Ecosystems of British Columbia

Coastal moderation of Holocene fire and vegetation change on the Pacific coast of Canada

Article

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Feb 2025

In the coming century, climate variability is projected to increase in Northeast Pacific coastal areas, increasing the need for land managers to understand how ecosystems are expected to change in response to new or enhanced disturbances. Previous research indicates that the Pacific coast of Canada, southern British Columbia (BC) experienced warmer and drier climate conditions than present, with higher than modern fire activity during the early Holocene xerothermic interval (9.5 – 7.0 kcal BP). In this study, we reconstructed past climate-fire-vegetation changes from a 13,000-year sediment record from Lost Lake in Vancouver’s Lower Seymour Conservation Reserve, BC. Contrary to other sites, the coastal western hemlock forest at this site remained cool and moist with low fire activity throughout the xerothermic period. Instead, peak fire frequencies were observed during the cool and moist Neoglacial period (4.5 kcal BP – present), when human activity became prevalent. These results have implications for the managed watershed’s resilience to fire and response to future warming conditions.

Climate, wildfire, and volcanic ash drivers of ecosystem change in high mountain forests, British Columbia, Canada

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May 2024

Northwest North America has unique high elevation Picea–Abies forests and parkland classified in British Columbia as the Engelmann Spruce–Subalpine–fir (ESSF) Biogeoclimatic zone. These ecosystems occur on a topographically and climatically complex landscape, juxtaposed with diverse vegetation types including alpine tundra, inland rain forest, dry conifer forest, and grasslands. Spatio-temporal ecosystem disturbance is varied, driven by factors such as climate variation, wildfire, volcanic eruptions, and insect herbivory. A pollen and charcoal record derived from a lake sediment core from the ESSF reveals a unique late-glacial to modern vegetation history progressing from alpine steppe through dry open conifer forest to moist spruce–fir ecosystems, the latter arising only 4600 years ago, late by comparison to other ESSF sites in the region. Repeated disturbance in the mid Holocene by wildfire coupled with volcanic ash deposition and increased climatic variation resulted in recurring Pinus contorta-dominated seral forest stands before cooling and moistening in the late Holocene led to stable Picea–Abies forest. With rapid climate change, changing disturbance regimes, and timber harvest, the management of dry ESSF forests needs to consider that this forest-type could transform into parkland or open seral pine stands, with a high frequency disturbance regime.

Using winter diet composition and forage plant availability to determine browse selection and importance for moose ( Alces alces ) in a landscape modified by industrial forestry

Article

May 2024

Between 2000 and 2015, moose (Alces alces L.) populations within some areas of north-central British Columbia, Canada declined by 70%. Such declines are occurring in other regions within the range of moose. One cause for mortalities of cow and calf moose in British Columbia was apparent starvation, implying a potential connection to food supply. To investigate possible connections between moose declines and industrial forestry, we examined moose winter diets relative to browse availability in six Biogeoclimatic Ecosystem Classification subzones within north-central British Columbia. In the spring of 2017, we collected moose winter pellets. To assess diet, pellets were analyzed using microhistology, a common technique for quantifying the diets of ungulates. In the summer of 2018, we used a modified point-intercept method to survey browse plant availability at pellet collection sites. We related diet composition to plant availability through indices of selection (use of a forage species relative to availability) and values of importance (the proportion of a species in the diet as a function of its occurrence in the environment) of various browse items to moose. Twenty-eight species of potential browse plants were identified in our browse availability surveys. Only 12 of these plants were found in moose pellets, with four plants [subalpine fir (Abies lasiocarpa Hooker), willow (Salix spp. Linnaeus), paper birch (Betula papyrifera Marshall), and trembling aspen (Populus tremuloides Michaux)] comprising the majority (93.3%) of the diet. We used mixed-model analyses to examine differences between these top four winter diet items, in relation to: (i) diet composition; (ii) plant availability; (iii) selection by moose; and (iv) importance to moose. Subalpine fir (mean: 45.7%) was a significantly larger diet component in pellets than aspen (5.7%) and willow (19.5%), but there was no significant difference in the proportions of subalpine fir and birch (22.4%). Birch and willow were found in significantly higher proportions than aspen, but proportions of birch and willow in pellets did not differ. The availability of the top four diet items was not significantly different between species. Subalpine fir, aspen, birch, and willow were the most selected diet items, but selection was not significantly different between them. The importance values of subalpine fir, birch, and willow were not significantly different from one another, but all three were significantly greater than the importance value for aspen. Diet composition, availability, selection, and importance did not vary between subzones surveyed. The high selection for and importance of subalpine fir, birch, willow, and aspen by moose in winter demonstrate the need to ensure these browse species are maintained on moose ranges, especially where moose populations are declining. Where industrial forestry impacts the abundance and species composition of winter browses for moose, we encourage forest planners and managers to examine browse availability in relation to moose diet, so that the browse plants important to and selected for by moose can be integrated into forest management objectives.

Thirty-year responses of ecosystem components to stand thinning in lodgepole pine forest: Old-forest attributes, stand structure, and forest-floor small mammals

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May 2025
FOREST ECOL MANAG

Biomass production via higher yields of wood fibre in boreal and temperate forests may be enhanced by silvi-cultural treatments such as stand thinning. Restoration of old-forest structural attributes in second-growth forests is also much needed for conservation of wildlife species and biodiversity. We ask if pre-commercial thinning over a wide range of densities could enhance forest productivity while concurrently developing old-forest structures? We tested the hypotheses (H) that, compared with unmanaged (unthinned and old-growth) stands, large-scale pre-commercial thinning (heavy thinning to ≤ 500 trees/ha) over a 30-year period, would enhance (H 1) structural features (increase diameter and height growth and tree crown volume) of crop trees; (H 2) productivity based on merchantable volume and carbon storage of crop trees; (H 3) development of old-forest structural attributes ; and (H 4) total abundance, species richness, and species diversity of forest-floor small mammals. Four replicate blocks of pre-commercially thinned target densities of 250 (very low), 500 (low), 1000 (medium), and 2000 (high) trees/ha, unthinned, and old-growth stands of lodgepole pine (Pinus contorta var. latifolia) were located at three study areas in south-central British Columbia, Canada. Tree and stand measurements were conducted at 30 years post-thinning when stands were 43-47 years old. Small mammals were live-trapped in stands during 2023 and 2024. Mean diameter of crop trees followed the pattern of density with the highest growth in the very low-density stands and lowest in the unthinned stands. Mean tree heights were tallest in the old-growth stands and lowest in the unthinned stands. Very large tree crowns were evident in the three heavily thinned (≤ 1000 trees/ha) stands. These results partly supported H 1. Mean merchantable volume of pine crop trees was highest in the old-growth stands and secondarily in the unthinned and ≥ 1000 trees/ha thinned stands, and hence did not support this part of H 2. Mean carbon storage was similar among stands owing to the very large tree crowns in the heavily thinned stands and provided partial support for H 2. Owing to ingress, total crop tree densities were similar among the four thinned stand densities ranging from 1199 to 1479 trees/ha. Heavily thinned stands had some old forest attributes including large dominant trees with substantial crowns, multi-layered canopies of coniferous trees, canopy gaps, and understory patchiness, and hence supported H 3. Mean total abundance of small mammals was similar among stands in 2023 but higher in the very low-density, unthinned, and old-growth stands than other stands in 2024, and hence partly supported H 4. To our knowledge , this is the first detailed reporting of the 30-year responses of tree growth metrics and stand development in thinned stands of lodgepole pine at a real-world scale and across a wide range of densities. Much of the potential carbon storage lost by thinning was restored in the heavily thinned stands at 30 years post-thinning. Merchantable timber may be achieved in a considerably reduced rotation and may be a viable means to address current and future timber shortfalls. Restored forests, at 30 years after pre-commercial thinning, may be 40-50 years old and be at least partly comparable to uncut old-forest in some respects.

