Forest Of Alberta Research Articles

Change detection and landscape structure mapping using remote sensing

Satellite remote sensing has long held promise as a powerful method of detecting forest canopy changes and mapping landscape structure over vast, often multi-jurisdictional forest areas. Landsat Thematic Mapper (TM) spectral response, for example, can be related accurately to changes in physiology and cover at a range of small to intermediate mapping scales. These data have been available continuously for almost 20 years; many areas have earlier satellite image archives stretching back to the 1970s. When considering spatially-explicit changes to landscapes—caused by natural and human disturbances—over this time period, digital, synoptic, and repeatable satellite remotely-sensed data are emerging as the observational media of choice that forest managers must possess and use wisely. In this paper, successful use of satellite remote sensing in two of Canada’s Model Forests is described. First, in the Fundy Model Forest in southeastern New Brunswick, a 15-year TM image sequence was used to detect area changes associated with different harvesting and silvicultural practices. Second, in the Foothills Model Forest in west-central Alberta, grizzly bear habitat maps have been created from multi-scene TM land cover mosaics. These map products constitute critical information on landscape change and configuration required to answer key management questions. The paper concludes with a prognosis for the future role of satellite remote sensing in sustainable forest management as data quality continues to improve (i.e., increasing spatial, spectral, temporal, and radiometric resolutions), and methods are brought into the purview of forest managers and practitioners. Key words: remote sensing, landscape change, forest fragmentation, human disturbance, management information needs, habitat

Habitat associations of black-backed and three-toed woodpeckers in the boreal forest of Alberta

Recent studies suggest that black-backed (Picoides arcticus) and three-toed woodpeckers (Picoides tridactylus) might decrease in abundance because of habitat loss from fire suppression and short-rotation logging in landscapes managed for forestry. We examined black-backed and three-toed woodpecker occupancy of stands in a 2-year post-fire forest, mature and old-growth spruce and pine forests, and six post-fire coniferous forests of different ages. Three-toeds were detected in old stands and in the 2-year-old burn, and their probability of occupancy of burned forests decreased between 3 and 8 years post-fire. Within 50 km of the 2-year-old burn, black-backs were only detected in the burn and not in old-growth or mature conifer stands. However, they did occupy old coniferous stands located 75 and 150 km from the recent burn. They had a similar probability of occupying stands in the 3-, 4-, and 8-year-old burns but were not detected in the 16-year-old burn. The persistence of three-toed woodpeckers in boreal Alberta will likely depend on the presence of both old-growth and recently burned coniferous forests or forests with old-growth structural characteristics. Black-backed woodpeckers appear to be more burn dependent than three-toeds, and their long-term persistence may depend on the frequency of recently burned forests within their dispersal range.

A comparison of impact measures from hybrid and synthetic techniques: A case study of the Foothills Model Forest

This article presents an applied framework for selective precision in the insertion of superior data into hybrid regional models where regional purchasing coefficients are absent or unattainable. Due to the lack of regional-level data, crude top-down methods are the most frequently applied methods in Canadian regional studies. However, they may lead to inaccurate policy analysis where significant variation exists between the technical coefficients and trade flows of two economies. This article discusses an alternative, hybrid approach that involves the collection of region-specific information and therefore promises greater accuracy and validity of impact analysis. The robustness of the hybrid model is tested against the results derived from a synthetically regionalized model. The Foothills Model Forest (FMF) in west-central Alberta is used as a case study for the development of a sub-provincial economic database for the purpose of regional impact modeling.

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

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.

Quantifying barrier effects of roads and seismic lines on movements of female woodland caribou in northeastern Alberta

Linear developments such as roads, seismic lines, and pipeline rights-of-way are common anthropogenic features in the boreal forest of Alberta. These features may act as barriers to the movement of threatened woodland caribou (Rangifer tarandus caribou). Thirty-six woodland caribou were captured and fitted with global positioning system collars. These collared caribou yielded 43 415 locations during the 12-month study period. We compared rates of crossing roads and seismic lines with rates at which caribou crossed simulated roads and seismic lines created using ArcInfo GIS. Seismic lines were not barriers to caribou movements, whereas roads with moderate vehicle traffic acted as semipermeable barriers to caribou movements. The greatest barrier effects were evident during late winter, when caribou crossed actual roads 6 times less frequently than simulated road networks. Semipermeable barrier effects may exacerbate functional habitat loss demonstrated through avoidance behaviour. This novel approach represents an important development in the burgeoning field of road ecology and has great potential for use in validating animal-movement models.

