Climate change is predicted to increase rates of fire activity in boreal forests. A shortened fire return interval may result in different outcomes of community structure in the northern boreal forest, since the age of a forest influences seed production and potential post-fire regeneration. With two closely timed fires, dominant boreal conifers such as black spruce (Picea mariana) may be vulnerable to regeneration failures after fire because of the long time required to reach reproductive maturity. I report on the relationship between stand age and seed productivity of black spruce in northern Yukon Territory and central Alaska. I used fire history maps to select sites of various stand ages, including stand ages that would occur in a short fire return interval (less than 80 years) versus longer fire intervals (up to 200 years). At each site, I measured stand density and basal area using the point-center-quarter method. Ten black spruce trees were randomly selected for cone surveys and age analysis. I also selected a subset of five trees for detailed analyses of cone and seed production within yearly cohorts. The results of this study illustrate the strong relationships between stand age and stand basal area with cone and seed production of northern black spruce. The resulting equations can be used to predict the seed capacity and regeneration potential of black spruce stands with known stand basal area or stand age. I estimate, along with the number of seeds required to produce a two year old black spruce seedling on high quality seedbeds, stands burned at an age less than 50 years will likely have reduced black spruce post-fire density. On low quality seedbeds, black spruce forests are more vulnerable to regeneration failures and fire cycles less than 150 years are likely to result in reduced recruitment. Under a shortened fire return interval these northern black spruce forests are likely to have reduced post-fire density.

Worldwide, riparian areas are considered among the most biologically productive and species-rich habitats on the landscape and provide important breeding areas for many bird species. In the Boreal Plain ecozone of western Canada, forests adjacent to riparian areas are generally protected from forest harvesting through the retention of treed buffer strips. <p>Riparian buffer strips are expected to provide habitat for wildlife including many passerine bird species. Recently, non-conventional methods of riparian management have been implemented in parts of the Boreal Plain with the intent of aligning forestry more closely with natural disturbance processes. How bird communities associated with these management scenarios diverge from natural disturbances and how riparian birds interact with disturbances in the adjacent upland habitat are key questions in the conservation of boreal riparian bird communities. To answer these questions, I surveyed birds inhabiting riparian areas with adjacent naturally disturbed (burned) and harvested forest to determine how bird communities differ early (1-5 years) post-disturbance and, separately, in a before-and-after harvesting study. <p>Riparian species associated with burned merchantable shoreline forests and riparian areas included Common Yellowthroat (<i>Geothlypis trichas</i>) and Eastern Kingbird (<i>Tyrannus tyrannus</i>). Le Contes Sparrow (<i>Ammodramus leconteii</i>) was associated with burned riparian habitats adjacent to non-merchantable forests (e.g., bog, fen), while Alder Flycatcher (<i>Empidonax alnorum</i>) and Wilsons Warbler (<i>Wilsonia pusilla</i>) were indicative of harvested sites with larger buffers (30 m). Riparian species richness was highest in burned non-merchantable sites. Multivariate Redundancy Analysis of post-disturbance bird communities showed greater divergence in overall (riparian and upland) community composition than one with only riparian species. This suggests reduced sensitivity of riparian birds to disturbances in forested areas compared to upland bird communities. However, a higher natural range of variability was exhibited in riparian bird community composition in post-fire sites than in post-harvested sites. This emphasizes that forest management practices do not currently fully approximate natural disturbance for boreal riparian birds. <p>To assess the response of bird communities in riparian habitats to forestry, I studied bird communities one year (2004) prior to forest harvest and two years (2005 and 2006) after harvest. One of three treatments, 1) 5-35% retention (0 m buffer), 2) 35-75% retention (10 m buffer with variable retention in the next 30 m), 3) 75-100% retention (50 m buffer) and unharvested reference sites, was randomly assigned to 34 wetlands. Treatments were designed to represent buffer management strategies currently applied in the Boreal Plain. Eight of 22 species showed a significant response (p<0.1) to treatment, year or year*treatment effects including two riparian species, the Common Yellowthroat and Song Sparrow (<i>Melospiza melodia</i>) that increased in abundance in harvested sites. Overall pre-disturbance communities diverged (p<0.05) over the three-year study period as shown using Multiple-response Permutation Procedures (MRPP). However, riparian bird communities did not diverge from pre-disturbance or from reference sites providing further evidence that riparian bird communities are less impacted by forestry in the adjacent upland habitats than overall bird communities. Therefore, alternative forest harvesting methods should be explored that encompass landscape-scale management including total buffer removal to maximize conservation objectives for boreal forest bird communities while attempting to maintain natural disturbance processes.

