastern Manitoba, Canada. Three postfire seedbed types were tested: scorched (surface litter only partially consumed), lightly burned (surface litter consumed with little or no duff consumption), and severely burned (complete consumption of litter and duff exposing mineral soil). Seeds were sown in 1999, 2000, and 2001, and each cohort was monitored for 3 years. In 1999, severely burned seedbeds had poor germination, while scorched seedbeds had the highest germination. The reverse was true in 2001. After the first growing season, continued survival of seedlings was greater on severely burned seedbeds for all three cohorts. However, better survival on severely burned seedbeds was not sufficient to overcome poor germination in 1999 and 2000. When using artificial seeding to promote conifer regeneration, we recommend a delay of one full year after a severe spring fire for jack pine and two full years for black spruce and white spruce on boreal aspen and conifer mixedwood sites.


2003 ◽  
Vol 33 (10) ◽  
pp. 1874-1879 ◽  
Author(s):  
Nicolas Bélanger ◽  
David Paré ◽  
Stephen H Yamasaki

The effect of different harvesting practices on soil acid–base status was evaluated in black spruce (Picea mariana (Mill.) BSP) forests of Quebec by comparing soil from five pairs of whole-tree and stem-only harvested plots 3 years after harvest. Stem-only harvesting contributed to the enrichment of the exchangeable base cation pool, particularly in the forest floors of the pairs where whole-tree harvested plots showed the highest exchangeable Al3+. In the mineral soil, divergence between treatments was low, perhaps because these acidic soils were strongly saturated with Al3+ (about 90%), which did not favour cationic exchange reactions. Although the effects of treatment may not persist over time, improved base cation nutrition may benefit stands during the early stages of development. Over a forest rotation of about 85 years, the estimated loss of alkalinity due to whole-tree harvesting was estimated to be low (less than 20%) when compared with the effect of acidic deposition.


1973 ◽  
Vol 105 (1) ◽  
pp. 113-122 ◽  
Author(s):  
A. F. Hedlin

AbstractInsects cause considerable loss of seed in white spruce, Picea glauca (Moench) Voss, and Engelmann spruce, P. engelmannii Parry, in British Columbia. The most important species are a maggot, Hylemya anthracina (Cz.), and a seed moth, Laspeyresia youngana (Kit.). Other insects are: a seed chalcid, Megastigmus piceae Roh., a cone axis midge, Dasineura rachiphaga Tripp, a gall midge, D. canadensis Felt, a seed midge, Mayetiola carpophaga Tripp, and a scale-feeding midge. These insects also occur in cones of Sitka spruce, P. sitchensis (Bong.) Carr., and black spruce, P. mariana (Mill.) BSP.The systemic insecticides dimethoate and formothion proved to be effective against these insects when applied as sprays following pollination in mid-June.


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