Mapping the Spatial Heterogeneity of Watershed Ecosystems and Water Quality in Rainforest Fjordlands

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Mar 2025
ECOSYSTEMS

Small coastal watersheds (< 10,000 km²) can play a large role in forming biogeochemical linkages between land and sea, yet the spatial heterogeneity of small watershed ecosystems is poorly understood due to sparse observations in many regions. In this study, we examined the spatial heterogeneity of water quality exported from diverse watersheds in two rainforest fjordland complexes. Samples were collected about monthly for a year from the outlets of 56 watersheds spanning from high mountains to low islands. Many (20) water quality properties varied significantly across six previously established watershed types defined by 12 easily computed geospatial variables. For example, organic matter concentrations ranged from very low in a Glacierized Mountains watershed type (1.2 ± 0.1 mg L⁻¹ DOC; 28.5 ± 4.6 µg L⁻¹ DON) to very high (15.1 ± 1.0 mg L⁻¹ DOC; 215.6 ± 20.4 µg L⁻¹ DON) in a Rain Lowlands type. Along this gradient, the dominant form of dissolved nitrogen switched from inorganic to organic and the dominant form of phosphorous switched from particulate to dissolved. Watershed type alone explained 67% of the variance in the first principal component of water quality (PC1) representing 20 water properties. Although underlying causes were likely complex, a great deal of spatial variation in water quality (for example, 91% of PC1) was predicted by simple measures of topography and climate (for example, elevation and mean annual precipitation). The physiographic structure of the coastal land mass appears to enable a complex mosaic of watershed ecosystems, which may affect meta-ecosystem function at the coastal margin.

Forestry, fire, and fur: factors influencing densities of endangered fishers ( Pekania pennanti ) in central British Columbia, Canada

Article

Mar 2025
J WILDLIFE MANAGE

The isolated and endangered Columbian population of fishers ( Pekania pennanti ) is thought to be declining in central interior British Columbia, Canada, yet little is known about the distribution and abundance of the species in several regions. We conducted DNA‐based mark‐recapture surveys to estimate the density of fishers in 2 spatially distinct ecosystems where current data were lacking, and evaluated which factors best explained the distribution of fishers in each ecosystem. We found the density of fishers varied substantially between study areas, likely because of the level of trapping mortality during each survey season. The density of fishers in the Chilcotin study area west of Williams Lake was among the highest ever reported for the province (21.3 ± 3.8 [SE] fishers/1,000 km ² ), whereas density in the Enterprise study area southeast of Williams Lake was among the lowest (8.9 ± 2.7 fishers/1,000 km ² ). Density estimates for both study areas, however, were orders of magnitude lower than those reported for eastern North America and the western United States and thus are at levels worthy of concern. Forested stands with wet soil moisture regimes composed of older deciduous and spruce trees were most strongly related to higher densities in both study areas; these stands also were known to contain higher densities of the denning and resting structures fishers require to survive and reproduce. This study provided wildlife managers with a snapshot of the density of fishers in 2 areas of central interior British Columbia that will help refine the estimate for the endangered Columbian population. Additionally, this work suggests that reducing trapping mortality within the Columbian population of fishers and increasing the protection of high‐value denning and resting habitats may both be necessary to promote the recovery of the species over the longer term.

Contrasting Effects of Broadleaf Thinning Treatments on Spruce Growth in Central British Columbia, Canada

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Dec 2024

As forest managers increasingly seek to develop and maintain mixedwood forests, more information is required on the potential facilitative and competitive interactions between tree species. We present data from a broadleaf thinning study established in a mixedwood stand in Central British Columbia, Canada, to examine how residual trembling aspen and paper birch competitively affect spruce growth after thinning but may also concurrently protect spruce from attack by the white pine weevil. Tree-level data collected at a stand age of 36 years, 19 years after broadleaf trees were thinned, show that spruce height and diameter growth declined with broadleaf competition, particularly from taller trees, resulting in a competition-related reduction in stand-level spruce volume yields. The fastest spruce growth occurred in treatments where all broadleaf trees were removed, but complete broadleaf removal also resulted in higher rates of weevil attack on spruce, which also caused height and diameter growth reductions. Our results suggest that maintaining a density of approximately 500 broadleaf trees per hectare may achieve a stand condition that balances spruce growth reductions from competitive interactions with broadleaf trees while providing some protection from white pine weevil attacks.

Inonotus tomentosus and the dynamics of unmanaged and partial-cut wet sub-boreal sprucefir forests

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Full-text available

Jan 2008

For wet sub-boreal sprucefir forests (white spruce (Picea glauca (Moench) Voss) Engelmann spruce (Picea engelmannii Parry ex Engelm.) subalpine fir (Abies lasiocarpa (Hook.) Nutt.)) in east-central British Columbia, we asked (i) do compositional and structural dynamics differ for unmanaged (UN) and partial-cut (PC) (50% removal 45years before measurement) forests and (ii) how does Inonotus tomentosus Fr. (Teng) affect these dynamics? Inonotus tomentosus infected stands had 17% less spruce basal area (P = 0.059) than uninfected stands, but PC did not exacerbate I. tomentosus effects. PC and UN had similar live tree density, but UN had lower dead tree density. In all stands, snag longevity was typically<32years, and ~40years was required for dead wood to reach decay stage 3 or greater. UN was characterized by variable severity disturbances averaging ~8% of the canopy per decade. Management implications include the following: (i) harvest systems designed to emulate small-scale disturbance could remove trees at 8% of the canopy per decade, varied spatiotemporally, (ii) emulating dead wood abundance with partial cutting may be difficult given the impacts of partial cutting on dead wood abundance, and (iii) forests with moderate levels of I. tomentosus should not respond differently to harvesting than uninfected forests and thus require no special management.

Vegetation quality assessment: A sampling-based loss-gain accounting framework for native, disturbed and reclaimed vegetation

Article

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Jan 2024
ECOL INDIC

Evaluating Coastal Douglas Fir Growth Responses to Nitrogen Application Using Tree Ring Chronologies

Article

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Dec 2023

Dendrochronology is a technique that can be applied as a retrospective monitoring (RM) approach to evaluate the performance of nutrient application in forest ecosystems. Applying the RM approach across operations lacks experimental controls, which may adversely affect accuracy and precision of estimates due to greater mismatches in stand conditions between treated and untreated plots. To test the rigor of the RM approach, we collected increment cores of coastal Douglas fir (Pseudotsuga menziesii var. menziesii) at eight sites of an experiment where stands were fertilized in 1971. First, we tested the approach under ideal conditions by sampling from treated and untreated plots of the experiment. Second, we tested the approach using newly established surrogate control (SC) plots, which differed in ecological site classification from those of the treated plots to understand how robust the approach was to mismatches in conditions between treated and untreated samples. We hypothesized that detrending ring width would mitigate error in responses to nutrient application resulting from mismatches in site classification. Within the experiment, the approach indicated an average increase of 15% (5% to 26%, p < 0.05) growth response to operational doses of urea. Different responses were found when the analysis relied on SC plots. Detrending low-frequency variation in ring widths eliminated differences in results arising, at least in part, to mismatches in site class. However, it also reduced the growth response using the experimental control plots to 10%. Dendrochronology with detrending shows promise in the ability to mitigate variation introduced by mismatches in ecological site classification that may occur in operational monitoring. Based on these results, we see potential to implement RM with operations to evaluate and optimize stand selection criteria.

Dietary niche overlap in an understudied Mustelidae community in the subboreal forests of western North America: does body size differentiate dietary niche?