In an attempt to manage values other than timber production, forestry companies have sought a new paradigm to manage forest resources. Based on the hypothesis that wildlife in the boreal forest has adapted to habitat structures created by natural disturbances, some forest harvests have been modified to approximate patterns left after natural disturbance. Attempts at approximating natural disturbance have included retention of patches of live trees within cutblock boundaries, cutting to natural stand boundaries and application of harvest plans with spatio-temporally aggregated cutblocks (single-pass harvests). Single-pass harvesting is a recent attempt to better approximate natural disturbance in the boreal and has not been evaluated for its potential to sustain wildlife. I therefore contrasted residual patch pattern and composition, as well as landscape-scale avian abundance and composition in 1) single-pass; 2) multi-pass; and 3) salvage logged post-fire harvests, and contrasted these with unsalvaged post-fire sites. Post-fire sites were used to define the Natural Range of Variation (NRV). Seventy-two plots (12 post-fire, 15 post-salvage harvest, 16 single-pass harvest, and 29 multi-pass harvest) were surveyed for avian community composition and abundance one to five years post disturbance. <p>I contrasted the composition of remaining live forest stands at the landscape-scale and in residual patches by pairwise comparison of pre- and post-disturbance composition. At the landscape-scale, non-metric mutlidimensional scaling suggested post-disturbance landscape composition of post-fire and salvage-logged plots was similar to pre-disturbance landscape composition, with a tendency toward greater survival of hardwoods and lower survival of jack pine (Pinus banksiana) or black spruce (Picea mariana). However, harvesting of hardwoods and mixedwood stand types in single and multi-pass harvests led to landscapes with more bog and swamp habitats. <p>Comparison of residual patch composition with pre-disturbance composition was made using blocked multi-response permutation procedures. Post-fire plots (i.e. NRV) had residual patches that were representative of pre-disturbance composition, but with slightly more hardwoods and less black spruce/jack pine than expected by chance. All harvested treatments had similar biases among residuals to those left by fire, except that multi-pass harvests tended to leave less mixedwood habitat than expected. Multi-pass harvests also had less area in residual patches, and patches were smaller, more isolated and less complex in shape. Single-pass harvests had residual patches that were more representative of the size, shape, complexity, and change in composition seen post-fire. Multi-pass harvests only had 14% of the residual patch area in patches at least 5 ha in size, whereas this proportion was higher in fire (83%), salvage-logged areas (42%), and single-pass harvests (57%). Old-growth associated species might only persist in patches 5 ha or larger, and so multi-pass harvesting may have negative consequences for these forest birds.<p>Redundancy analysis indicated that bird communities differed from the NRV in all harvest treatments. However, single-pass harvests provided a slightly better fit to NRV than did multi-pass harvesting. Community similarity was influenced by non-linear responses to area harvested, residual retention, residual composition and pre-disturbance forest composition. An optimization routine was used to select harvest characteristics that would maximize community similarity to NRV. Optimization suggested that community similarity to NRV can be maximized by using single-pass harvests over multi-pass harvests, harvesting 66-88% of of a planning unit, and retaining 5-19% of the harvest area as live residual patches.<p>My results suggest that single-pass harvesting may be ecologically more sustainable than multi-pass harvests. Future studies are required to determine whether both harvesting treatments converge with NRV through time. Greater overlap of salvage-logged avian communities with NRV suggests that experimentation with prescribed fire as a post-harvest treatment may be the best method to bring harvests ecologically closer to NRV, and highlights the need to conserve early post-fire habitats.

