Master in Forest Conservation (MFC) Capstone Papers

Permanent URI for this collectionhttps://hdl.handle.net/1807/71884

This collection houses capstone papers completed by students in Master in Forest Conservation program.
To obtain authorization to submit your paper to this collection, contact Laura Lapchinski or Sally Krigstin at Forestry.

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Now showing 1 - 20 of 167

A Review of Silvicultural Practices in Ontario Likely to Meet International Conservation Standards by Emulating Natural Disturbance
(2025) Osman, Halima; Caspersen, John
Canada has committed to the Kunming-Montreal Biodiversity Framework thereby agreeing to protect and conserve 30% of its land and oceans by 2030 (Government of Canada, 2022a; Government of Canada, 2023). To meet the objectives Canada must look towards innovative conservation strategies, such as Other Effective Area-Based Conservation Measures (OECMs). The goal of this study is to examine the potential for forests managed under Ontario’s sustainability standards, which include adaptive management practices that attempt to both conserving biodiversity and ensuring sustainable harvest levels to qualify as OECMs. This study compares these management guides with recent literature on ecological forestry and natural disturbance emulation to assess how well these practices conserve biodiversity long-term and to recommend modifications for enhancing their effectiveness. The results show that Ontario silviculture guides attempt to manage for biodiversity but often fall short of the standards associated with OECMs. However, current practices can be adjusted to better mimic disturbances and in turn enhance forest complexity and biodiversity, within managed forests. This study represents a first step toward identifying forestry practices that support in-situ conservation of biodiversity by mimicking natural disturbances, laying the foundation for future screening of these forests as potential OECMs.
Evaluating The Carbon Sequestration Potential of Young Urban Trees in Toronto, Canada.
(2025-01-07) Sewornu, Monique; Puric Mladenovic, Danijela
Planting and conserving urban trees are essential for mitigating climate change through carbon sequestration. While Toronto aims to expand its urban forest for climate resilience, most research has focused on mature trees, leaving a gap in understanding the carbon sequestration of young trees as they mature. This knowledge is essential for planning effective urban tree planting programs, as these young trees will be key to future carbon storage. The research was conducted in collaboration with the City of Toronto's Urban Forestry Department and the University of Toronto's Institute of Forestry to evaluate the carbon sequestration levels of 48 tree species planted in Toronto. This included streets (and residential areas) and parks to estimate how much carbon is sequestered in 10 and 20 years. A stratified random sampling was used to select trees planted in Toronto's streets and parks in 2022 and 2023, focusing on species with populations between 100 and 5,000 individuals. Tree data from the City of Toronto was imported into ArcGIS, where spatial analysis identified each tree's location, soil type (sandy or clay), and proximity to high-traffic roads. This setup enabled targeted field monitoring and ensured diverse urban conditions were represented. Field data collection took place from June 3rd to August 31st, 2024, covering 1,715 trees, of which 583 were park trees and 1,132 were street trees. At each site, we documented species, tree height, canopy base height, and caliper diameter for growth assessments. Canopy density was measured from four directions (N, S, E, W) to evaluate shading capabilities and tree health, with additional notes on stress indicators like damaged branches or crown dieback to understand the adaptation of young urban trees to Toronto's environment. Data was analyzed using the EPA guidelines for urban and suburban settings. The study showed that trees planted in 2022 are currently sequestering a total of 921.60 kg (streets) and 218.63 kg (parks) of carbon annually. By 2032 (10 years), these trees are projected to sequester 2,987.05 kg (streets) and 744.91 kg (parks) of carbon annually, with further growth leading to potential sequestration of 6,244.08 kg (streets) and 1,575.05 kg (parks) of carbon annually by 2042 (20 years). Furthermore, the trees planted in 2023 are currently sequestering a total of 478.59 kg (streets) and 403.27 kg (parks) of carbon annually. By 2033 (10 years), these trees are projected to sequester 2,133.47 kg (streets) and 1,808.05 kg (parks) of carbon annually, with further growth leading to potential sequestration of 4,669.60 kg (streets) and 3,811.86 kg (parks) of carbon annually by 2043 (20 years). This study recommends prioritizing fast-growing species for immediate carbon sequestration while incorporating slow-growing species for long-term benefits. Strategic planting should focus on street locations to enhance carbon capture. Regularly collecting data to monitor the CSP of the species in every five years may be essential for assessing tree health and carbon storage, alongside improved maintenance practices to optimize growth.