Article

Nov 2023
COMMUNITY ECOL

Understanding the many ways closely related species are adapted to coexist is fundamental for maintaining biologically diverse ecological communities. We used carbon (C) and nitrogen (N) stable isotopes of hair and nail tissue to quantify overlap in dietary niche among American mink (Neogale vison von Schreber, 1776), American marten (Martes americana Turton, 1806), short-tailed weasel (Mustela erminea Linnaeus, 1758), and North American river otter (Lontra canadensis Schreber, 1777), and to quantify seasonal variation in diet among mink and marten. We collected tissue samples from the four species between 2015 and 2017 across an 18,000 km 2 area in central British Columbia, Canada. We hypothesised that the dietary niche breadth of the mustelid species would scale with body size. Standard ellipses suggested that mink had the broadest dietary niche and the only one that overlapped with all other species. Among marten, there was evidence of shifts in diet resulting from seasonal changes in the consumption of vertebrate prey. Marten and weasel occupied approximately the same isotopic space and their niches were contained fully within that of mink. Our results suggested that the coexistence of mink, marten, weasel, and river otter was driven in part by dietary niche partitioning. Differences in realized niche along spatial or temporal resource axes may have further contributed to preventing competitive exclusion among these closely related species. Although dietary analyses can provide insights on some components of interspecific competition, future investigations should include measures of spatial and temporal overlap in resource use.

Tree-CRowNN: A Network for Estimating Forest Stand Density from VHR Aerial Imagery

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Nov 2023

Estimating the number of trees within a forest stand, i.e., the forest stand density (FSD), is challenging at large scales. Recently, researchers have turned to a combination of remote sensing and machine learning techniques to derive these estimates. However, in most cases, the developed models rely heavily upon additional data such as LiDAR-based elevations or multispectral information and are mostly applied to managed environments rather than natural/mixed forests. Furthermore, they often require the time-consuming manual digitization or masking of target features, or an annotation using a bounding box rather than a simple point annotation. Here, we introduce the Tree Convolutional Row Neural Network (Tree-CRowNN), an alternative model for tree counting inspired by Multiple-Column Neural Network architecture to estimate the FSD over 12.8 m × 12.8 m plots from high-resolution RGB aerial imagery. Our model predicts the FSD with very high accuracy (MAE: ±2.1 stems/12.8 m2, RMSE: 3.0) over a range of forest conditions and shows promise in linking to Sentinel-2 imagery for broad-scale mapping (R2: 0.43, RMSE: 3.9 stems/12.8 m2). We believe that the satellite imagery linkage will be strengthened with future efforts, and transfer learning will enable the Tree-CRowNN model to predict the FSD accurately in other ecozones.

Woody debris structures on large clearcut openings: Oases for small mustelids and prey species?

Article

Sep 2023
FOREST ECOL MANAG

Can Moisture-Indicating Understory Plants Be Used to Predict Survivorship of Large Lodgepole Pine Trees During Severe Outbreaks of Mountain Pine Beetle?

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Full-text available

Jul 2023

Why do some mature lodgepole pines survive mountain pine beetle outbreaks while most are killed? Here we test the hypothesis that mature trees growing in sites with vascular plant indicators of high relative soil moisture are more likely to survive mountain pine beetle outbreaks than mature trees associated with indicators of lower relative soil moisture. Working in the Clearwater Valley of south central British Columbia, we inventoried understory plants growing near large-diameter and small-diameter survivors and nonsurvivors of a mountain pine beetle outbreak in the mid-2000s. When key understory species were ranked according to their accepted soil moisture indicator value, a significant positive correlation was found between survivorship in large-diameter pine and inferred relative high soil moisture status—a finding consistent with the well-documented importance of soil moisture in the mobilization of defense compounds in lodgepole pine. We suggest that indicators of soil moisture may be useful in predicting the survival of large pine trees in future pine beetle outbreaks. Study Implications: A recent outbreak of the mountain pine beetle resulted in unprecedented levels of lodgepole pine mortality across southern inland British Columbia. Here, we use moisture-dependent understory plants to show that large lodgepole pine trees growing in sites with high relative moisture are more likely than similar trees in drier sites to survive severe outbreaks of mountain pine beetle—a finding that may be related to a superior ability to mobilize chemical defense compounds compared with drought-stressed trees.

WOLF PREDATION ON MOOSE IN NORTH-CENTRAL BRITISH COLUMBIA

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Dec 2024

Moose populations declined substantially following widespread salvage logging of mountain pine beetle affected forests in interior British Columbia (B.C.) in the 2000s. The impact of wolf predation on moose was not well-understood in the context of extensive landscape change. We monitored 33 wolves across 11 packs in 2 interior B.C. study areas: Prince George South (PGS), characterized by extensive salvage logging features, and John Prince Research Forest (JPRF), also affected by salvage logging but less intensively. Because predation risk is a function of wolf density, space use, and predation patterns, we required a better understanding of these factors to develop management recommendations that could minimize predation risk to moose. Based on midwinter pack counts and home range size, wolf density was about 10 wolves/1,000 km 2 in PGS and 5 wolves/1,000 km 2 in JPRF. We identified 290 kills made by wolves, predominantly moose in PGS (87%) and JPRF (75%). Wolves in JPRF preyed on more elk and deer than did wolves in PGS, and at 10% of the kill sites we investigated in JPRF, wolves had killed black bears. We found moose calves at 27% of the moose kill sites, compared with midwinter estimates of standing proportions of calves in the population of 13-20%. After accounting for probability of the collared wolf attending pack kills, we calculated that wolf packs in PGS killed a moose every 4-8 days in winter and every 8-11 days in summer. In JPRF, wolf packs killed a moose every 7-12 days in winter and every 19-26 days in summer. However, when we considered the number of wolves per pack in the 2 study areas, the kill rates per wolf were similar. Based on recent midwinter moose density estimates , these kill rates would equate to 7-20% of the moose population for PGS and 2-8% of the moose population for JPRF. These predation rates may not be indicative of predation rates during the moose decline in the 2000s, so it is important to consider the mechanisms that could contribute to changing kill rates, including differential use by wolves and moose of highly modified landscapes and landscapes exposed to recent change such as widespread logging or wildfire. Based on our 2 study areas, extensive salvage logging creates habitat features that may support higher wolf densities and larger pack sizes, particularly in landscapes where moose are the dominant ungulate species.

Documenting forest juvenilization in high-elevation old-growth forests in southern inland British Columbia, with implications for the winter ecology of Canada’s endangered Deep-Snow Caribou

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May 2025

Climate change is altering high-elevation conifer forests in western North America, with potential impacts on species dependent on these ecosystems. We investigated recent, locally widespread tree mortality patterns in old-growth Engelmann spruce–subalpine fir forests in southern British Columbia, with special reference to the winter foraging needs of Canada’s endangered Deep-Snow Caribou (DSC), tied almost exclusively to heavy loading of arboreal hair lichens. We quantified the percentage of standing dead canopy trees across elevational gradients and examined relationships with stand characteristics in 120 plots along five vertical transects between 1650 and 2050 m. We found that an average of 31.1% of canopy trees were standing dead, with significantly higher rates (41.8%) below 1800 m than above 1900 m (11.5%). Subalpine fir (Abies lasiocarpa) had a higher percentage of standing dead trees (34.7%) than Engelmann spruce (Picea engelmannii, 15.5%). Upper elevation forests were significantly younger, consistent with post-Little Ice Age establishment. These findings suggest a forest transition process (forest juvenilization) that may initially increase DSC winter forage availability due to higher lichen loadings on standing dead trees. Looking forward, we project a long-term reduction in winter forage as old-growth structure is lost. Our study establishes baseline data for long-term monitoring and highlights the need for further research on the cascading effects of climate-induced forest changes on old-growth-dependent species like DSC.

