S. Ellen Macdonald

University of Alberta | UAlberta · Department of Renewable Resources

Many forested landscapes around the world are severely altered during mining for their rich mineral and energy reserves. Herein we provide an overview of the challenges inherent in efforts to restore mined landscapes to functioning forest ecosystems and present a synthesis of recent progress using examples from North America, Europe and Australia....

Although anthropogenic edges are an important consequence of timber harvesting, edges due to natural disturbances or landscape heterogeneity are also common. Forest edges have been well studied in temperate and tropical forests, but less so in less productive, disturbance‐adapted boreal forests. We synthesized data on forest vegetation at edges of...

Even though understory plant communities play important roles in northern forest ecosystems, our understanding of their long-term successional dynamics and the associated driving processes is still limited. This study used spatially explicit data from five, long-term, permanent plots in mature lodgepole pine (Pinus contorta) stands in the Canadian...

Industrial forestry typically leads to a simplified forest structure and altered species composition. Retention of trees at harvest was introduced about 25 years ago to mitigate negative impacts on biodiversity, mainly from clearcutting, and is now widely practiced in boreal and temperate regions. Despite numerous studies on response of flora and f...

The southern portions of the boreal region across Canada are dominated by boreal mixedwoods forests, which are characterized by varying canopy dominance of boreal broadleaf and conifer trees. This forest region encompasses a large east-to-west gradient of climate and disturbance regimes. Although the same major boreal tree species occur in all part...

Natural disturbance‐based management (NDBM) is hypothesized to maintain managed forest ecosystem integrity by reducing differences between natural and managed forests. The effectiveness of this approach often entails local comparisons of species composition or diversity for a variety of biota from managed and unmanaged forests. Understory vegetatio...

The most rapid climate warming is occurring in northern, permafrost environments. Peatlands of these regions are particularly sensitive to climate warming, with the high ground ice content of peat plateaux resulting in the formation of collapse scars as ground temperatures warm. To quantify the rates of permafrost thaw and associated vegetation cha...

In this chapter we summarize key features of aspen mixedwood stands, their development following disturbance and current silvicultural approaches. We then discuss ecological silvicultural systems aimed at maintaining varying mixtures in space and time, maintaining structural heterogeneity, and accepting variability and uncertainty. We focus on use...

We examined edge effects of narrow linear openings on the performance of cow-wheat (Melampyrum lineare, Desr.), an herbaceous annual and facultative hemi-parasite, in the boreal forest. Our objective was to determine the edge effects from linear disturbances: (1) on the abundance and performance (height, flower, and fruit production) of cow-wheat a...

The recent expansion of mountain pine beetle (MPB, Dendroctonus ponderosae) from its native range in western North America into northern boreal pine forests in Alberta, Canada has resulted in conditions for tree regeneration that are dramatically different from those after wildfire, the predominant natural disturbance in these forests. We assessed...

Many studies have focused on vegetation across forest edges to study impacts of edges created by human activities on forest structure and composition, or patterns of vegetation at inherent natural edges. Our objective was to create a database of plant‐related variables across different types of edges from various studies (mainly from across Canada,...

The boreal forest is a vast biome encompassing approximately one-third (30%) of the world’s forest area. It harbors about half of the world’s remaining natural and near-natural forests and provides important ecological, economic, social, and cultural services and values that benefit human communities (Burton et al., 2010; Gauthier et al., 2015a). A...

Retention harvesting is advocated as an alternative to intensive timber harvesting, such as clear‐cutting, to better maintain or facilitate recovery of biodiversity and other ecological values in managed forests. However, it is not clear how long the benefits of retention harvests persist. We investigated responses of understory vascular plant cove...

Oil sands mining in northeastern Alberta, Canada, generates tailings containing sand, silt, clay, water, and residual bitumen with hydrocarbons. The impact of tailings on revegetation is a major environmental concern and poses a significant land reclamation challenge. Oil sands companies have recently developed technologies that use thickeners in c...

Treed peatlands are dominated by bryophytes, particularly Sphagnum spp., which create the characteristic hummock‐hollow microtopography. This, in turn, shapes the distribution of bryophyte communities. Disturbances can lead to a loss of this microtopographic variation, impacting the bryophyte community. Seismic lines are deforested linear disturban...

As boreal forests rapidly warm due to anthropogenic climate change, long‐term baseline community data are needed to effectively characterize the corresponding ecological changes that are occurring in these forests. The combined seasonal dynamics (SEADYN) and annual dynamics (ANNDYN) data set, which documents the vegetative changes in boreal forests...

Climate warming in the North could lead to lichen decline within critical woodland caribou habitat. We used repeat measurements of sixty-nine plots over ten years (2007-2008 and 2017-2018) to assess lichen biomass changes under a warming climate along a latitudinal/climatic gradient in northwestern Canada. We compared lichen biomass on sensitive la...

Intraspecific trait variability (ITV) provides the material for species' adaptation to environmental changes. To advance our understanding of how ITV can contribute to species' adaptation to a wide range of environmental conditions, we studied five widespread understorey forest species exposed to both continental‐scale climate gradients, and local...