Exploring the Economic Costs and Carbon Sequestration Potential of Private Land Tree Planting Projects in Ontario: A Cost-Benefit Analysis
(2025-01) Wei, Grace; Yousefpour, Rasoul; Kaknevicius, Jessica
Rising carbon dioxide levels and climate change necessitate effective carbon mitigation strategies, with tree planting emerging as a dual solution for carbon sequestration and ecosystem restoration. In Ontario, Forests Canada’s 50 Million Tree Program (50MTP) supports private land tree planting projects, providing technical and financial assistance. This analysis examines the program’s financial costs and long-term carbon sequestration benefits, using data from 1,165 of the program’s projects and 43 species planted between 2023 and 2024. It assesses whether the current funding provided to landowners is adequate and examines the program’s long-term net benefits across different site classes, carbon pricing, and discount rates. The findings highlight significant societal benefits, with environmental gains consistently outweighing financial investments under a variety of scenarios. However, current funding levels are insufficient for covering the costs of tree establishment, emphasizing the need for increased investment to maximize the program’s impact.
Applying the 3-PG Model to Assess Carbon Sequestration and its Economic Impacts in Simcoe County Forest
(2025-01-07) Sun, Fanxuan; Yousefpour, Rasoul; Davis, Graeme
Tree Carbon Stock Changes under Thinning in Conifer Plantations: Insights from the Credit River Watershed
(2025-01-07) Ouyang, Haoyu; Puric-Mladenovic, Danijela
Thinning is an important forest management practice that affects stand structure and carbon dynamics. This study examined how thinning intensity and recovery period affect carbon stock and stand characteristics in coniferous plantations in the Credit River Basin of southern Ontario. Thinning enhances the ecological health and carbon sequestration potential of forests by changing competition and promoting growth. Stand structure variables such as tree diameter and height have a positive effect in driving carbon stock. Light thinning showed the greatest potential for increasing carbon stock, balancing resource availability and promoting growth. The results showed that thinning indirectly affected carbon accumulation by changing stand structure, and light thinning was the most suitable thinning intensity, primarily through its effect on large-diameter softwoods and hardwoods trees. The huge carbon stock contributed by large trees retained during thinning supports the adoption of irregular shelterwood systems and long-term monitoring and balanced forest management methods, which is of great significance for improving carbon stock and forest resilience in CVC coniferous plantations.
Risks and Potential Solutions of Developing Offsite Timber Construction in Ontario
(2024-12-25) Yifan, Cao; Rasoul, Yousefpour
Assessing the Viability of Skipping Tree Marking for Shelterwood System: A Comparative Study in Haliburton Forest
(2025-01-06) Zhang, Mengyuxin; Yousefpour, Rasoul
This study investigates the feasibility of eliminating tree marking in shelterwood systems by comparing marked and unmarked treatments in Haliburton Forest, Ontario. Key stand parameters, including residual basal area, seed tree basal area, and harvested volume, were assessed to evaluate silvicultural outcomes. Simulations using SORTIE-ND modeled the long-term impacts of tree selection practices over a 20-year period. The results revealed no statistically significant differences in any aspects of harvest outcome between marked and unmarked treatments. Although both failed to meet target residual basal area objectives, the unmarked treatment came closer to achieving these targets than the marked treatment. The results challenged the assumption that tree markers are inherently more reliable and highlighted the potential for replacing tree markers with loggers. Furthermore, advancements in technology, such as harvest algorithms and remote sensing, may provide viable alternatives to traditional tree selection methods in the future. This study also emphasizes the importance of establishing a network of marteloscopes in North America to enhance training, research, and collaboration, ensuring more consistent and informed decision-making in forest management practices.