Restoration of Coniferous Forest and Myodes gapperi: Responses to Thinning, Fertilization, and Succession over a 45-Year Period

Article

Full-text available

Jan 2025

Research Highlights: We report a 45-year time-line of forest restoration after harvesting and responses of red-backed voles (Myodes gapperi), an indicator species of closed-canopy forests. Background and Objectives: We have a unique long-term window to test four hypotheses that evaluated the relationship of M. gapperi with old forest structural attributes. Materials and Methods: The study began in old-growth lodgepole pine (Pinus contorta var. latifolia) through clearcutting, regeneration, stand thinning, fertilization, and growth to mature forest (1979 to 2024) in southern BC, Canada. Populations of red-backed voles were monitored in all phases of forest restoration. Results: Clearcutting resulted in the extirpation of M. gapperi followed by small (≤2 voles/ha) populations in young (13–23 years) thinned and fertilized stands. At age 33, the mean annual abundance of M. gapperi (6.5 to 8.7/ha) was highest in the heavily thinned and old-growth stands. At age 43, mean numbers of M. gapperi ranged from 2.7 to 4.2/ha in these same stands. Heavily thinned stands had large trees, multi-layered canopies of conifers, and understory patchiness. Conclusions: This is the first report of long-term responses of M. gapperi to the restoration of mature forest. M. gapperi is a suitable species for monitoring the recovery of some old forest structural features.

Glyphosate-based herbicide contributes to nutrient variability in forest plants

Article

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Dec 2024

In forestry, glyphosate-based herbicide (GBH) is applied to some logged areas to remove deciduous and herbaceous vegetation competing with commercial coniferous trees. Glyphosate has the potential to form insoluble complexes with metal ions, altering the bioavailability of metals in soil and water. The aim of this study was to determine if GBH influenced the concentrations of available nutrients in forest plants. We sampled willow (Salix sp.), red osier dogwood (Cornus sericea), and fireweed (Chamaenerion angustifolium) from forests up to 12 years after GBH applications. Across the three focal species, only Mn consistently increased with GBH treatment. Significant positive correlations between nutrient and glyphosate concentrations within plant tissues were found for Mn and Zn, while negative correlations were found for Ba, Ca, Mg, and Ni. B, Ca, Mn, and species were significant predictors of GBH treatment. A greater number of significant differences between controls and treated samples were noted in nutrients of fireweed and red osier dogwood at year one post-treatment, while willow showed greater differences between controls and treated samples at year 12 post-treatment. The analyses conducted indicate a relationship between GBH treatment and resulting nutrient regimes after GBH applications, yet it is complex and variable. It is clear that there are species specific trends within the dataset. Due to this complexity, more research should be conducted, as many questions remain unanswered. Further research is needed to disentangle both short and long-term impacts of widespread use of GBH products in modern silviculture.

Unraveling the interplay between phylogeny and chemical niches in epiphytic macrolichens

Article

Full-text available

Dec 2024
OECOLOGIA

This study aims to elucidate the connection between the phylogeny of epiphytic macrolichens and their chemical niches. We analyzed published floristic and environmental data from 90 canopies of Picea glauca x engelmannii across various forest settings in British Columbia. To explore the concordance between a principal coordinates analysis of the cladistic distance matrix and a global non-metric multidimensional scaling of the ecological distance matrix, we used Procrustean randomization tests. The findings uncover a robust association between large-scale macrolichen phylogeny and canopy throughfall chemistry. The high calcium-scores of the studied species effectively distinguished members of the Peltigerales from those of the Lecanorales, although parameters linked with Ca such as Mn, Mg, K, bark-, and soil-pH, may contribute to the niche partitioning along the oligotrophic—mesotrophic gradient. The substantial large-scale phylogenetic variation in the macrolichens’ Ca-scores is consistent with an ancient adaptation to specialized chemical environments. Conversely, the minor variation in Ca-scores within families and genera likely stems from more recent adaptation. This study highlights crucial functional and chemical differences between members of the Lecanorales and Peltigerales. The deep phylogenetic connection to the chemical environment underscores the value of lichens as transferable bioindicators for the chemical environment and emphasizes the importance of elucidating the intricate interplay between chemical factors and lichen evolution.

Influence of stand thinning on wildlife in managed second-growth forests: tree squirrels, small mustelids, and mammalian species richness

Article

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Nov 2024

Context Clearcutting of forests reduces food, cover, and stand structure attributes for tree squirrels (Tamiasciurus hudsonicus, Glaucomys sabrinus), small mustelids (Mustela richardsonii, Neogale frenata), and other mammal species. Forest restoration is urgently needed and stand thinning of second-growth forests may help restore habitats for mammals. Aims We tested the hypotheses that in thinned stands of second-growth lodgepole pine (Pinus contorta var. latifolia) at 30–36 years post-thinning: (H1) tree dimensions would be comparable to, or higher than those in uncut old-growth forest; activity of tree squirrels, weasels, and mammalian species richness would be higher in (H2) heavily thinned than lightly thinned stands, and (H3) higher in uncut old-growth forest than in second-growth thinned stands. Methods We measured stand structure attributes and activity of tree squirrels, weasels, and mammalian species richness with camera traps from 2021 to 2023 in replicated (n = 3) treatments of three densities of thinned pine stands and uncut old-growth forest in south-central British Columbia (BC), Canada. Key results Thinned and old-growth stands had mean tree diameters ranging from 18 to 22 cm, but mean tree heights were highest in the old-growth stands. Low-density stands tended to have large diameter crop trees with substantial crowns. There was no evidence for a difference in mean activity of T. hudsonicus and G. sabrinus, other common mammal species, and overall species richness among stands. There were more weasel detections per camera-day in the low-density and old-growth stands than other thinned stands. Conclusions Comparison of stand structure attributes showed partial support for H1. There was insufficient evidence to detect biologically meaningful effects among stands in a mean index of activity for T. hudsonicus, G. sabrinus, other common mammal species, and overall species richness, and hence did not support H2 or H3. There was weak support for H2 and H3 with limited weasel activity. Implications Thinned second-growth stands ≤1000 stems/ha may provide habitat at least for the mammal species and post-treatment period outlined in this study. To our knowledge, this is the first convergence of managed coniferous stands (age 43 years) with old-growth forest (age 140–187 years) in terms of some components of stand structure and mammalian species richness.

Description of a relict aspen parkland-associated grassland in the Peace River region of British Columbia, Canada

Article

Full-text available

Oct 2024
Can Field Nat

Nicholas P. Hamilton

The aspen parkland-associated grasslands of the Peace River region, British Columbia (BC), have been severely reduced in area, primarily because of agricultural and urban development. In this region, the species composition of plant communities is similar to that of prairie grasslands and is topographically influenced, occurring primarily on warm-aspect slopes along the Peace River and some of its tributaries. Historical records show that non-forested grass- and sedge-dominated plant communities occurred on flat and gently rolling terrain in a parkland ecosystem near what are now the communities of Dawson Creek and Fort St. John. The Peace grasslands are not represented in BC’s biogeoclimatic ecosystem classification, perhaps leading to their neglect in regional natural resource management and conservation planning. Here, I describe the vascular plant community of a level-terrain relict aspen parkland-associated grassland in the Peace River region. Its species composition differs from nearby warm-aspect grasslands and includes provincially listed plant species. Increased awareness of grassland communities may support conservation, ecosystem restoration, and climate change adaptation in the southern boreal region of BC.

