Patterns of initial versus delayed regeneration of white spruce in boreal mixedwood succession

2006 ◽  
Vol 36 (6) ◽  
pp. 1597-1609 ◽  
Author(s):  
Vernon S Peters ◽  
S Ellen Macdonald ◽  
Mark RT Dale
Keyword(s):  
Populus Tremuloides ◽  
Picea Glauca ◽  
Fire Severity ◽  
Mineral Soil ◽  
White Spruce ◽  
Mixedwood Forests ◽  
Regeneration Period ◽  
Postfire Regeneration ◽  
Distance To Seed Source ◽  
Mixedwood Stands

The timing of white spruce regeneration in aspen (Populus tremuloides Michx.) – white spruce (Picea glauca (Moench) Voss) boreal mixedwood stands is an important factor in stand development. We examined boreal mixedwood stands representing a 59-year period of time since fire and determined (1) whether and when a delayed regeneration period of white spruce occurred, (2) whether the relative abundance of initial (<20 years) versus delayed (≥20 years postfire) regeneration is related to seed availability at the time of the fire, and (3) what are the important regeneration substrates for initial versus delayed regeneration. Initial regeneration occurred primarily on mineral soil or humus, while delayed regeneration established primarily on logs and peaked 38–44 years after fire. Of the 20 stands investigated, seven were dominated by initial regeneration, six were dominated by delayed regeneration, and seven were even mixtures of both. The dominance of a site by initial or delayed regeneration could not be simply explained by burn timing relative to mast years or distance to seed source; our results suggested that fire severity and the competitive influence of initial regeneration on delayed regeneration were important at fine scales. Based on our results we describe several possible postfire successional pathways for boreal mixedwood forests.

Are mixtures of aspen and white spruce more productive than single species stands?

1999 ◽  
Vol 75 (3) ◽  
pp. 505-513 ◽  
Author(s):  
Rongzhou Man ◽  
Victor J. Lieffers
Keyword(s):  
Populus Tremuloides ◽  
Picea Glauca ◽  
White Spruce ◽  
Single Species ◽  
Physical Separation ◽  
Soil Resource ◽  
Mixedwood Forests ◽  
Environmental Extremes ◽  
Spruce Stands ◽  
Boreal Mixedwoods

In boreal mixedwood forests, aspen (Populus tremuloides) and white spruce (Picea glauca) commonly grow in mixture. These species may avoid competition through differential shade tolerance, physical separation of canopies, phenological differences, successional separation, and differences in soil resource utilization. Aspen may also be able to positively affect the growth of white spruce by improving litter decomposition and nutrient cycling rates, controlling grass and shrub competition, ameliorating environmental extremes, and reducing pest attack. These positive relationships likely make mixed-species stands more productive than pure stands of the same species. The evidence regarding the productivity of pure versus mixed aspen/white spruce stands in natural unmanaged forests is examined in this paper. Key words: Tree mixture; productivity; boreal mixedwoods; aspen; white spruce

scholarly journals Regeneration of aspen following partial and strip understory protection harvest in boreal mixedwood forests

2009 ◽  
Vol 85 (4) ◽  
pp. 631-638 ◽  
Author(s):  
Alison D Lennie ◽  
Simon M Landhäusser ◽  
Victor J Lieffers ◽  
Derek Sidders
Keyword(s):  
Forest Management ◽  
Key Words ◽  
Populus Tremuloides ◽  
Picea Glauca ◽  
Basal Area ◽  
White Spruce ◽  
Mixedwood Forests ◽  
Partial Harvest ◽  
Second Year

Trembling aspen regeneration was studied in 2 types of partial harvest systems designed to harvest mature aspen but protect immature spruce and encourage natural aspen regeneration. Two partial harvest systems, where the residual aspen was either left in strips or was dispersed uniformly, were compared to traditional clearcuts. After the first and second year since harvest, aspen sucker density and growth was similar between the 2 partial harvests, but was much lower than in the clearcuts. However, in the partial cuts the regeneration density was very much dependent on the location relative to residual trees. The density of regeneration was inversely related to the basal area of residual aspen; however, sucker height was inversely related to the basal area of the residual spruce. Although there were adequate numbers of suckers after partial harvest, their viability and contribution to the long-term productivity of these mixedwood stands is not clear. Key words: silvicultural systems, forest management, residual canopy, white spruce, Populus tremuloides, Picea glauca, traffic

Are mineral soils exposed by severe wildfire better seedbeds for conifer regeneration?

2006 ◽  
Vol 36 (8) ◽  
pp. 1943-1950 ◽  
Author(s):  
Kevin J Kemball ◽  
G. Geoff Wang ◽  
A Richard Westwood
Keyword(s):  
Populus Tremuloides ◽  
Picea Glauca ◽  
Pinus Banksiana ◽  
Seedling Recruitment ◽  
Black Spruce ◽  
Mineral Soil ◽  
White Spruce ◽  
Jack Pine ◽  
Conifer Regeneration ◽  
Mineral Soils

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.