An archaeological survey was conducted in the Clearwater River Valley, Saskatchewan in the summer of 2008 by University of Saskatchewan Masters student Alan Korejbo and a crew of three. Prior to this project, only three sites had been recorded along this 55 km portion of the river. Researching this remote wilderness heritage river in the boreal ecoregion presented substantial logistical barriers; nonetheless, a total of seventeen sites, mostly precontact in nature, were discovered. The density of sites identified in this survey suggests that this region is archaeologically rich; thus, meriting future research. Information collected from this encourages vigorous archaeological resource management in the Clearwater River Provincial Park. Data from this survey may give future researchers a basis from which to start. Survey results and previous research are combined to hypothesize past land usage in northwestern Saskatchewan. Furthermore, coupled with previous research, the data from this project may allow us to suggest possible cultural influence and interaction and ask pertinent questions that may aid in future research here.

An archaeological survey was conducted in the Clearwater River Valley, Saskatchewan in the summer of 2008 by University of Saskatchewan Masters student Alan Korejbo and a crew of three. Prior to this project, only three sites had been recorded along this 55 km portion of the river. Researching this remote wilderness heritage river in the boreal ecoregion presented substantial logistical barriers; nonetheless, a total of seventeen sites, mostly precontact in nature, were discovered. The density of sites identified in this survey suggests that this region is archaeologically rich; thus, meriting future research. Information collected from this encourages vigorous archaeological resource management in the Clearwater River Provincial Park. Data from this survey may give future researchers a basis from which to start. Survey results and previous research are combined to hypothesize past land usage in northwestern Saskatchewan. Furthermore, coupled with previous research, the data from this project may allow us to suggest possible cultural influence and interaction and ask pertinent questions that may aid in future research here.

While boreal forest habitats have historically been relatively free from invasive plants, there have been recent increases in the diversity and range of invasive plants in Alaska. It is critical that we understand how disturbances influence invasibility in northern boreal forests, to avoid the economic damage other regions have experienced from invasive plants. Black spruce (Picea mariana) is the dominant forest type in interior Alaska, and wildfire is the dominant disturbance in these forests. Furthermore, disturbances in the form of management for fire suppression are common in forests close to urban areas. I surveyed recently burned, managed, and undisturbed black spruce forests for invasive plants to determine if fire and management facilitate invasive plant colonization. I also conducted an experimental seeding trial with three invasive plants common to Alaska (bird vetch (Vicia cracca), common dandelion (Taraxacum officinale), and white sweetclover (Melilotus officinalis) in burned and mature black spruce forest to determine if fire facilitates invasive plant germination. To determine the effect of substrate type on invasive plant germination, I planted seeds on a variety of substrates in the burned forest. Results indicate that fire and fire suppression treatments promote invasive plant colonization, as invasive plants were observed in burned and managed areas, but not in mature stands. Analysis of environmental data taken at survey sites indicate that fire mediates invasibility through its effects on substrate quality. In burned stands, invasive plants are most likely to colonize areas of shallow post-fire organic depth. Results from the seeding trials were consistent with results from invasive plant surveys, with reduced germination in mature compared to burned forest, and no germination on the residual organic layer in the burned forest. The highest germination occurred on mineral soil in burned forest, indicating that severe fires that combust the organic layer are likely to increase invasibility. The results of this study suggest that invasive species control efforts should be prioritized to disturbed forests, particularly areas where the disturbance has exposed mineral soil.

As the past century’s technological development has progressed the Swedish boreal forests have transformed into dense, highly productive, homogenous and coniferous forests. The area around Saxdalen in Ludvika municipality has long been dominated forests which have been heavily worked since the 18th century. There are in Ludvika 119 000 hectares of productive forest land. Around 70 percent are owned by forest companies and 20 by private forest owners. The forestry is governed by national laws and instructions from the Swedish Forest Agency. Foresters may also choose to abide by certification systems such as FSC and PEFC. 80 percent of Swedish productive forest is certified. This thesis is based on literature review and 8 field studies of regeneration fellings in Saxdalen. The purpose of this thesis is to understand to what degree environmental considerations are taken during regeneration fellings to preserve biodiversity. The focus of the thesis has been the preservation of storm sturdy trees, deciduous trees and standing dread trees, larger tree stumps and protected zones around watercourses. The protected zones were found severely lacking in practically all the observed fellings. The quality the trees preserved varied greatly between the fellings. In this study there were no found links between the ownership form or certification system and the considerations taken during regeneration fellings. A lot of parties are involved in fellings and those responsible aren’t always in full control. The work of preserving boreal forests resilience and biodiversity must be conducted in more strategic and coordinated fashion. There must be common criteria and strategies for large forest areas so that species can spread and survive the forestry, especially considering future climate change.