Early spectral dynamics are indicative of distinct growth patterns in post‐wildfire forests

Article

Full-text available

Sep 2024

Western North America has seen a recent dramatic increase in large and often high‐severity wildfires. After forest fire, understanding patterns of structural recovery is important, as recovery patterns impact critical ecosystem services. Continuous forest monitoring provided by satellite observations is particularly beneficial to capture the pivotal post‐fire period when forest recovery begins. However, it is challenging to optimize optical satellite imagery to both interpolate current and extrapolate future forest structure and composition. We identified a need to understand how early spectral dynamics (5 years post‐fire) inform patterns of structural recovery after fire disturbance. To create these structural patterns, we collected metrics of forest structure using high‐density Remotely Piloted Aircraft (RPAS) lidar (light detection and ranging). We employed a space‐for‐time substitution in the highly fire‐disturbed forests of interior British Columbia. In this region, we collected RPAS lidar and corresponding field plot data 5‐, 8‐, 11‐,12‐, and 16‐years postfire to predict structural attributes relevant to management, including the percent bare ground, the proportion of coniferous trees, stem density, and basal area. We compared forest structural attributes with unique early spectral responses, or trajectories, derived from Landsat time series data 5 years after fire. A total of eight unique spectral recovery trajectories were identified from spectral responses of seven vegetation indices (NBR, NDMI, NDVI, TCA, TCB, TCG, and TCW) that described five distinct patterns of structural recovery captured with RPAS lidar. Two structural patterns covered more than 80% of the study area. Both patterns had strong coniferous regrowth, but one had a higher basal area with more bare ground and the other pattern had a high stem density, but a low basal area and a higher deciduous proportion. Our approach highlights the ability to use early spectral responses to capture unique spectral trajectories and their associated distinct structural recovery patterns.

2024 Pink Mountain Plains Bison Aerial Survey Results - Minimum Count

Technical Report

Full-text available

Mar 2024

Chris Lewis

A minimum population count aerial survey was conducted for the Pink Mountain plains bison in the Halfway-Sikanni River area, northwest of Fort St. John, BC. The survey was conducted between March 1st to March 3rd, 2024, and covered the entire suspected plains bison winter range. Snow conditions were good, and temperatures during the survey ranged from -28⁰C to -20⁰C. The objectives of the survey were to estimate the minimum number of plains bison, the bull/cow ratio, and the calf/cow ratios. Survey methodology followed modified protocols from the 2014 Halfway-Sikanni plains bison inventory (Lirette 2015) and the Resources Information Standards Committee (RISC) standards (RISC 2002). The 2014 survey area was enlarged to include areas of suspected range expansion. Additional survey time, effort and area, outside the 2014 survey flight lines, were flown to ensure no bison were missed outside of the survey area. A total of 144 bison were observed during the survey composed of 47 bulls, 50 cows, 15 calves, 7 yearlings, and 22 unclassified bison. Average group size was 8.0 with a maximum group size of 20 bison. The observed bull/cow ratio was 94 bulls per 100 cows and the observed calf/cow ratio was 30 calves per 100 cows. Hunting regulation review is recommended along with future aerial surveys using marked/tagged animals for estimates of sightability and camera trap surveys in high use areas.

Differential response by seedlings of three sub-boreal conifer species to high- and low-carbon wood ash amendment

Article

Full-text available

Aug 2024

In Canada, there is a need to implement value-added uses for wood ash (hereafter ash) generated from bioenergy facilities as most ash is landfilled. Ash application to forests can provide benefit via nutrient supply, amelioration of soil acidity and, sometimes, increased tree growth. However, information is limited on the response of conifer species to different wood ash types applied to fine-textured soil typical of north-central B.C. We conducted a 16-month seedling pot trial that examined the response of Douglas-fir (Pseudotsuga menziesii), lodgepole pine (Pinus contorta var. latifolia), and hybrid white spruce (Picea glauca × engelmannii) to high- (HCA) and low-carbon ashes (LCA) applied (up to 10 Mg mineral matter ha⁻¹ equiv.), with and without fertilizer N (200 kg N ha⁻¹ equiv.), to fine-textured forest soil. Pine and spruce exhibited a 1.6- and 1.4-fold increase in shoot biomass at the high rate of HCA with fertilizer N. At study end, the high rate of LCA had the greatest soil pH, EC and total K in the upper forest floor, but the HCA had greater total B, P and Zn. LCA elicited increased foliar B in pine, but HCA increased foliar Ca in spruce when co-applied with fertilizer N. In general, Douglas-fir growth did not respond to ash treatments, and seedling mortality was observed in some LCA treatments. Ash treatments helped offset some nutrient deficiencies induced by N fertilization. Ash type influenced soil chemical as well as seedling growth and nutrition responses.

Logging disturbance, hydrology, and geomorphic context determine suspended fine particulate organic matter concentrations in forested coastal headwater streams: A 10-year forest management experiment

Article

Full-text available

Aug 2024
FOREST ECOL MANAG

Headwater streams are important sources of water and materials supporting food webs in downstream habitats, and are considered sensitive to forest disturbance. We manipulated 13 headwater stream catchments draining ~70 year-old coniferous-dominated coastal forests near Vancouver, Canada to investigate the modifying influence of riparian buffers on the effects of clear-cut logging on suspended fine particulate organic matter (FPOM: > 0.50 μm and < 1.0 mm) concentrations. FPOM is a predominant food source for invertebrates and serves as a longitudinal link in river food webs. Riparian logging treatments (n = 3-4 replicates/treatment) represented a gradient of disturbance intensity including clear-cut to the stream edge (highest level of disturbance), clear-cut with 10-m and 30-m wide fully forested buffers (medium high and medium disturbance, respectively), and forested controls (natural disturbance levels). To measure suspended FPOM (mg⋅L-1 ⋅km-2), we collected water samples during discrete sample events biweekly to seasonally before (1997-1998) and after (1998-2007) timber harvest (FPOM D) and continuously using an automatic water sampler (FPOM C) during storm events the first three years after logging. The response ratio, an effect size metric which measures the proportionate change in FPOM D after logging relative to before, declined over time in all treatments. However, the rate of decline was almost two times faster in the clear-cut and 10-m buffer treatments compared to other treatments. Furthermore, during storm events FPOM C concentrations increased at faster rates with unit increase in discharge in the clear-cut and 10-m buffer treatments relative to the other treatments indicating higher transport capacities. We hypothesize that FPOM D declined at faster rates in the clear-cut and 10-m buffer treatments due to a variety of interdependent factors including lower organic matter inputs and higher loss rates. In addition to the effects of logging on FPOM, we found that FPOM concentration was also strongly influenced by natural hydrologic and geomorphic factors, including discharge and channel gradient.

Forest Disturbance Thresholds and Cumulative Hydrological Impacts

Article

Full-text available

May 2024
WATER RESOUR RES

Forest disturbance threshold is defined as a critical disturbance level (e.g., % of forest cover change) in forested landscapes above which significant hydrological impacts are detected. Determining disturbance thresholds is critically important for supporting forest management to ensure the sustaining of ecological and hydrological functions. However, there are very few quantitative evaluations of forest disturbance thresholds globally. In this study, we applied a well‐tested methodology (the modified double mass curve) to derive the long‐term, continuous hydrological response curves and then to quantify forest disturbance thresholds on annual streamflow in 42 forested watersheds in British Columbia, Canada. The results show that forest disturbance thresholds for significant and cumulative hydrological impacts vary from 7% to 52% of cumulative equivalent clear‐cut area with an average of 17% or from 8% to 52% of disturbed area with an average of 19%. Climate (inter‐annual and intra‐annual) and watershed properties exert critical controls on forest disturbance thresholds. Watersheds with greater snowfall proportions (more annual precipitation falling as snow), more desynchronizations (temporal mismatching) of energy demand and water supply at the intra‐annual scale, less diverse ecosystems, and larger watershed sizes have lower forest disturbance thresholds. Given the present forest disturbance levels in the central interior of British Columbia, about half (53%) of the forested watersheds have already crossed the average disturbance threshold. These results highlight that watershed planning and management using forest disturbance thresholds must carefully consider local climate and watershed properties. The methodology can be effectively and robustly extended elsewhere around the globe.