Market Assessment of Cross-Laminated Timber (CLT) Fabricated from Red Pine in Ontario
(2025-01-07) Xiong, Yue; Yousefpour, Rasoul
Vegetation Community Response to Black Ash Decline in the Lake Simcoe Watershed
(2025) Manoharan, Hashveenah; Puric-Mladenovic, Danijela
Black ash (Fraxinus nigra Marsh.) is an endangered deciduous tree species in Ontario, Canada, threatened primarily by the invasive wood-boring emerald ash borer Fairmaire (Agrilus planipennis) (Coleoptera: Buprestidae). Black ash is a common swamp canopy species, and the loss of its presence in the forest canopy has been known to trigger ecosystem-scale changes in vegetation community structure and stand hydrology. This project aims to quantify the extent of black ash decline using permanent Vegetation Sampling Protocol (VSP) plots in the Lake Simcoe Region watershed, established in 2017 as part of the Lake Simcoe Protection Plan. VSP data is used to assess structural, hydrological, and vegetation responses to black ash loss over a 7 year time period (2017 to 2024). Results indicate a significant decline of black ash basal area and coverage in canopy and subcanopy layers, and small declines in shrub and groundcover layers. Plant species richness increased in these upper three layers, while species diversity remained relatively similar in all layers. Vegetation composition also remained relatively stable over the assessed period, with little evidence of major temporal shifts in dominant species. Despite apparent compositional similarity between 2017 and 2024, there was an increase in obligate wetland species in the groundcover layer, and an overall trend towards wetter conditions as assessed through species wetness coefficients. These results reflect the impacts of black ash loss in non-ash-dominated forests, where co-occurring canopy species may mitigate major compositional change that may otherwise occur in more significant canopy dieback events. Further long-term monitoring is required to evaluate any intensifying hydrological changes and the ability of functional replacements of black ash to tolerate shifts in community structure.
Practical challenges when updating tree marking direction to prioritize crown dieback
(2024-01) Adair, Hannah; Caspersen, John
In Ontario’s Great Lakes – St. Lawrence Forest region, professional tree markers are often relied upon to select trees for harvest, based on the presence or absence of various defects. Conventional tree marking guidelines do not currently make any distinction between defects which affect tree vigour, and those that affect tree quality. It is desirable to retain trees that are high vigour, and therefore likely to continue to provide seed and ecosystem services to the residual stand for at least another 20 years, while harvesting enough high-quality timber to make these stand improvement cuts economically viable. For this reason, it is important that the distinction between vigour and quality be taken into consideration in tree marking prescriptions. Defects which have been shown to indicate that a tree is low vigour include crown dieback (CDBK), fungi, and cankers. Defects which indicate that a tree is low quality include fungi, cankers, cracks, cavities, and decay. CDBK is one of the most useful indicators that a tree is lower vigour when affecting at least 15% of the crown. This indicator could be given considerably more importance when tree marking. There is currently no official threshold used in Ontario, but CDBK will usually only be considered as a defect if it is affecting at least 50% of a tree’s canopy. The purpose of this study was to test out a proposed, simplified tree marking system which reflects these advances in our understanding of defects as indicators of vigour and quality and prioritizes the removal of low vigour/high quality trees (with ≥ 15% CDBK but no quality affecting defects). We compared this new prescription with two conventional prescriptions by having experienced tree markers use all three in eight different plots. We were expecting the new prescription to result in 1) improved residual stand vigour (because it prioritizes the removal of trees with CDBK) and 2) increased consistency between tree markers (because the defect list they were using was shorter than that of the conventional systems). Neither of these desired outcomes were achieved in practice – we observed no significant difference in CDBK marked or consistency between the three prescriptions. This study represents an important first try at updating tree marking direction. Subsequent trials will be necessary to refine the new prescription, to achieve desired management outcomes in the field.
Regeneration response of tolerant hardwoods to beech bark disease vegetation management
(2024-01) Bein, Aliya; Caspersen, John
Beech bark disease (BBD) is the most significant natural disturbance affecting the Bancroft Minden Forest (BMF) and other forests across central Ontario. As a response to mortality from BBD or root injuries from harvesting, beech trees regenerate at a quicker rate than other species as they are very shade tolerant and can reproduce asexually from root or stump sprouts or sexually from a parent tree. The dominant regeneration of beech will affect the future composition of the forest as it makes it difficult for more valuable species to regenerate. Several vegetation management treatments are available to remove understory regeneration and mitigate root sprouts, such as mechanical treatments and chemical treatments. This study aims to determine which vegetation management treatment, between a mechanical brush saw treatment and a basal bark application of the herbicide triclopyr, is more effective six years after treatments were applied. Our results show that six years after treatments were applied, there is no significant difference between the two treatments amongst the large beech regeneration. However, the basal bark application of triclopyr may be a more effective long term treatment than the brush saw when looking at the small and medium regeneration size classes likely due to the increased sprouting response after mechanical treatments. We also aim to determine if these treatments had an effect on the regeneration of more desirable species such as sugar maple. We found no evidence that the treatments had any effect on sugar maple regeneration.