Microbial activity, nutrient dynamics and litter decomposition in a Canadian Rocky Mountain pine forest as affected by N and P fertilizers

To study the specific effects of N and P fertilizers on soil microbial processes under field conditions, a pine forest in southern Alberta was fertilized with ammonium nitrate and urea (0 and 188 kg N ha −1, respectively) singly and in combination with triple super phosphate (0 and 94 kg P ha −1, respectively). Microbial respiration (BR), substrate induced respiration (SIR), metabolic quotient (qCO 2) and rates of microbially mediated key processes were monitored in the forest floor FH material during the growing periods of spring 1990 to fall 1992. A transient increase in soil NH 4 + availability was detected following N addition but significant increases in PO 4 3− availability were detected throughout the study as a result of P enhancement. Microbial variables were unaffected by N addition, whereas soil organic matter and SIR was increased with P fertilization. Microbial BR and qCO 2 were reduced with P fertilization suggesting more efficient utilization of C. Increased net mineralization of P in the P-fertilized plots was found during the second and third summers after fertilization, following immobilization of P during the first year. In contrast, NH 4 +-N mineralization in the N-fertilized plots was significantly increased only during the first year. Rates of nitrification were unaffected by either N or P addition. Decomposition of pine litter was enhanced with N addition only during the first year and P had no effect on decomposition. Addition of N and P at these rates does not appear to impose a major ecological stress to the soil ecosystem.

Use of holomorph characters to delimit Microascus nidicola and M. soppii sp. nov., with notes on the genus Pithoascus

Several isolates of a perithecial microascaceous ascomycete having falcate ascospores and a Scopulariopsis anamorph were obtained from rotting wood in the boreal forest of Alberta, Canada. Additional isolates appeared conspecific based on anamorphic characters, but failed to produce a teleomorph. These isolates showed similarities to Microascus nidicola (type species of the genus Pithoascus) and Scopulariopsis flava. Sexual compatibility systems were investigated to establish holomorph concepts for these taxa. The teleomorph obtained in mating trials among anamorphic isolates was identical to that of self-fertile isolates. The new heterothallic species M. soppii is described. The anamorph is S. soppii. Single ascospore isolates derived from M. nidicola demonstrated homothallism and lacked an anamorph. Scopulariopsis flava (basionym Acaulium flavum) is considered a nomen dubium. Generic concepts of Pithoascus are evaluated and the genus is treated as a synonym of Microascus. Pithoascus stoveri is transferred as M. stoveri comb. nov.

Structure and composition of edges next to regenerating clear‐cuts in mixed‐wood boreal forest

Abstract. We investigated the spatial and temporal pattern of edge influence on primary (forest structure) and secondary (understory structure and composition) responses at forest edges next to regenerating clear‐cuts in Populus‐dominated boreal forest in Alberta, Canada. We used before/after‐harvest comparisons to determine whether there were significant effects of edge creation in the first and second year after harvest. We also investigated 5‐ and 16‐yr‐old edges to determine whether their structure and composition were significantly different from interior forest. Distance of edge influence (20–60 m) was not extensive compared to findings from studies conducted in other forest types. In the first two years after harvest, there were significant primary responses to edge creation including increased tree mortality, snag breakage and amount of downed coarse woody debris; as well as secondary responses including prolific vegetative regeneration of Populus spp. and a decrease in total shrub cover. Significant edge effects were still detectable 5 and 16 yr after edge creation, despite the rapid regeneration of Populus‐ dominated forest in the adjacent clear‐cuts. These older edges showed evidence of past primary and secondary responses, including a more heterogeneous canopy, along with additional changes in under‐ story composition. At both younger and older edges the distance of edge influence was greater for secondary responses (up to 60 m) than for primary responses (10–20 m). We hypothesize that secondary responses to edge creation start later than primary responses and that the distance of edge influence is greater for secondary (vs. primary) responses.