Long-term riparian forest loss around streams, lakes, and wetlands in ecologically diverse managed and unmanaged landscapes

Article

Full-text available

Apr 2024
FOREST ECOL MANAG

Riparian forests are at risk from the cumulative effects of human and natural disturbance. We assessed the magnitude and rate of forest loss adjacent to freshwater features in the province of British Columbia, Canada, from 2000 to 2021. We used Global Forest Change data to quantify percent tree cover lost annually across six ecologically and topographically diverse ecosections containing 361,370 streams, lakes, and wetlands. We stratified the aquatic features into large and small size classes within and outside parks. We hypothesized that cumulative forest loss would be greater outside of parks as a consequence of human-caused and natural disturbance. Also, we hypothesized greater rates of forest loss around small aquatic features that generally receive less protection outside of parks. Loss of riparian forest was consistently greater outside of parks (median losses of 3.20% versus 1.29%), and adjacent to small streams (median = 3.31%) and wetlands regardless of size (median = 3.10%). Rates of cumulative riparian forest loss were nonlinear, increasing substantially in 2013. Though the annual riparian forest losses were small, the cumulative losses from 2000 to 2021 were substantial. We anticipate the continued loss of riparian forest as climate changes and natural disturbances intensify. We recommend further investigation of the implications of these observed trends for ecosystem values that are found within or adjacent to riparian forest across managed and unmanaged landscapes.

Southern Interior Forest Region Forest Management Options for Interior Dry Forest Ecosystems: The Opax Mt. and Isobel Research Trials

Article

Full-text available

Jan 2006

Population fluctuations of meadow voles (Microtus pennsylvanicus) in a landscape with cumulative clearcutting

Article

Apr 2024

We investigated the responses of meadow vole (Microtus pennsylvanicus) populations to cumulative clearcutting of coniferous forests during four Periods over a 42-year span from 1979 to 2020 near Summerland, British Columbia, Canada. This vole is a common inhabitant of moist meadows, grasslands, and early successional sites after forest clearcutting and wildfire and may damage plantation trees on reforestation sites. We tested three hypotheses (H) that populations of M. pennsylvanicus would (H1) increase in abundance and potentially fluctuate owing to the availability of early seral post-harvest habitats associated with cumulative clearcut harvesting; and (H2) be positively associated with mean cover of herbaceous vegetation on clearcut sites; and (H3) be at lower abundance when the long-tailed vole (M. longicaudus) is present at higher numbers. Overall, mean abundances of M. pennsylvanicus were generally low, and hence differences among Periods were not formally significant. Thus, H1, that meadow voles would increase in abundance on new clearcuts was not supported, except for Period 2 with the highest mean density recorded at 14.3 voles/ha. There was some evidence of a 4-year multi-annual fluctuation in 1998 and 2002 in Period 2. Mean ground cover of total herbs, grasses, and shrubs were similar in Periods 2 and 3. However, meadow vole populations were dramatically different in these two Periods, with few meadow voles captured in Period 3 and then a decline to extirpation in Period 4. Thus, H2 was supported for Period 2, but not Period 3. Both species of voles were present at similarly low numbers (< 5/ha) with fewer meadow voles in the three years of peak numbers (22–33/ha) of long-tailed voles, and hence this pattern provided weak support for H3. The lack of increases in meadow vole numbers post-cutting in Periods 1, 3, and 4 may have been related to very high numbers of M. longicaudus in Period 1 and possibly the advent of cattle grazing and drought conditions in Periods 3 and 4. Although the decline in Microtus on post-harvest forest sites may be beneficial for pest management and reforestation, such declines may have serious consequences for predator communities, biodiversity, and other ecological functions.

Enhanced watershed status evaluation: Towards an integrated framework to assess fish habitat in forested watersheds using airborne laser scanning data

Article

Full-text available

Mar 2024
FOREST ECOL MANAG

The Texas Creek landslide, southwestern British Columbia: new ages and implications for the culture history and geomorphology of the mid-Fraser River region

Article

Full-text available

Feb 2024

The Texas Creek rock avalanche is a prehistoric deposit in the Fraser River Canyon, 17 km south of Lillooet, southwestern British Columbia, Canada. Original mapping suggested that the debris consisted of two landslides: a 45 Mm³ event deposited after the Mazama tephra but before about 2 ka ago, and a 7.2 Mm³ event about 1.1 ka ago. The proposed timing of the younger landslide was correlated with a decline in the First Nations population and was proposed as an agent of cultural collapse driven by its impact on salmon returns vital to the population's sustenance. We provide six surface exposure ages using ¹⁰Be from boulder tops, with three samples from each surface that were originally posited to be older and younger debris. The six samples yielded similar ages suggesting the landslide deposit represents a single event with an average age of 2.28 ± 0.19 (2σ external error) ka before 1950 AD. Evidently, the landslide played no role in the cultural collapse. Fraser River Holocene incision rates, estimated pre- and post-landslide are between 13 and 24 mm/yr, consistent with previous estimates for the mid-Fraser River region. Landslide timing is coincident with the explosive eruption of Mount Meager, 120 km to the northwest, and with a possible landslide at Mystery Creek 85 km to the west and 65 km south of Mount Meager. The landslide may have been seismically triggered, but attribution is speculative.

Landsat assessment of variable spectral recovery linked to post-fire forest structure in dry sub-boreal forests

Article

Feb 2024
ISPRS J PHOTOGRAMM

Temperature requirements for western balsam bark beetle (Dryocoetes confusus Swaine (Coleoptera: Curculionidae: Scolytinae) development in southern British Columbia

Article

Full-text available

Jan 2023

The western balsam bark beetle, Dryocoetes confusus, is the primary biotic disturbance that is causing accelerated subalpine fir mortality in northern and high-elevation forests in southern British Columbia, Canada. The province's climate has warmed dramatically over recent decades and is affecting many biological processes, including those of D. confusus and its host, subalpine fir, Abies lasiocarpa (Pinaceae). Dryocoetes confusus generally undergoes a two-year life cycle, with larvae and teneral adults each overwintering once. To determine whether a univoltine life cycle would be possible, we reared D. confusus from field-and laboratory-infested logs under five constant temperature regimes between 18 °C and 24 °C, with and without cold treatments. Under the coolest regime (18 °C), insect development was arrested in the late larval stage, indicating that an environmental cue is needed for development to proceed or not. At temperatures higher than 21 °C, D. confusus displayed continuous development to teneral adulthood and emergence without requiring a cold period. Our results demonstrate that D. confusus does not have an obligatory diapause, requires 1200 degree-days to complete development, and under warming field conditions, the beetle may be able to switch to a univoltine life cycle. A life cycle contraction could have enormous implications to the future health of subalpine fir forests.