Ash Tree Regeneration & Decline in Lake Simcoe Watershed
(2024-01-12) Newell, Jack; Puric-Mladenovic, Danijela
The invasive emerald ash borer (Agrilus planipennis) is currently a major threat to ash trees throughout southern Ontario. We examined 20 plots in the Lake Simcoe Watershed in the years 2017 and 2023 to determine the effect that EAB had on the regeneration of the three major ash species in the region: white (Fraxinus americana), black (Fraxinus nigra), and red ash (Fraxinus pennsylvanica). Analysis was conducted to determine if there were declines in any of the canopy, sub-canopy, shrub layer, ground layer, and basal area of ash trees over the period of six years. Significant decreases were found in both the canopy and basal area but not in the sub-canopy, shrub layer, or ground layer. EAB was found to be having a significant negative effect on only the most mature trees. However, the lower levels were found to have remained the same, indicating that seed production from the top layer has not been significantly hindered by EAB infestation.
Urban Forestry and Energy Efficiency: A Case Study in Waterloo's Public Schools
(2024-01-10) Zhao, Yifeng; Puric-Mladenovic, Danijela
This capstone project delves into the intricate relationship between tree species, their canopy cover, and their impact on energy consumption within school buildings. Through an analysis of tree data surrounding school buildings, we quantified the average canopy cover for each school. Tree canopy covers by schools range from a sparse 5% to a lush 27.3%. Similarly, school buildings overlapped by tree canopy also vary. This study also examines the spatial arrangement of trees near buildings and elucidates how different tree species and their canopies influence school energy saving. It highlights how tree shading can affect carbon emissions and energy consumption for heating and cooling, thus underpinning the pivotal role of urban trees in enhancing energy efficiency in educational environments. In addition, a rational management strategy is given that serves as a cornerstone for future research to optimize green space management and urban planning, specifically tailored to bolster school energy conservation.
Physical Accessibility of Cedar for Cultural Use in Haida Gwaii Cedar Stewardship Areas
(2024-01-08) Jackson, Carly; Koven, Anne; Puric-Mladenovic, Danijela
Often referred to as the edge of the world, Haida Gwaii is an island archipelago off the northwest coast of British Columbia. Home to the Haida peoples for thousands of years, its forests are dominated by western hemlock, Sitka spruce, western red cedar, yellow cedar, and red alder. Cedar is the newest arrival on the islands, showing up around 1230 BC, however, due to its rot-resistant properties, it was adapted into all aspects of Haida life, from cradle to grave. Cedar became central to Haida culture, making red and yellow cedar important to protect to ensure future generations of Haida have access to the wood as well. Logging became widespread across the islands a few decades after the turn of the century because the large trees of the temperate rainforest region were prized for building materials. After decades of logging, particularly old growth trees, members of the Haida Nation brought forward a mandate in 1993 and again in 2001 over concern about the over-logging of cedar trees, fearing the loss of cultural sustainability. In response to this, Cedar Stewardship Areas (CSAs) were created with the intention of preserving cedar, and a management plan for the areas was published in 2016. This study uses the 2016 management plan as a foundation and builds on it by revisiting the CSAs and analyzing their physical accessibility for members of the Haida Nation. This is done by spatially assessing three factors; species dominance to determine cedar dominant stands within CSAs, road access and walkability from the roads, and terrain. Overall accessibility was determined by applying an accessibility rating system to the CSAs and comparing the outcome to the results from the spatial analysis. Results reveal that less than 50% of the CSAs are cedar dominant stands, not all the areas within the CSAs are reachable by road or foot based on the criteria set forth in this study, and steep slopes in certain CSAs add to difficult access. The study recommends collaborative planning between the Haida Nation, CHN, government of BC, and local logging licensees to devise permanent routes into CSAs that will be maintained by central funding. Additionally, future ethnographical research about the importance of CSAs coupled with scientific research involving CSAs could be conducted to raise more awareness and strengthen the protection of the areas. This study aims to bridge the gap between policy and reality in terms of cultural wood access in Cedar Stewardship Areas.