Worldwide, riparian areas are considered among the most biologically productive and species-rich habitats on the landscape and provide important breeding areas for many bird species. In the Boreal Plain ecozone of western Canada, forests adjacent to riparian areas are generally protected from forest harvesting through the retention of treed buffer strips. <p>Riparian buffer strips are expected to provide habitat for wildlife including many passerine bird species. Recently, non-conventional methods of riparian management have been implemented in parts of the Boreal Plain with the intent of aligning forestry more closely with natural disturbance processes. How bird communities associated with these management scenarios diverge from natural disturbances and how riparian birds interact with disturbances in the adjacent upland habitat are key questions in the conservation of boreal riparian bird communities. To answer these questions, I surveyed birds inhabiting riparian areas with adjacent naturally disturbed (burned) and harvested forest to determine how bird communities differ early (1-5 years) post-disturbance and, separately, in a before-and-after harvesting study. <p>Riparian species associated with burned merchantable shoreline forests and riparian areas included Common Yellowthroat (<i>Geothlypis trichas</i>) and Eastern Kingbird (<i>Tyrannus tyrannus</i>). Le Contes Sparrow (<i>Ammodramus leconteii</i>) was associated with burned riparian habitats adjacent to non-merchantable forests (e.g., bog, fen), while Alder Flycatcher (<i>Empidonax alnorum</i>) and Wilsons Warbler (<i>Wilsonia pusilla</i>) were indicative of harvested sites with larger buffers (30 m). Riparian species richness was highest in burned non-merchantable sites. Multivariate Redundancy Analysis of post-disturbance bird communities showed greater divergence in overall (riparian and upland) community composition than one with only riparian species. This suggests reduced sensitivity of riparian birds to disturbances in forested areas compared to upland bird communities. However, a higher natural range of variability was exhibited in riparian bird community composition in post-fire sites than in post-harvested sites. This emphasizes that forest management practices do not currently fully approximate natural disturbance for boreal riparian birds. <p>To assess the response of bird communities in riparian habitats to forestry, I studied bird communities one year (2004) prior to forest harvest and two years (2005 and 2006) after harvest. One of three treatments, 1) 5-35% retention (0 m buffer), 2) 35-75% retention (10 m buffer with variable retention in the next 30 m), 3) 75-100% retention (50 m buffer) and unharvested reference sites, was randomly assigned to 34 wetlands. Treatments were designed to represent buffer management strategies currently applied in the Boreal Plain. Eight of 22 species showed a significant response (p<0.1) to treatment, year or year*treatment effects including two riparian species, the Common Yellowthroat and Song Sparrow (<i>Melospiza melodia</i>) that increased in abundance in harvested sites. Overall pre-disturbance communities diverged (p<0.05) over the three-year study period as shown using Multiple-response Permutation Procedures (MRPP). However, riparian bird communities did not diverge from pre-disturbance or from reference sites providing further evidence that riparian bird communities are less impacted by forestry in the adjacent upland habitats than overall bird communities. Therefore, alternative forest harvesting methods should be explored that encompass landscape-scale management including total buffer removal to maximize conservation objectives for boreal forest bird communities while attempting to maintain natural disturbance processes.