Assessing the harvest sustainability of black bears on central Vancouver Island

Research

Full-text available

Aug 2023

Black bears (Ursus americanus) serve an ecological role in the coastal temperate ecosystems on Vancouver Island. They are valued by Indigenous communities, and sightings are part of the Vancouver Island experience for residents and tourists alike. Harvest management of black bears in British Columbia (B.C.) has relied on harvest data, though this data does not allow for a direct assessment of harvest sustainability. Prior to this project, field-based population inventories focussed on black bears have not been conducted on Vancouver Island, nor anywhere in B.C. We undertook a field-based, mark-recapture program in Wildlife Management Units (WMUs) 1-4 and 1-5 in central Vancouver Island in 2021. Our objectives were to provide guidance for the design of future spatial mark-recapture inventories for black bears in coastal B.C., estimate the population size of black bears in WMUs 1-4 and 1-5, and assess the sustainability of licensed black bear harvest and conflict mortality in these areas by calculating a putative harvest rate and conflict kill rate. We had 267 black bear detections at unique site-session combinations, resulting in the identification of 177 individual bears (112 males and 65 females). We assessed spatial covariate (vegetation, road density, access/land ownership) relationships with density and determined that these pilot data were too sparse to produce reliable relationships between covariates and density. Our estimate of black bear density was 569 bears per 1,000 km 2 (95% CI: 404-800), which is higher than many black bear densities along the west coast of North America. Average harvest rates (3% and 8%) and percent females in the harvest (23%) were similar to other areas in B.C., within the ranges of neighboring jurisdictions, and generally within reported sustainable limits. The recorded conflict mortality rates for black bears were low at 0.3% of the estimated population in both management units. The overall mortality (harvest + conflict kill) rates remained below mortality rate thresholds, though we suspect there are localized areas around communities where the mortality rate exceeds sustainable levels. This source-sink dynamic is created when areas in and around communities attract bears because unnatural food is abundant and risk of mortality from other bears is low. We suggest future coastal black bear inventories use 2.5-3 km trap spacing (~9 km 2 grid cells) with 3x5 trap cluster configuration. Trap clusters should be spaced > 40 km apart and cover areas with known or suspected differences in bear density and mortality. We recommend combining future black bear inventories on Vancouver Island with this study to more precisely estimate black bear density and evaluate the sustainability of human-caused mortality at several scales.

Pop-up restoration in colonial contexts: applying an indigenous food systems lens to ecological restoration

Article

Full-text available

Sep 2023

As environmental injustices and their disproportionate harms to Indigenous communities are increasingly acknowledged, restoration strategies are being deployed widely by environmental NGOs, resource extraction industries, and government agencies. The inclusion of Indigenous communities and their knowledges in restoration efforts are often considered progress in the pursuit of ecological reconciliation. However, in some cases we have observed a lack of meaningful progress as settler colonial prescriptions for land-healing can eschew efforts to decolonize ecological restoration — what we have labeled “pop-up restoration.” We consider two restoration efforts underway in St’at’imc and Quw’utsun territories (Canada) and contrast them with what we are learning alongside the communities’ own values and efforts to reclaim and revitalize food systems throughout forest, wetland, and grassland systems. Utilizing culturally appropriate pathways, we then evaluate how applying an Indigenous Food Systems lens to ecological restoration may provide a framework to remedy pop-up restoration, confronting settler colonial aspirations to transform Indigenous homelands while asserting justice in ecological restoration contexts.

Species-Specific Responses to Human Trampling Indicate Alpine Plant Size Is More Sensitive than Reproduction to Disturbance

Article

Full-text available

Aug 2023

Human disturbance, such as trampling, is an integral component of global change, yet we lack a comprehensive understanding of its effects on alpine ecosystems. Many alpine systems are seeing a rapid increase in recreation and in understudied regions, such as the Coast Mountains of British Columbia, yet disturbance impacts on alpine plants remain unclear. We surveyed disturbed (trail-side) and undisturbed (off-trail) transects along elevational gradients of popular hiking trails in the T’ak’t’ak’múy’in tl’a In’inyáxa7n region (Garibaldi Provincial Park), Canada, focusing on dominant shrubs (Phyllodoce empetriformis, Cassiope mertensiana, Vaccinium ovalifolium) and graminoids (Carex spp). We used a hierarchical Bayesian framework to test for disturbance by elevation effects on total plant percent cover, maximum plant height and diameter (growth proxies), and buds, flowers, and fruits (reproduction proxies). We found that trampling reduces plant cover and impacts all species, but that effects vary by species and trait, and disturbance effects only vary with elevation for one species’ trait. Growth traits are more sensitive to trampling than reproductive traits, which may lead to differential impacts on population persistence and species-level fitness outcomes. Our study highlights that disturbance responses are species-specific, and this knowledge can help land managers minimize disturbance impacts on sensitive vegetation types.

The effect of season and urbanisation on Calliphoridae (Diptera) diversity in British Columbia, Canada, using baited traps

Article

Full-text available

Jul 2023

Forensic entomology is an important component of criminal investigations, providing information surrounding a death using region-specific data on the local necrophagous community. To understand the community within the Metro Vancouver region of British Columbia, Canada, a field study monitored the abundance and diversity of necrophagous Calliphoridae (Diptera) over a nine-month period in distinct terrestrial environments. Baited bottle traps ( n = 9) were deployed weekly for 12-hour intervals in three different environments. Species, sex, and gravidity of collected specimens were determined. Bivariate analyses revealed significant relationships between species, geographic location, and month of collection, suggesting that Calliphoridae species composition is influenced by habitat type and seasonal shifts in temperature. Sex ratios and reproductive ranges of Calliphoridae differed among the habitats sampled.

Heat Wave, Cone Crops, Forest-Floor Small Mammals, and Mustelid Predation in Coniferous Forests of Southern British Columbia

Article

May 2025

We report a landscape-scale natural experiment that followed the abundance and demography of forest-floor small mammals and the activity of small mustelids over a 4-year period of an extreme heat wave and abundant coniferous cone crops. Deer mice (Peromyscus maniculatus) and southern red-backed voles (Myodes gapperi) are major species in the coniferous forest-floor small mammal community near Summerland in southern British Columbia, Canada. Their major mammalian predators include the short-tailed weasel (Mustela richardsonii), long-tailed weasel (Neogale frenata), and American marten (Martes americana). We evaluated three hypotheses (H) that may explain the changes in these mammals from 2021 to 2024: (H1) that large coniferous cone crops in 2022 would have generated high populations of forest-floor small mammals in 2023 owing to enhanced reproductive output and overwinter survival; (H2) that increased activity of mustelids would have followed population increases, resulting in the decline of small mammal prey in 2024; and (H3) that the widespread occurrence of cone crops in 2022 would also have elicited the same mammalian responses in 2023 at a second study area (Golden, BC) 276 km and three mountain ranges from Summerland. During the summer periods of each year, small mammal populations were monitored by intensive live-trapping, and mustelid presence was measured via an index of activity based on live traps, fecal scats, and predation events. The mean abundance and reproductive performance of the P. maniculatus and M. gapperi populations increased in response to the coniferous seedfall, thereby supporting H1. The activity of small mustelids responded positively to increased numbers of small mammal prey and potentially acted in a regulatory and top–down function in these communities, and hence partially support H2. Similar responses at Summerland and Golden indicated that this seedfall event and changes in the mammalian community occurred at a landscape-scale, thereby providing partial support for H3. Potential differential effects of large seed crops on consumers did not affect the mean abundance patterns for P. maniculatus but apparently reduced this metric for M. gapperi. Heat waves, induced by anthropogenic climate change, may alter the frequency of coniferous masting events, and their effects may temporarily change the number and species of mammalian seed consumers and their predators.

Evaluation of a drone to map and monitor critical habitat features for the Sage Thrasher (Oreoscoptes montanus)

Article

Full-text available

May 2025

Habitat destruction is the leading cause of global biodiversity loss. To recover endangered species requires knowing the habitat elements that are essential to their survival, defined as critical habitat. This paper demonstrates the application of unoccupied aerial vehicles (UAVs), for the recovery of habitat for endangered species. We establish a replicable methodology for surveying and monitoring potentially suitable nest shrubs for Sage Thrashers (Oreoscoptes montanus) using an Aeryon SkyRanger. We trialed the methodology in winter when operational demands are minimal and before the birds return to breed. We found drone image analysis aligned well with field assessments of Artemisia tridentata height and may present a cost-efficient approach for mapping and monitoring critical habitat features for nesting Sage Thrashers. The UAV classification accuracy was 100% for nest shrubs and 85% for non-nest shrubs (p-value < 0.001). We found the UAV-based method over-estimated the height of shrubs compared to the field-based measurements, where the 80 cm threshold for a suitable shrub corresponded to 73 cm as measured in the field (regression slope of 1.43, with an adjusted R² = 0.75, p-value < 0.0001). The approach also holds promise for other sagebrush steppe species of conservation concern.