Ecological Restoration on Municipal Public Parklands: Assessing LEAF’s Community Tree Planting in York Region
(2023-12-19) IDOWU, Dele Solomon; SMITH, Sandy M.
ABSTRACT: Ecological restoration, mainly through naturalization, is an effective method for transitioning damaged or degraded urban environments to a more natural state. LEAF, a non-profit organization, has played a pivotal role in urban forestry by engaging communities in tree-planting events since 2014. The organization emphasizes the importance of planting native species and addresses factors such as soil limitations, topography, and seedling characteristics. Naturalization efforts are costly, time-demanding to establish a tree, and expensive to implement and maintain. Hence, assessing the success of ecological restoration projects is critical to justify restoration in naturalization and improve best practices. This paper aims to assess LEAF’s Community Tree Planting approach to naturalization in the York Region, assess the practices and relative success of the LEAF-CTP program based on a review of tree survival between the years 2020 and 2022, and identify areas where tree planting improvement in the region and provide guidelines for LEAF’s future naturalized restoration projects. Adopted for this study were a multi-stage sampling procedure with a three-stage design. LEAF provided information on Community Tree Planting (CTP) areas and planting practices and prepared survival assessment data for the areas covered each year for analysis. The data obtained were analyzed using both one-way ANOVA and descriptive statistical techniques. The survival rate, diversity index, and health status were analyzed, and invasive species were identified and documented. The ANOVA results reveal that sapling height significantly affected plant survival while other factors did not. The results showed records of 94% survival rates out of 5,421 trees and shrubs planted between 2020 and 2022, with a 0.9 diversity index. A minimum survival rate of 66% was recorded at Humber Flats Ecopark of Richmond Hill in 2020, with poor health status recorded in three public parklands out of eight parklands with trees and shrubs. Identified with invasive species are 26% of the total plots established in the study area. The study concluded that LEAF-CTP’s approach to naturalization across the York Region is advancing with a high diversity of woody plants across the years in all the cities. According to LEAF practises, all plots were mulched, but not all plots were watered, identified fewer invasive species in Richmond Hill and none at King and Markham City. Hence, this study recommends continuing planting events with community participation and adequate monitoring. Experimental trees and shrub planting design will be better than on a plot basis. Smaller (lower height) saplings should be used for planting as they can withstand environmental stress. Ensuring proper watering to promote root growth in the topsoil as part of a new tree-planting technique and managing invasive species to ensure better-established planted trees is vital.
Stand level forest management for biodiversity and Ecosystem Based Management on Haida Gwaii/Queen Charlotte Islands
(2006) Toledo, Ricardo; Caspersen, John
Ecosystem-Based Management (EBM) is gaining increasing legitimacy in the province of British Columbia as an integrated planning and operational framework that ensures social, economic, and ecological goals are achieved from activities in the forested landscape. Industry has expressed worry that the added restrictions imposed by EBM will represent an insurmountable loss of profitability. This study involves the analysis of site plans and timber cruise data for 14 randomly selected cut blocks on Haida Gwaii/ Queen Charlotte Islands (HG/QCI) in order to determine whether current management practices for stand level biodiversity are consistent with the Ecosystem Based Management (EBM) benchmarks. The quantity and quality of wildlife tree retention was examined. Percentage of wildlife tree retention was calculated using site plan records for all areas harvested between January 2004 and July 2006. Structural attributes were measured for a sub-sample of 14 blocks and compared to pre-harvest timber cruise data. The study found that on HG/QCI average per cutblock wildlife tree retention, calculated as a proportion of TAUP, would need to increase by 79 percent in order to meet the minimum EBM benchmark. No significant deviation in the quality of structural attributes and species composition of this retention was found relative to the pre-harvest stand. Unless levels of wildlife tree retention can be increased substantially, ecosystem-based management on HG/QCI remains a distant goal.