Questions Edge influence on forest biodiversity is an important environmental effect associated with habitat fragmentation, but extrapolating the influence of edges across the broader landscape has been difficult, especially for situations where multiple edges exist in close proximity. We asked whether there were differences in edge effects between...

For thousands of years Ɂedacho Kué (Artillery Lake, Northwest Territories) has been a key water crossing site for barren-ground caribou (Rangifer tarandus groenlandicus). Human disturbance of barren-ground caribou habitat in northern Canada has emerged as an important focus of study in the last decade; particularly in the Bathurst range of the Nort...

Global forest area is declining rapidly, along with degradation of the ecological condition of remaining forests. Hence it is necessary to adopt forest management approaches that can achieve a balance between (1) human management designs based on homogenization of forest structure to efficiently deliver economic values and (2) naturally emerging se...

Retention forestry is an approach in which live trees and other components of forest structure are retained within harvested areas. A primary objective of retention forestry is to maintain biodiversity and to hasten post-harvest recovery of forest structure and function. Retention is now a key element in sustainable forest management practices in m...

To inform biodiversity conservation efforts in managed forest landscapes, we explore if a topographic moisture index (depth-to-water, based on remotely-sensed (LIDAR) data) can provide insight into responses of understory vegetation to retention harvesting in the boreal mixedwood forests of northwestern Alberta, Canada. Sample plots were placed alo...

Disturbances are an integral part of forest ecosystems and drive successional change. The boreal forest is adapted to stand-replacing fires, which have different ecological impacts than less severe disturbances, such as insect attacks. In recent years, mountain pine beetle (MPB), a bark beetle native to western North America, has undergone an unpre...

Forests are increasingly affected by natural disturbances. Subsequent salvage logging, a widespread management practice conducted predominantly to recover economic capital, produces further disturbance and impacts biodiversity worldwide. Hence, naturally disturbed forests are among the most threatened habitats in the world, with consequences for th...

Forests are increasingly affected by natural disturbances. Subsequent salvage logging, a widespread management practice conducted predominantly to recover economic capital, produces further disturbance and impacts biodiversity worldwide. Hence, naturally disturbed forests are among the most threatened habitats in the world, with consequences for th...

The construction of pipeline rights-of-way (ROWs, hereafter ‘pipeline’) involves mechanical site clearing, which impacts soil and ground cover vegetation and has implications for forage availability and predation risk for threatened wildlife, including woodland caribou (Rangifer tarandus) and grizzly bear (Ursus arctos). However, there has been no...

In peatlands, microtopography strongly affects understory plant communities. Disturbance can result in a loss of microtopographic variation, primarily through the loss of hummocks. To address this, mounding treatments can be used to restore microtopography. We examined the effects of mounding on the understory vegetation on seismic lines in wooded...

Storing a significant portion of the global carbon (C) stocks, soils of the boreal forest display a high degree of spatial heterogeneity across the landscape, arising from variation in forest structure and landscape morphology, as well as natural and anthropogenic disturbances. Because of this high degree of variability, accurately quantifying C st...

Regionally fitted allometric equations for individual trees and root-to-shoot ratio values are normally used to estimate local aboveground and belowground forest biomass, respectively. However, uncertainties arising from such applications are poorly understood. We developed equations for both aboveground and belowground biomass using destructive sa...

Responses, outcomes, and management options for lodgepole pine forests in Alberta following attack by Mountain Pine Beetle

For the purpose of informing biodiversity conservation efforts in managed landscapes, we explored whether and how understory plant communities (abundance, diversity, composition) were related to a topographic moisture index, called depth-to-water, in the boreal mixedwood forests of northwestern Alberta. Depth-to-water is an index of relative site m...

Atmospheric acid deposition is of major concern in the Athabasca Oil Sands Region (AOSR) in northern Alberta, Canada, which is home to the third largest oil reserve in the world. After decades of oil sands production in the AOSR, the potential impact of deposition on forest health, including tree growth and understory biodiversity, is still not cle...

Considering intraspecific trait variability (ITV) in ecological studies has improved our understanding of species persistence and coexistence. These advances are based on the growing number of leaf ITV studies over local gradients, but logistical constraints have prevented a solid examination of ITV in root traits or at scales reflecting species’ g...

We used repeat oblique photography to quantify and determine the drivers of vegetation change, particularly forest closure and encroachment, in the Rocky Mountains of southern Alberta, Canada from the beginning of the 20 th century to the present. We classified the landscape into seven distinct vegetation types (closed canopy conifer-, broadleaf de...

Wildfire is the predominant natural disturbance in the boreal forests of western Canada. Natural disturbance based forest management involves the use of retention harvesting to retain stand structural diversity after harvest; however, unlike fire, this partial harvesting technique does not cause combustion of the forest floor. Application of prescr...

Dead wood (DW) provides critical habitat for thousands of species in forests, but its amount, quality and diversity have been heavily reduced by forestry. Therefore, interventions aiming to increase DW might be necessary to support its associated biodiversity, even in protected forests, which may be former production forests. Our aim was to synthes...

