Growth and dieback of aspen forests in northwestern Alberta, Canada, in relation to climate and insects

2002 ◽  
Vol 32 (5) ◽  
pp. 823-832 ◽  
Author(s):  
E H Hogg ◽  
James P Brandt ◽  
B Kochtubajda
Keyword(s):  
Boreal Forest ◽  
Populus Tremuloides ◽  
Fungal Pathogens ◽  
Forest Health ◽  
Deciduous Tree ◽  
Late Winter ◽  
Future Health ◽  
Secondary Damage ◽  
The 1960S ◽  
Canadian Boreal Forest

Trembling aspen (Populus tremuloides Michx.) is the most important deciduous tree in the Canadian boreal forest, with >1000 Tg of carbon stored in the aboveground biomass of this species. Since the early 1990s, aspen dieback has been noted over parts of the southern boreal forest and aspen parkland in western Canada. In this study, tree-ring analysis and forest health assessments were conducted in 18 aspen stands near Grande Prairie, Alta., to examine causes of reduced growth and dieback. Defoliation histories were reconstructed based on light-colored ("white") tree rings and records of past insect outbreaks. The results indicated that several factors contributed to the observed dieback. Defoliation by forest tent caterpillar (Malacosoma disstria Hbn.) and drought in the 1960s and 1980s led to reduced growth and predisposed some stands to secondary damage by wood-boring insects and fungal pathogens. Thaw–freeze events during a period (1984–1993) of unusually light snow cover in late winter may have also contributed to the observed dieback. Under global change, the severity of these stressors may increase, which would pose a serious concern for the future health, productivity, and carbon sequestration of aspen forests in the region.

Factors affecting interannual variation in growth of western Canadian aspen forests during 1951-2000

2005 ◽  
Vol 35 (3) ◽  
pp. 610-622 ◽  
Author(s):  
EH (Ted) Hogg ◽  
James P Brandt ◽  
B Kochtubajda
Keyword(s):  
Populus Tremuloides ◽  
Interannual Variation ◽  
Regional Scale ◽  
Forest Health ◽  
Basal Area ◽  
Deciduous Tree ◽  
Severe Drought ◽  
Moisture Index ◽  
Canadian Prairies ◽  
The North

Trembling aspen (Populus tremuloides Michx.) is the most important deciduous tree in the North American boreal forest and is also the dominant tree in the aspen parkland zone along the northern edge of the Canadian prairies. Since the 1990s, observations of dieback and reduced growth of aspen forests have led to concerns about the potential impacts of climate change. To address these concerns, a regional-scale study (CIPHA) was established in 2000 that includes annual monitoring of forest health and productivity of 72 aspen stands across the western Canadian interior. Tree-ring analysis was conducted to determine the magnitude and cause of temporal variation in stand growth of aspen at the scale (1800 km × 500 km area) encompassed by this study. The results showed that during 1951–2000 the region's aspen forests underwent several cycles of reduced growth, notably between 1976 and 1981, when mean stand basal area increment decreased by about 50%. Most of the growth variation was explained by interannual variation in a climate moisture index in combination with insect defoliation. The results of the analysis indicate that a major collapse in aspen productivity likely occurred during the severe drought that affected much of the region during 2001–2003.

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.

Fungi and diseases — natural components of healthy forestsThis article is one of a collection of papers based on a presentation from the Stem and Shoot Fungal Pathogens and Parasitic Plants: the Values of Biological Diversity session of the XXII International Union of Forestry Research Organization World Congress meeting held in Brisbane, Queensland, Australia, in 2005.

Botany ◽  
2009 ◽  
Vol 87 (1) ◽  
pp. 22-25 ◽  
Author(s):  
M. E. Ostry ◽  
G. Laflamme
Keyword(s):  
Fungal Pathogens ◽  
Biological Diversity ◽  
Forest Health ◽  
Disease Outbreaks ◽  
Ecological Interactions ◽  
Negative Effects ◽  
Land Owners ◽  
Negative Impacts ◽  
The Many ◽  
Native Fungi

Forest health is described and perceived in different ways by the general public, land owners, managers, politicians, and scientists, depending on their values and objectives. Native tree pathogens and diseases are often associated with negative impacts even though damage is limited or not widespread. Too often, the concepts of tree health and forest health are used interchangeably and are not related to scale. Similar to fire, occurrences of disease outbreaks focus on the negative effects. However, native pathogens often exist in equilibrium with natural forest communities so their critical ecological roles are not easily discernible. Examined holistically, native fungi and diseases, dead and dying trees, and the many complex ecological interactions among them provide valuable benefits that ultimately contribute to sustainable, healthy forest ecosystems.