Alberta Research Council: Providing innovation from the forest to the finishing line

The Alberta Research Council (ARC) delivers public good research and development (R&D), contract services and technology commercialization to the forest sector. Alberta's forest sector has identified three major research and technology thrusts: sustainable forest management, adding value to the forest resources, and enabling technologies for improved management, resource processing and environmental protection. Issues such as fibre supply and utilization, energy conservation, certification and technology transfer are priorities. ARC's Forest Technologies Division addresses these priorities by providing public and private sector customers with applied research and technology services via its three business units: Forest Resources, Forest Products, and Pulp and Paper. Key words: Alberta Research Council, public good applied research and development, contract services, technology commercialization, sustainable forest management, agrifibres, pulp and paper, forest products, engineered wood composites

Structure and composition of edges next to regenerating clear-cuts in mixed-wood boreal forest

Abstract. We investigated the spatial and temporal pattern of edge influence on primary (forest structure) and secondary (understory structure and composition) responses at forest edges next to regenerating clear-cuts in Populus-dominated boreal forest in Alberta, Canada. We used before/after-harvest comparisons to determine whether there were significant effects of edge creation in the first and second year after harvest. We also investigated 5- and 16-yr-old edges to determine whether their structure and composition were significantly different from interior forest. Distance of edge influence (20–60 m) was not extensive compared to findings from studies conducted in other forest types. In the first two years after harvest, there were significant primary responses to edge creation including increased tree mortality, snag breakage and amount of downed coarse woody debris; as well as secondary responses including prolific vegetative regeneration of Populus spp. and a decrease in total shrub cover. Significant edge effects were still detectable 5 and 16 yr after edge creation, despite the rapid regeneration of Populus- dominated forest in the adjacent clear-cuts. These older edges showed evidence of past primary and secondary responses, including a more heterogeneous canopy, along with additional changes in under- story composition. At both younger and older edges the distance of edge influence was greater for secondary responses (up to 60 m) than for primary responses (10–20 m). We hypothesize that secondary responses to edge creation start later than primary responses and that the distance of edge influence is greater for secondary (vs. primary) responses.

Interactions among young stages of the wolf spiders Pardosamoesta and P. mackenziana (Araneae: Lycosidae)

Young stages of the wolf spiders Pardosamoesta and P. mackenziana coexist on the forest floor in a deciduous forest in central Alberta, yet nothing is known of the potential interactions between and among these ubiquitous species. An experiment, using a series of 0.25‐m2 arenas, was designed to test for inter‐ and intraspecific exploitative competition. Experimental treatments were established in the arenas in late July. Treatments involved stocking recently hatched spiderlings of each species alone, and with both species together at natural (10 spiderlings per arena) and two times the natural densities. In September the arenas were searched for Pardosa spiderlings, and the survival and mass gain of each species were determined. Other predatory arthropods, and Collembola, a common prey of young wolf spiders, were counted in the arenas before the experimental treatments were established and at the end of the experiment. No evidence for competitive interactions was uncovered, but spiderling survival was 29% for P. moesta and 20% for P. mackenziana, suggesting other mortality factors (e.g., cannibalism, intraguild predation) may be important. Top‐down effects (predatory arthropods) had no effect on Pardosa survival. Bottom‐up effects, however, were significant as treatments containing spiderlings had fewer Collembola compared to control arenas, further supporting the importance of spiders in leaf‐litter food webs.