Retention harvesting, or the approach of leaving live mature trees behind during forest harvest, is used in natural disturbance‐based management to mitigate the effects of logging on biodiversity. However, responses of many boreal vertebrates to variable retention harvesting are unknown. We investigated the influence of different retention levels i...

Site moisture is an important component of the forest landscape for maintaining biodiversity, including forest‐floor bryophytes. However, little is known about its role in shaping understorey responses to harvesting. We investigated the influence of site wetness, determined using a remotely sensed, topographic depth‐to‐water (DTW) index, on respons...

Montane regions throughout western North America have experienced increases in forest canopy closure and forest encroachment into grasslands over the past century; this has been attributed to climate change and fire suppression/exclusion. These changes threaten ecological values and potentially increase probabilities of intense wildfire. Restoratio...

Given projected rates of climate change, species with limited dispersal may be unable to migrate at the pace necessary to maintain their current climate niches. This could lead to increased risk of extirpation or extinction, especially for locally range-restricted species within fragmented landscapes. Assisted migration has been suggested as a proa...

The spatial effects of vegetation control on early tree growth were investigated in central Alberta, Canada, for four years after the establishment of hybrid poplar plantations including the two clones Walker (Populus deltoides × (P. laurifolia × P. nigra)) and its progeny Okanese (Walker × (P.laurifolia × P. nigra)). Tree survival and growth, herb...

Background Livestock grazing and ‘overabundance’ of large wild herbivores in forested areas have long been perceived as conflicting with the aims of both silviculture and forest conservation; however, certain kinds of herbivory can help to maintain habitat values in forest ecosystems. Management of mammalian herbivory in protected forests can, ther...

Retention harvesting (also called tree retention or structural retention), in which live mature trees are selectively retained within harvested stands at different retention levels and in different patterns (aggregated to dispersed), is increasingly being used to mitigate the negative impacts of forest harvesting on biodiversity. However, the effec...

Given the habitat moisture (air humidity or soil moisture) preferences of many forest bryophytes, we explored whether the depth-to-water (DTW) index, derived from remotely sensed Light Detection and Ranging (LiDAR) data, was related to fine-scale patterns of spatial variation in bryophyte abundance, diversity, and composition. The goal was to asses...

Wildfires, insect outbreaks, and windstorms are increasingly common forest disturbances. Post-disturbance management often involves salvage logging, i.e., the felling and removal of the affected trees; however, this practice may represent an additional disturbance with effects on ecosystem processes and services. We developed a systematic map to pr...

Imperfect detection leads to underestimates of species presence and decreases the reliability of survey data. Imperfect detection has not been examined in detail for boreal forest understory plants, despite widespread use of surveys for rare plants prior to development. We addressed this issue using detectability trials conducted in Alberta, Canada...

Question What are the processes driving regeneration and successional pathways in Pinus contorta subsp. latifolia Douglas ex Loudon forests? Location Canadian Rockies, Alberta, Canada. Methods We used five 1‐ha long‐term permanent plots, dendrochronological stand reconstruction and detailed spatial analysis of stem‐mapped data. Results Establish...

Given a seed source, the quality of available substrates is a key factor in determining the success of white spruce (Picea glauca (Moench) Voss) natural regeneration. We examined the influence of substrate and competing vegetation on survival and growth of natural regeneration of white spruce up to 4 years following harvesting in deciduous-dominate...

Aims Reclamation following oil sands mining in northeastern Alberta (Canada) creates adverse reforestation soil conditions, including extreme pH values. We elucidated pH tolerance limits of boreal plant species and how pH affects nutrient uptake in these plants. Methods We measured growth, gas exchange, and foliar nutrient concentration of 15 comm...

The effects of different understorey management practices on tree-weed dynamics and associated tree establishment were investigated in newly planted hybrid poplar plantations containing Walker poplar (Populus deltoides × (P. laurifolia × P. nigra)) and its progeny Okanese poplar (Walker × (P. laurifolia × P. nigra)). Trees were established in 2012...

Variable‐retention harvest is widely recognized as an alternative to more intensive methods such as clear‐cutting. However, present information is inadequate to judge the impact of variable retention on biodiversity of indigenous forest organisms intolerant of canopy removal, such as forest‐inhabiting bryophytes. We examined how bryophyte species c...

The extent to which past states influence present and future ecosystem characteristics (ecosystem memory (EM)) is challenging to assess because signals of past ecological conditions fade with time. Using data about seven different taxa, we show that ecological gradients initiated by wildfires up to three centuries earlier affect biotic recovery aft...

Background Livestock grazing and ‘overabundance’ of large wild herbivores in forested areas have long been perceived as conflicting with the aims of both silviculture and forest conservation; however, certain kinds of herbivory can help to maintain habitat values in forest ecosystems. Management of grazing/browsing in protected forests can, therefo...

The effect of varying composition and abundance of neighbouring herbaceous vegetation on tree growth in commercial hybrid poplar plantations remains unclear. We evaluated relationships between tree stem volume, volume increment, and the abundance of various growth forms (perennial grasses, legumes, and perennial forbs excluding legumes) adjacent to...