Perspectives and Approaches to Sustainable Forest Management on the Queen Charlotte Islands/Haida Gwaii
(2005) Furrer, Martina; Blake, Terry; Kant, Shashi
The old growth hemlock and cedar forests on the Queen Charlotte Islands/Haida Gwaii are among the most biologically diverse temperate forests on Earth. They represent the largest intact temperate rainforests on Earth. Conflicts surrounding the use and management of forest resources on Haida Gwaii have received global attention. There have been many disagreements among the forest industry, the provincial government, the Haida Nation and local environmental groups with regard to forest management practices. There is much concern surrounding the current rate of harvest and the longterm supply of monumental sized red cedar (Thuja plicata). The objective of this paper is to look for similarities among the often contrasting perspectives and approaches to sustainable forest management of the forest industry, the BC government, the Haida Nation and several local environmental groups. A questionnaire was designed to assess different parties' understandings of and commitments to sustainable forest management. One representative from each of 11 organizations involved in forest management on Haida Gwaii was interviewed. With respect to their perspectives on sustainable forest management, all respondents agreed that sustainable forest management involves balancing ecological, economic and social components. They also agreed that sustainable forest management involves managing the resource such that today's needs are met without compromising the resource for future generations. The forest industry, the government, the Haida and the environmental groups agreed that cooperative work is a necessary precursor for sustainable forest management. The conservation and management of red cedar is important to the Haida and environmental groups, and to a lesser extent government and industry. This research shows the four groups share similar perspectives and approaches to sustainable forest management. They are not as far apart as it often seems on the surface. Acknowledging one another's positions and recognizing commonalities may be an important first step in improving forest management strategies and practices on the Queen Charlotte Islands/Haida Gwaii.
Monitoring the effects of deer on plant abundance and diversity in old-growth temperate coastal rainforests, Haida Gwaii, British Columbia
(2009) McKenzie, Annie; Kenney, Andy
Overabundant deer populations are a major factor affecting forest ecosystem dynamics in many parts of North America. Sitka black-tailed deer (Odocoileus hemionus sitkensis) were introduced to Haida Gwaii, a remote island archipelago in British Columbia, in the late 19th century. The mild climate, abundant vegetation, absence of predators, low hunting pressure and lack of competing herbivores on Haida Gwaii allowed the deer to flourish and the population exploded. This long-term monitoring experiment studies the. effects of Sitka black-tailed deer on the diversity, abundance and reproduction of understory vegetation. In this study 20 deer exclosures were monitored over a period of 12 years from 1997 to 2009 in old growth forests on Graham Island, the largest island of the Haida Gwaii archipelago. The results showed that protection from deer did not have an effect on species richness. However, deer are having a significant impact on the abundance of understory vegetation in the medium height stratum (0.5 m - 1.5 m) and they are shifting the community composition towards less palatable species. The plant species most affected by deer browsing were bunchberry (Cornus unalaschkensis) and fern-leaved goldthread (Coptis aspleniifolia), and these are important forage species for Sitka black-tailed deer in their natural habitat in Alaska. Deer are also having an impact on plant reproduction, as a significantly higher proportion of flowers and fruits were found inside the exclosures. More research is needed to understand the impacts of deer on understory vegetation and therefore this study provides practical recommendations for improving this long-term monitoring experiment as well as recommendations for future research.
Stumping Deer: Are Old Growth Stumps Creating Refugia for Understory Plants on Haida Gwaii?