Songbird communities in a pyrogenic habitat mosaic

Wildfires play a key role in shaping the boreal forest landscape, yet the response of wildlife to the patchy mosaics they create is poorly understood. We studied songbirds 5–6 years post-fire in a large burn (9600 ha) in the boreal mixed wood forest of north-eastern Alberta. In the spring of 1995 and 1996 we estimated abundance of songbirds in four areas, each with four replicate sites: unburned patches within the fire (Isolates); burned patches (Burns); patches that had been clear-cut prior to burning by wildfire (Cut-Burns); and the unburned, continuous forest adjacent to the burn (Peripherals). We also sampled shrub-based arthropods with sweep-nets at each site. To investigate the role of Isolates, we compared them to Peripherals and to Burns. We compared Cut-Burns to Burns to examine the effect of logging prior to burning. In general, Isolates supported higher numbers of species and individuals than Peripherals, mainly due to higher numbers of aerial-foraging birds. Isolates and Burns had similar species richness and abundance, but Burns supported more aerial foragers while Isolates had more foliage gleaners. Cut-Burns generally supported fewer individuals than Burns, in particular fewer shrub-nesters, aerial foragers, and neotropical migrants. More bird species reached their highest densities in Burns than in any other area. Songbird species richness and abundance were positively related to dry arthropod biomass, with Burns and Isolates having the highest arthropod biomass. These patterns indicated that, 5–6 years post-burn, the patchy mosaic created by this wildfire supported more species than the mature forest surrounding the fire. Clear-cut logging prior to burning resulted in a diminished songbird community compared to that found in burned stands.

Cost-effective Sampling Design Applied to Large-scale Monitoring of Boreal Birds

Despite their important roles in biodiversity conservation, large-scale ecological monitoring programs are scarce, in large part due to the difficulty of achieving an effective design under fiscal constraints. Using long-term avian monitoring in the boreal forest of Alberta, Canada as an example, we present a methodology that uses power analysis, statistical modeling, and partial derivatives to identify cost-effective sampling strategies for ecological monitoring programs. Empirical parameter estimates were used in simulations that estimated the power of sampling designs to detect trend in a variety of species' populations and community metrics. The ability to detect trend with increased sample effort depended on the monitoring target's variability and how effort was allocated to sampling parameters. Power estimates were used to develop nonlinear models of the relationship between sample effort and power. A cost model was also developed, and partial derivatives of the power and cost models were evaluated to identify two cost-effective avian sampling strategies. For decreasing sample error, sampling multiple plots at a site is preferable to multiple within-year visits to the site, and many sites should be sampled relatively infrequently rather than sampling few sites frequently, although the importance of frequent sampling increases for variable targets. We end by stressing the need for long-term, spatially extensive data for additional taxa, and by introducing optimal design as an alternative to power analysis for the evaluation of ecological monitoring program designs.

Predicting natural regeneration of white spruce in boreal mixedwood understories

Successful mixedwood management in the boreal forest of Alberta requires better knowledge of the occurrence and success of natural white spruce regeneration. In this study we developed statistical models to predict the natural establishment and height growth of understory white spruce (Picea glauca (Moench) Voss) in the boreal mixedwood forest in Alberta using data from 148 provincial permanent sample plots, supplemented by measurements of the amount and height growth of regenerating white spruce, and the amount and type of available substrate. A discriminant model correctly classified 73% of the sites as to presence or absence of a white spruce understory based on the amount of spruce basal area, rotten wood, ecological nutrient regime, soil clay fraction and elevation, although it explained only 30% of the variation in the data. On sites with a white spruce understory, a regression model related the abundance of regeneration to rotten wood cover, spruce basal area, pine basal area, soil clay fraction, and grass cover (R2 = 0.36). About half of the seedlings surveyed grew on rotten wood, and only 3% on mineral soil, and seedlings were 10 times more likely to have established on these substrates than on litter. Exposed mineral soil was rare, covering only 0.3% of the observed transect area, rotten wood covered 4.5%, and litter/undisturbed forest floor covered the remainder. The regression models developed for average relative height growth rate included feather moss cover, stand age and birch basal area for seedlings ≤ 1 m (R2 = 0.23), and feather moss cover, elevation, other moss cover and soil clay fraction for seedlings between 1 m and 3 m (R2 = 0.27). Key words: Picea glauca, seedling establishment, seedbeds, site factors, coarse woody debris, predictive models, mixedwood management