White spruce (Picea glauca) restoration in temperate mixedwood stands using patch cuts and enrichment planting

2013 ◽  
Vol 89 (03) ◽  
pp. 392-400 ◽  
Author(s):  
François Hébert ◽  
Vincent Roy ◽  
Isabelle Auger ◽  
Martin-Michel Gauthier
Keyword(s):  
Picea Glauca ◽  
Seedling Survival ◽  
Ground Level ◽  
White Spruce ◽  
Forest Edge ◽  
Eastern Canada ◽  
Mixedwood Forests ◽  
Canopy Opening ◽  
Enrichment Planting ◽  
Mixedwood Stands

The use of gap-based silviculture and enrichment planting was tested in temperate mixedwood forests in eastern Canada. Four different sizes of canopy opening or patch cuts were applied to six stands in the maple–birch domain of Quebec. We evaluated the influence of opening size, cardinal quadrant within the opening, and distance from the forest edge of openings on white spruce height and ground-level diameter (GLD) five years after enrichment planting. At ≥5 m from the edge, initial canopy transmittance was generally >60% in all four canopy treatments. White spruce seedling height and GLD were lower within 10 m from the edge, and generally increased where understory light levels were higher. Seedling survival, height, and GLD in the smallest opening (0.05 ha) were comparable or higher than those found in relatively larger openings. The 0.05-ha opening that more closely emulates natural canopy gaps of temperate mixedwood forests provided satisfactory seedling development, and is therefore compatible with a gap-based stand dynamics approach to management of mixedwood stands in Quebec.

scholarly journals Semi-natural and intensive silvicultural systems for the boreal mixedwood forest

1996 ◽  
Vol 72 (3) ◽  
pp. 286-292 ◽  
Author(s):  
V. J. Lieffers ◽  
J. D. Stewart ◽  
R. B. Macmillan ◽  
D. Macpherson ◽  
K. Branter
Keyword(s):  
Populus Tremuloides ◽  
Land Tenure ◽  
Picea Glauca ◽  
Abies Balsamea ◽  
White Spruce ◽  
Growth And Yield ◽  
Mixedwood Forests ◽  
Seed Sources ◽  
Starting Point ◽  
Western Boreal Forest

Boreal mixedwood forests of aspen (Populus tremuloides) and white spruce (Picea glauca) are found on mesic sites in the western boreal forest. In the natural development of mixedwood stands, aspen is usually the first species to dominate the site. However, depending upon spruce seed sources and seedbeds, spruce can establish immediately after disturbance or in the next several decades. In most cases, spruce grow in the understory of deciduous species during its early development. If there are no spruce seed sources, aspen may be the sole tree species for a long period. In most circumstances, however, the longer-lived and taller white spruce eventually becomes the dominant species. If stands remain undisturbed for long periods, they will likely become uneven-aged mixtures of spruce and balsam fir (Abies balsamea). We propose silvicultural systems that will develop stands of a range of compositions, structures and value. As a starting point, we identify eight different mixed-wood compositions that might be identified in stand inventories, and propose various silvicultural treatments, including underplanting of white spruce, understory protection, shelterwood, and uneven-aged management. Fundamental changes in land tenure and silvicultural regulations, and improvements in estimation of growth and yield will be required before this range of management of mixed-woods can be implemented. Key words: aspen, white spruce, shelterwood, Populus tremuloides, Picea glauca, succession, ecosystem management

Seedbed variation from the interior through the edge of a large wildfire in Alberta

2005 ◽  
Vol 35 (7) ◽  
pp. 1640-1647 ◽  
Author(s):  
David F Greene ◽  
S Ellen Macdonald ◽  
Steve Cumming ◽  
Lynn Swift
Keyword(s):  
Populus Tremuloides ◽  
Life Histories ◽  
Fire Severity ◽  
Mineral Soil ◽  
Basal Area ◽  
White Spruce ◽  
Forest Composition ◽  
Fire Intensity ◽  
Soil Exposure ◽  
In Fire

Despite the importance of seedbeds in the life histories of many plant species, there has been little study of the seedbeds created by wildfire in fire-prone vegetation types such as the boreal forest. Both within the interior and at the edge of a very large (>100 000 ha) 2001 wildfire in the mixedwood boreal region of Alberta, we examined the postfire duff depth and the percent coverage of seedbed types. Minimizing the effect of site and forest composition, we looked only at Picea glauca (Moench) Voss – Populus tremuloides Michx. sites burned during a single day of high fire intensity. Good seedbeds (thin humus and exposed mineral soil, with or without ash) averaged 35% coverage within the interior of the fire but varied enormously among stands. There was a weak but significant positive correlation between prefire percent white spruce basal area and percent mineral soil exposure; that is, there is some tendency for conifer stands to create the seedbeds best suited for their own germinants. Fire severity played a clear role in mineral soil exposure, which was greatest in areas with 100% canopy mortality. Mineral soil exposure was far less at the edges of the fire, averaging only 5% even in areas where all trees had been killed; the burn edge was characterized by superficial flaming combustion with no evidence of substantial duff removal via smoldering combustion. In short, the areas where white spruce seed will be most common after the fire, the edges, are where the worst seedbeds in the burn will be found. Regeneration microsites at fire edges appear to be better suited to regeneration of broadleaf species, via suckering; the persistence of white spruce in fire-prone landscapes continues to be difficult to explain.