(2010) Holmes, Dan; Caspersen, John; Kenney, Andy
Sitka black-tailed deer (Odocoileus hemionus sitchensis) were introduced to Haida Gwaii, British Columbia in the late 19th century and are having a dramatic impact on the regeneration of understory vegetation. Although never formally tested, past investigations have reported that in parts of Haida Gwaii understory vegetation is restricted to old growth stumps, suggesting they are providing refugia from browsing deer. Additionally, little is known about which plant species utilize stumps and whether these communities' changes during stand development. The objectives of this study is to (1) determine if old growth stumps are providing refugia for understory plants and (2) determine if stand age influences the understory plant community. Species density(# of species/m2) and percent cover of vegetation present on stumps above (>1.5 m) and below (<1.5 m) the deer browse line as well on the forest floor was assessed across sitka spruce (Picea sitchensis) dominated stands of different ages: 10 years after clear cut harvesting, 30 years after clear cut harvesting, 60 years after clear cut harvesting and old growth (>250 years). Species density and percent cover was found to be greatest on the forest floor in the 10 and 30 year old stands, indicating that stumps are providing relatively poor refugia in younger stands. The only indication that stumps provided protection for understory plants was found in the 60 and >250 year old stands. In these stands percent cover was significantly greater on stumps above the browse line than on stumps below the browse line or the forest floor. Possible reasons for why stumps in younger stands are not providing refugia for vegetation include substrate preference and microclimate. Many plant species prefer to germinate and establish on soil rather than woody material. Furthermore, stumps extending beyond the browse line likely experience more extreme high and low temperatures limiting plant establishment and growth. However, these factors likely diminish as the stand ages. Most plant species appeared not to have a clear association with a single stand age class. The exceptions to this include Gaultheria shallon which appears to prefer 30 year old stands and graminoids which showed the greatest species richness on the forest floor of the 10 year old stands. Overall, the results from this study suggest that the understory vegetation of older stands will benefit the most from stump refugia. Species with strong preferences for soil substrate will benefit the least.
An Assessment of Habitat Suitability in Old Growth and Secondary Growth Retention Area’s on Haida Gwaii
(2015) Hudson, Virginia; Malcolm, Jay; Munt, Leonard
In British Columbia, tree retention in harvested areas has become a standard forest management practice, however the ecological benefits that result from tree retention remain uncertain. Tree retention in the harvested landscape is thought to have the potential to ameliorate negative ecological effects of logging as it can provide refugia for elements of biological diversity, structural enrichment by retaining forest features, and enhance connectivity in the landscape between forested areas. Habitat quality in retention areas is important for avian species as it can influence suitable nest site structural features, predation levels, prey availability, competition rates, and nest-area microclimate. In the following study, old growth and second growth tree retention areas were analyzed on Haida Gwaii in order to examine structural habitat features. The structural features present in these retention types were then related to the published habitat characteristics of three old growth forest dependent avian species at risk on Haida Gwaii, in order to determine if suitable habitat is available in these retention areas. The three species analysed were the northern saw-whet brooksi owl (Aegolius acadicus brooksi), the marbled murrelet (Brachyramphus marmoratus), and the northern laingi goshawk (Accipiter gentilis /aingi). A total of 10 old growth and 11 second growth retention areas were surveyed in the Skidegate Plateau physiographic region of Haida Gwaii that were adjacent to cut blocks harvested within 3 years of 2015. The second growth retention areas surveyed in this study resulted from a harvest 50-65 years previously and most were mechanically thinned when 15-25 years old. Variable radius plots (prism sweeps) and snag and downed woody debris (DWD) transects were carried out in order examine structural features in retention stands. Vertical distribution of foliage was measured by estimating foliage percent cover in 6 height classes, while vertical canopy complexity was measured by estimating height differences between dominant and co-dominant canopy layers. Canopy gaps, salal (Gaultheria shallon) and Vaccinium (V. parvifolium, V. a/askaense, V. ovalifo/ium) abundances were estimated and dwarf mistletoe (Arceuthobium tsugense) and mossy platforms (> 18.5 cm dbh) were counted from plot centres. Old growth tree retention had significantly more diverse forest structure characteristics than second growth tree retention areas, however second growth tree retention areas contained some diverse features that most likely resulted from mechanical thinning. Results also indicated that old growth retention areas were significantly more suitable for all three avian species at risk with only a small proportion of the analyzed avian habitat characteristics present in second growth retention areas. Both retention types had edges exposed to harvested cut blocks, putting them at potential risk for forest edge related impacts, such as avian nest site predation and competition. My results indicate that second growth retention areas on Haida Gwaii lacked the structural complexity of old growth forests at age 50-65 years old. Strategies for improving habitats for old growth dependent avian species in such retention patches include: increased harvest rotation ages, strategic allocation in areas with large diameter trees and snags, and girdling or topping of suitable cavity nesting trees.

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