RESIDUAL TREE RETENTION AMELIORATES SHORT-TERM EFFECTS OF CLEAR-CUTTING ON SOME BOREAL SONGBIRDS

Retention of residual trees in “cutblocks,” logged blocks of forest, has been proposed as a method to conserve songbirds in landscapes fragmented by clear-cut logging. We examined songbird communities in the boreal mixed-wood forest of Alberta, Canada, to investigate the effect on songbird abundance of (1) logging and (2) retaining variable densities of residual trees in cutblocks (10–133 trees/ha or basal area of 0.50–10.65 m2). We surveyed songbirds in logged and forested, aspen-dominated, mixed-wood stands in the year before, the year after, and three years after logging. We analyzed changes in abundance of 27 common songbird species: 23 present in the forest prior to logging and four that appeared after logging. Ten species declined with logging and were termed “forest species.” Ten more species did not change with logging and were called “habitat generalists.” The seven species that increased with logging were called “cutblock species.” When the effect of residual tree retention was examined in terms of basal area (rather than density) of residual trees, more songbird species were found to be both positively and negatively affected by residual tree retention, despite the fact that the two tree measures were highly correlated. In the first year after logging, four bird species (two forest, one generalist, and one cutblock) increased, and none decreased with increasing residual tree retention in cutblocks. In the third year after logging, again four species increased with increasing retention, but these were different species than in the first year after logging (one forest and three generalist species). Furthermore, four cutblock species decreased with increasing retention. Based on these findings, we conclude that retention of residual trees may be beneficial to some species, although conservation of unlogged reserves is also important. Most importantly, we recommend that research be continued to examine a larger range of tree retention and longer term effects on the avifauna.

Residual Tree Retention Ameliorates Short-Term Effects of Clear-Cutting on Some Boreal Songbirds

Retention of residual trees in “cutblocks,” logged blocks of forest, has been proposed as a method to conserve songbirds in landscapes fragmented by clear-cut logging. We examined songbird communities in the boreal mixed-wood forest of Alberta, Canada, to investigate the effect on songbird abundance of (1) logging and (2) retaining variable densities of residual trees in cutblocks (10–133 trees/ha or basal area of 0.50–10.65 m2). We surveyed songbirds in logged and forested, aspen-dominated, mixed-wood stands in the year before, the year after, and three years after logging. We analyzed changes in abundance of 27 common songbird species: 23 present in the forest prior to logging and four that appeared after logging. Ten species declined with logging and were termed “forest species.” Ten more species did not change with logging and were called “habitat generalists.” The seven species that increased with logging were called “cutblock species.” When the effect of residual tree retention was examined in terms of basal area (rather than density) of residual trees, more songbird species were found to be both positively and negatively affected by residual tree retention, despite the fact that the two tree measures were highly correlated. In the first year after logging, four bird species (two forest, one generalist, and one cutblock) increased, and none decreased with increasing residual tree retention in cutblocks. In the third year after logging, again four species increased with increasing retention, but these were different species than in the first year after logging (one forest and three generalist species). Furthermore, four cutblock species decreased with increasing retention. Based on these findings, we conclude that retention of residual trees may be beneficial to some species, although conservation of unlogged reserves is also important. Most importantly, we recommend that research be continued to examine a larger range of tree retention and longer term effects on the avifauna.

Spiders (Araneae) associated with downed woody material in a deciduous forest in central Alberta, Canada

Abstract1 Spiders (Araneae) were collected on and near downed woody material (DWM) in a Populus‐dominated forest to determine if spiders utilize wood surfaces, and to ascertain the importance of DWM habitat and wood elevation for spider assemblages.2 Over 10 000 spiders representing 100 species were collected. Although more spiders were collected on the forest floor, spider diversity was higher in traps located on wood surfaces than on the forest floor, and 11 species were collected more frequently on wood surfaces.3 Spiders utilized DWM at different stages in their development. Female Pardosa mackenziana (Keyserling) (Lycosidae) carrying egg sacs were caught most often on the surface of DWM, possibly to sun their egg sacs. Additionally, the proportion of immature spiders was higher on the wood surface than on the forest floor.4 Spiders collected on logs with and without bark were compared to assemblages collected on telephone poles to assess what features of DWM habitat may be important. Web‐building species were seldom collected on telephone poles, suggesting that they depend on the greater habitat complexity provided by DWM. In contrast, hunting spiders did not distinguish between telephone poles and logs.5 Fewer spiders and a less diverse fauna utilized elevated compared to ground‐level wood. Additionally, Detrended Correspondence Analysis revealed that the spider community from elevated wood was distinguishable from the spider community from ground‐level wood, and from the forest floor spider community.