Effects of open-range cattle grazing on deciduous tree regeneration, damage, and mortality following patch logging

2014 ◽  
Vol 44 (7) ◽  
pp. 777-783 ◽  
Author(s):  
Jillian Kaufmann ◽  
Edward W. Bork ◽  
Michael J. Alexander ◽  
Peter V. Blenis
Keyword(s):  
Populus Tremuloides ◽  
Sustainable Forest Management ◽  
Deciduous Forest ◽  
Total Mortality ◽  
Cattle Grazing ◽  
Tree Regeneration ◽  
Deciduous Tree ◽  
Populus Balsamifera ◽  
Haul Road ◽  
The Impact

The impact of summer cattle grazing on deciduous tree regeneration within uncut forests, clearcuts, partially harvested areas, and in-block haul road habitats was examined in four experimental pastures of central Alberta during 2008 and 2009. Sampling of 233 field plots, both inside and outside cattle exclosures, was used to document sapling densities, height, and type of damage. Tree densities (primarily aspen (Populus tremuloides Michx.)) differed among habitats but less so with exposure to cattle. Densities were greatest in clearcuts, followed by partially harvested areas and then uncut forest and haul roads. While exposure to cattle reduced total tree regeneration, sapling densities and sizes remained sufficient to meet postharvest standards for deciduous forest regeneration in Alberta, even with exposure to cattle. Cattle damage in harvested areas was primarily from browsing (≤3.2% of saplings), with proportionally more trees affected in uncut forests (8.6%). Browsing was particularly high on balsam poplar (Populus balsamifera L.) (25%) during 2008. Although sapling damage increased with high cattle stocking in 2008 (to 10.5%), total mortality was limited to 15.5% through 2009. These findings show that despite cattle impacts to some saplings, damage levels were insufficient to alter deciduous regeneration, highlighting the compatibility of cattle grazing and sustainable forest management on public lands in this region.

Fungi of the Canadian boreal forest region: Catulus aquilonius gen. et sp.nov., a hyperparasite on Seuratia millardetii

1978 ◽  
Vol 56 (19) ◽  
pp. 2344-2347 ◽  
Author(s):  
D. Malloch ◽  
C. T. Rogerson
Keyword(s):  
Boreal Forest ◽  
New Genus ◽  
New Genus And Species ◽  
Forest Region ◽  
Canadian Boreal Forest ◽  
Boreal Forest Region

A new genus and species of ascomycetes, Catulus aquilonius, is described, illustrated, and tentatively assigned to the Mycosphaerellaceae. It grows as a parasite on stromata of Seuratia millardetii (Raciborski) Meeker and is characterized by two-celled, setulose ascospores.

scholarly journals Large-area mapping of Canadian boreal forest cover, height, biomass and other structural attributes using Landsat composites and lidar plots

2018 ◽  
Vol 209 ◽  
pp. 90-106 ◽  
Author(s):  
Giona Matasci ◽  
Txomin Hermosilla ◽  
Michael A. Wulder ◽  
Joanne C. White ◽  
Nicholas C. Coops ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Forest Cover ◽  
Large Area ◽  
Canadian Boreal Forest

Integrating accessibility and intactness into large-area conservation planning in the Canadian boreal forest

2013 ◽  
Vol 167 ◽  
pp. 371-379 ◽  
Author(s):  
Ryan P. Powers ◽  
Nicholas C. Coops ◽  
Trisalyn Nelson ◽  
Michael A. Wulder ◽  
C. Ronnie Drever
Keyword(s):  
Boreal Forest ◽  
Conservation Planning ◽  
Large Area ◽  
Canadian Boreal Forest

scholarly journals Fire deficit increases wildfire risk for many communities in the Canadian boreal forest

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Marc-André Parisien ◽  
Quinn E. Barber ◽  
Kelvin G. Hirsch ◽  
Christopher A. Stockdale ◽  
Sandy Erni ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Wildfire Risk ◽  
Canadian Boreal Forest
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