Impacts of drought on forest growth and regeneration following fire in southwestern Yukon, Canada

2005 ◽  
Vol 35 (9) ◽  
pp. 2141-2150 ◽  
Author(s):  
EH (Ted) Hogg ◽  
Ross W Wein
Keyword(s):  
Populus Tremuloides ◽  
Picea Glauca ◽  
White Spruce ◽  
Forest Growth ◽  
Burned Areas ◽  
Mixedwood Forests ◽  
Ring Analysis ◽  
Mature Stands ◽  
Similar Growth ◽  
Continental Climate

The valleys of southwestern Yukon have a continental climate with average annual precipitation of <300 mm. In 1958, fires burned large areas of mature mixedwood forests dominated by white spruce (Picea glauca (Moench) Voss) in the valleys near Whitehorse. Since then, the burned areas have shown poor regeneration of spruce, but have been colonized by scattered clones of trembling aspen (Populus tremuloides Michx.) interspersed by grassland. The objective of the study was to examine the influence of climatic variation on forest growth and regeneration in the 1958 burn and the adjacent unburned forests. Tree-ring analysis was conducted on 50 aspen and 54 white spruce in 12 mature stands where these species were codominant, and on 147 regenerating aspen in the 1958 Takhini burn. The mature stands were uneven-aged and the patterns of growth variation for the aspen and spruce between 1944 and 2000 were similar. Growth of both species was most strongly related to variation in precipitation. The regenerating aspen had a wide age-class distribution (1959–2000) and their growth was also positively related to precipitation. The results indicate that these forests have been slow to regenerate after fire, and are vulnerable if the climate becomes drier under future global change.

scholarly journals Effects of substrate availability and competing vegetation on natural regeneration of white spruce on logged boreal mixedwood sites

2018 ◽  
Vol 48 (4) ◽  
pp. 324-332 ◽  
Author(s):  
Nicola A. Kokkonen ◽  
S. Ellen Macdonald ◽  
Ian Curran ◽  
Simon M. Landhäusser ◽  
Victor J. Lieffers
Keyword(s):  
Picea Glauca ◽  
Natural Regeneration ◽  
Negative Impact ◽  
Mineral Soil ◽  
Soil Surface ◽  
White Spruce ◽  
Solid Wood ◽  
Seedling Mortality ◽  
Competing Vegetation ◽  
Survival And Growth

Given a seed source, the quality of available substrates is a key factor in determining the success of white spruce (Picea glauca (Moench) Voss) natural regeneration. We examined the influence of substrate and competing vegetation on survival and growth of natural regeneration of white spruce up to 4 years following harvesting in deciduous-dominated upland boreal mixedwood sites. Feather moss, thick soil surface organic layers, litter, and solid wood were poor substrates for establishment. Early successional mosses establishing on mineral soil, thin organics, and rotten wood were generally favourable microsites but were not highly available on postharvest sites. Mineral soil substrates were not as suitable as expected, likely because on a postlogged site, they are associated with unfavourable environmental characteristics (e.g., low nutrient availability, exposure). There was some evidence that survival and growth of seedlings were improved by surrounding vegetation in the first years, but heavy competing vegetation had a negative impact on older seedlings. Burial by aspen litter greatly increased seedling mortality, especially when combined with a brief period of submergence due to heavy spring snowmelt. The results provide insight into conditions under which natural regeneration could be an option for establishing white spruce following harvesting of deciduous-dominated boreal mixedwood forests.

scholarly journals Taper Equations for Five Major Commercial Tree Species in Manitoba, Canada

2007 ◽  
Vol 22 (3) ◽  
pp. 163-170 ◽  
Author(s):  
Ryan J. Klos ◽  
G. Geoff Wang ◽  
Qing-Lai Dang ◽  
Ed W. East
Keyword(s):  
Populus Tremuloides ◽  
Picea Glauca ◽  
Pinus Banksiana ◽  
White Spruce ◽  
Jack Pine ◽  
Volume Estimation ◽  
Trembling Aspen ◽  
Stem Form ◽  
Taper Equation ◽  
Taper Equations

Abstract Kozak's variable exponent taper equation was fitted for balsam poplar (Populus balsamifera L.), trembling aspen (Populus tremuloides Michx.), white spruce (Picea glauca [Moench] Voss), black spruce (Picea mariana [Mill.] B.S.P.), and jack pine (Pinus banksiana Lamb.) in Manitoba. Stem taper variability between two ecozones (i.e., Boreal Shield and Boreal Plains) were tested using the F-test. Regional differences were observed for trembling aspen, white spruce, and jack pine, and for those species, separate ecozone-specific taper equations were developed. However, the gross total volume estimates using the ecozone-specific equations were different from those of the provincial equations by only 2 percent. Although the regional difference in stem form was marginal within a province, a difference of approximately 7 percent of gross total volume estimation was found when our provincial taper equations were compared with those developed in Alberta and Saskatchewan. These results suggest that stem form variation increases with spatial scale and that a single taper equation for each species may be sufficient for each province.

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