Sheep grazing for vegetation management in the northern forests of British Columbia and Alberta

Vegetation management treatments are applied on a large proportion of regenerated sites in British Columbia and Alberta to improve survival and early growth of conifers and to meet provincial standards. Conventional techniques like manual brushing and chemical herbicides continue to be widely applied. However, other less familiar methods like sheep grazing can also be a viable option on some sites. Sheep grazing has been demonstrated to offer good to excellent control of both herbaceous and woody vegetation, provided certain conditions are met. Specifically, the dominant vegetation must be palatable to the sheep, the large- and small-scale topography must be relatively even, the treatment must be carried out before the crop trees become severely suppressed or damaged and the animals must be effectively supervised. It is our position that there is an opportunity to increase the use of sheep grazing for vegetation control in some regions of the northern forests of British Columbia and Alberta, thus providing another viable option for forest managers. Key words: sheep, grazing, vegetation management, plantation establishment, conifer release, northern forest

A parametric model of the fire-size distribution

This paper developes statistical models of the size distribution of lightning-caused wildfires in the boreal mixedwood forests of Alberta, Canada, for the intervals 1980––1998 and 1961––1998. Above any minimum threshold size [Formula: see text]3 ha, the logarithm of fire size is approximately exponentially distributed. However, computer simulations using the best-fit distribution would over predict the frequency of large fires, and thus the mean rate of disturbance. A truncated exponential distribution, which places an upper bound on fire size, is more suitable and, according to probability plots, provides an excellent fit to the data. I estimate the maximum fire size in the study area to be [Formula: see text] 650 000 ha. This estimate is insensitive to the choice of lower bound for fire sizes (between 3 and 1000 ha) and to the choice of sampling interval. Parametric modelling of fire sizes using covariates derived from forest inventory data shows that the expected size of a fire is positively related to the abundance of pine forest in the vicinity of the point of detection and negatively related to the abundance of recently logged or burnt areas. This implies that variation in forest structure and disturbance history impose marked spatial variability on the fire size distribution. Other covariates, such as periodic indices of fire weather, could readily be evaluated in this framework.

The influence of clear-cut logging and residual leave material on small mammal populations in aspen-dominated boreal mixedwoods

We investigated responses of populations of common small mammals to variation in the amount of standing trees and residual woody material retained during logging in aspen-dominated, boreal mixedwood forest in north-central Alberta. Experimentally manipulated levels of residual material, with two replicates per level, were (i) "zero residual": clear-cut and no woody debris (tree tops and limbs); (ii) "low residual": clear-cut and woody debris; (iii) "moderate residual": 10% basal area standing live tree retention, and woody debris; and (iv) "uncut": 100% uncut. Patterns of small mammal abundance were similar throughout the study on uncut and moderate-residual grids, where southern red-backed voles (Clethrionomys gapperi Vigors) and deer mice (Peromyscus maniculatus Wagner) were numerically dominant. In contrast, C. gapperi were virtually absent from the low- and zero-residual grids during the breeding season following logging and occurred at low numbers in the following 2 years. Peromyscus maniculatus were common on low- and zero-residual grids in all years. We found no evidence that rates of reproductive activity and (or) survival in C. gapperi and P. maniculatus were affected by logging treatments. Meadow voles (Microtus pennsylvanicus Ord) were uncommon on uncut and moderate-residual grids throughout the study but were abundant on both low-residual grids and one zero-residual grid, particularly in the second year following logging, when they exhibited irruptive dynamics in midsummer. In sum, relative abundances of common small mammals were most affected by intensive (clear-cut) logging, and our results suggest that the experimental retention of at least 10% basal area on cutovers may reduce some of these effects.