In an attempt to manage values other than timber production, forestry companies have sought a new paradigm to manage forest resources. Based on the hypothesis that wildlife in the boreal forest has adapted to habitat structures created by natural disturbances, some forest harvests have been modified to approximate patterns left after natural disturbance. Attempts at approximating natural disturbance have included retention of patches of live trees within cutblock boundaries, cutting to natural stand boundaries and application of harvest plans with spatio-temporally aggregated cutblocks (single-pass harvests). Single-pass harvesting is a recent attempt to better approximate natural disturbance in the boreal and has not been evaluated for its potential to sustain wildlife. I therefore contrasted residual patch pattern and composition, as well as landscape-scale avian abundance and composition in 1) single-pass; 2) multi-pass; and 3) salvage logged post-fire harvests, and contrasted these with unsalvaged post-fire sites. Post-fire sites were used to define the Natural Range of Variation (NRV). Seventy-two plots (12 post-fire, 15 post-salvage harvest, 16 single-pass harvest, and 29 multi-pass harvest) were surveyed for avian community composition and abundance one to five years post disturbance. <p>I contrasted the composition of remaining live forest stands at the landscape-scale and in residual patches by pairwise comparison of pre- and post-disturbance composition. At the landscape-scale, non-metric mutlidimensional scaling suggested post-disturbance landscape composition of post-fire and salvage-logged plots was similar to pre-disturbance landscape composition, with a tendency toward greater survival of hardwoods and lower survival of jack pine (Pinus banksiana) or black spruce (Picea mariana). However, harvesting of hardwoods and mixedwood stand types in single and multi-pass harvests led to landscapes with more bog and swamp habitats. <p>Comparison of residual patch composition with pre-disturbance composition was made using blocked multi-response permutation procedures. Post-fire plots (i.e. NRV) had residual patches that were representative of pre-disturbance composition, but with slightly more hardwoods and less black spruce/jack pine than expected by chance. All harvested treatments had similar biases among residuals to those left by fire, except that multi-pass harvests tended to leave less mixedwood habitat than expected. Multi-pass harvests also had less area in residual patches, and patches were smaller, more isolated and less complex in shape. Single-pass harvests had residual patches that were more representative of the size, shape, complexity, and change in composition seen post-fire. Multi-pass harvests only had 14% of the residual patch area in patches at least 5 ha in size, whereas this proportion was higher in fire (83%), salvage-logged areas (42%), and single-pass harvests (57%). Old-growth associated species might only persist in patches 5 ha or larger, and so multi-pass harvesting may have negative consequences for these forest birds.<p>Redundancy analysis indicated that bird communities differed from the NRV in all harvest treatments. However, single-pass harvests provided a slightly better fit to NRV than did multi-pass harvesting. Community similarity was influenced by non-linear responses to area harvested, residual retention, residual composition and pre-disturbance forest composition. An optimization routine was used to select harvest characteristics that would maximize community similarity to NRV. Optimization suggested that community similarity to NRV can be maximized by using single-pass harvests over multi-pass harvests, harvesting 66-88% of of a planning unit, and retaining 5-19% of the harvest area as live residual patches.<p>My results suggest that single-pass harvesting may be ecologically more sustainable than multi-pass harvests. Future studies are required to determine whether both harvesting treatments converge with NRV through time. Greater overlap of salvage-logged avian communities with NRV suggests that experimentation with prescribed fire as a post-harvest treatment may be the best method to bring harvests ecologically closer to NRV, and highlights the need to conserve early post-fire habitats.

Climate change is predicted to increase rates of fire activity in boreal forests. A shortened fire return interval may result in different outcomes of community structure in the northern boreal forest, since the age of a forest influences seed production and potential post-fire regeneration. With two closely timed fires, dominant boreal conifers such as black spruce (Picea mariana) may be vulnerable to regeneration failures after fire because of the long time required to reach reproductive maturity. I report on the relationship between stand age and seed productivity of black spruce in northern Yukon Territory and central Alaska. I used fire history maps to select sites of various stand ages, including stand ages that would occur in a short fire return interval (less than 80 years) versus longer fire intervals (up to 200 years). At each site, I measured stand density and basal area using the point-center-quarter method. Ten black spruce trees were randomly selected for cone surveys and age analysis. I also selected a subset of five trees for detailed analyses of cone and seed production within yearly cohorts. The results of this study illustrate the strong relationships between stand age and stand basal area with cone and seed production of northern black spruce. The resulting equations can be used to predict the seed capacity and regeneration potential of black spruce stands with known stand basal area or stand age. I estimate, along with the number of seeds required to produce a two year old black spruce seedling on high quality seedbeds, stands burned at an age less than 50 years will likely have reduced black spruce post-fire density. On low quality seedbeds, black spruce forests are more vulnerable to regeneration failures and fire cycles less than 150 years are likely to result in reduced recruitment. Under a shortened fire return interval these northern black spruce forests are likely to have reduced post-fire density.