Moisture transport to British Columbia’s upper Nechako Watershed associated with three atmospheric rivers

Article

Full-text available

Apr 2025

Atmospheric rivers (ARs) that reach British Columbia’s (BC’s) Coast Mountains undergo orographic lifting, leading to intense precipitation that impacts the region’s hydroclimatology. To assess the impact of ARs on the upper Nechako Watershed, the Tahtsa Ranges Atmospheric River Experiment (TRARE) collected detailed hydrometeorological data in this region during September and October 2021. For three case studies, primary pathways of moisture transport, water vapor budgets, and constancy of moisture transport across the upper Nechako Watershed are identified and quantified using TRARE observational and ERA5 reanalysis datasets. ARs associated with Events 3 and 5 had a southwest-to-northeast path with minimal temporal moisture variability. In contrast, Event 10 primarily followed a southeasterly-to-northwesterly pathway exhibiting more variable moisture transport. Although Events 3 and 5 are associated with weak ARs and Event 10 is indirectly linked to bombogenesis, they all contributed similar amounts (~ 10^9 kgs^-1) to the water vapor budget for the upper Nechako. Additionally, stronger winds and higher steadiness of moisture transport are associated with copious precipitation across the upper Nechako, particularly along the basin’s southern and western boundaries. ARs that impact the upper Nechako therefore play a crucial role in replenishing water resources that sustain ecological systems, aquatic habitat, hydropower generation, and domestic water consumption.

Zone Matcher: A climate-based web application for deployment and assisted migration of forest trees

Preprint

Full-text available

Apr 2025

Populations of forest trees are generally adapted to the climates they inhabit. The farther trees are moved from their local climates, the more long-term growth and survival tend to decrease. Current tree deployment and assisted migration rely on 'climate distance thresholds' (CDTs), which are climatic distances beyond which tree performance is considered unacceptable. Fixed zone systems, which have been used to guide deployment of native or orchard seedlots for more than 50 years, usually consist of contiguous geographic areas (zone units) divided into elevational bands (zones). In contrast, focal zone systems allow seed transfer among fixed zones that have similar climates. By using recent historical climates and future climate projections, focal zones can be used for current tree deployment or assisted migration. We developed a focal-zone system for the Pacific Northwest region of North America. First, we worked with stakeholders to select the base zones for the system. These consisted of geographic zone sets from Washington, Oregon, California, and Idaho/western Montana, and ecological zone sets from the U.S. and British Columbia. Second, by analyzing climate variation across the region, we developed a normalized Euclidean climate distance function consisting of nine climate variables from ClimateNA. Third, we inferred CDTs from analyses of climate variation within the base zones and from provenance tests. Fourth, we compared seed deployment areas using the fixed zone versus focal zone system, with and without assisted migration. Finally, we developed the Zone Matcher web application which implements our focal zone system. Across the region, we identified climate matches among 4,393 partially overlapping zones covering approximately 252 M ha. The unique area covered by these zones was about 167 M ha. Compared to fixed zones, our focal zone system increased the deployment area about 17- to 35-fold for the ecological zones and 70- to 300-fold for the geographic zones. This expands seed deployment options, allows more seedlots to be considered for a planting site, facilitates assisted migration, and simplifies sharing of seedlots among organizations. In addition to climate, seed transfer should also consider factors such as plantation soils, microtopography, and projections of competing vegetation, insects, diseases, and fire.

Drought tolerance to overwatering, periodic underwatering and complete withholding of water in interior Douglas-fir seedlings

Article

Oct 2024

Neoglaciation, Glacier-dammed Lakes, and Vegetation Change in Northwestern British Columbia, Canada

Article

May 2018

Pilosella spp., Hawkweeds / Piloselles (Asteraceae)

Chapter

Aug 2024

Growth trends clustering: A novel method for detecting forest disturbances and extracting climate signals in tree rings

Article

Jul 2024
SCI TOTAL ENVIRON

American Goshawk Diet on the South Coast of British Columbia, Canada

Article

Feb 2024

Effective wildlife conservation requires understanding diet composition and its consequences for population demography. Generalist predators consume a wide range of prey species and are therefore less sensitive to changes in prey abundance than specialists, but their reproductive success can still be driven by a primary prey species. We assessed breeding season diet of an at-risk population of American Goshawks (Accipiter atricapillus) across two ecological zones (coastal and transitional) on the south coast of British Columbia. We used three methods: egested pellets, prey remains, and nest cameras. We further assessed the impact of diet specialization and diet diversity on goshawk productivity. Diet composition and diversity differed among sample sources (pellets, pooled pellets-and-remains, cameras) and between measurements (biomass vs. counts of prey items), highlighting the importance of transparent methodology in raptor diet studies. Goshawks consumed 32 identified prey species but pine squirrels (Tamiasciurus spp.) dominated their diet in both ecological zones (14–61% of biomass), which indicated that pine squirrels may be a primary prey for this population. Diet of coastal zone goshawks contained slightly more birds and fewer hares than diet of transitional zone goshawks, consistent with the hypothesis that goshawk diet reflects local prey abundance. Goshawk pairs at 12 nests monitored with nest cameras fledged 1.4 ± 0.8 young per nest, but we found no evidence to support a correlation between diet diversity or dietary specialization and goshawk productivity. Our results suggest goshawks in this region act as functional specialists on locally abundant prey resources, but more research is needed to understand how variation in prey abundance affects goshawk diet and demographics in this temperate rainforest generalist. La conservación efectiva de la vida salvaje requiere comprender la composición de la dieta y sus consecuencias para la demografía poblacional. Los depredadores generalistas consumen una amplia variedad de especies presa y, por lo tanto, son menos sensibles a los cambios en la abundancia de presas que los especialistas, pero su éxito reproductivo aún puede depender de una especie presa principal. Evaluamos la dieta durante la temporada de cría de una población en riesgo de Accipiter atricapillus a lo largo de dos zonas ecológicas (costera y de transición) en la costa sur de la Columbia Británica. Utilizamos tres métodos: egagrópilas regurgitadas, restos de presas y cámaras de nidos. Además, evaluamos los impactos de la especialización y de la diversidad de la dieta en la productividad de A. atricapillus. La composición y la diversidad de la dieta difirieron entre las fuentes de muestreo (egagrópilas, egagrópilas y restos combinados, cámaras) y entre las mediciones (biomasa vs. recuento de presas), destacando la importancia de utilizar una metodología transparente en los estudios de dieta de rapaces. Los individuos de A. atricapillus consumieron 32 especies de presas identificadas, pero las ardillas de pino (Tamiasciurus spp.) dominaron su dieta en ambas zonas ecológicas (14–61% de la biomasa), lo que indica que las ardillas de pino pueden ser una presa principal para esta población. La dieta de los individuos de A. atricapillus de la zona costera incluyó ligeramente más aves y menos liebres que la dieta de los individuos de la zona de transición, lo que es consistente con la hipótesis de que la dieta de A. atricapillus refleja la abundancia local de presas. Las parejas de A. atricapillus en 12 nidos monitoreados con cámaras en nido criaron 1.4 ± 0.8 juveniles por nido, pero no encontramos evidencia que respalde una correlación entre la diversidad o la especialización de la dieta y la productividad de A. atricapillus. Nuestros resultados sugieren que A. atricapillus en esta región actúa como un especialista funcional sobre los recursos de presas localmente abundantes, pero se necesita más investigación para comprender cómo la variación en la abundancia de presas afecta la dieta y la demografía de A. atricapillus, una especie generalista del bosque templado. [Traducción del equipo editorial]

DNA barcoding aids in generating a preliminary checklist of the lichens and allied fungi of Calvert Island, British Columbia: Results from the 2018 Hakai Terrestrial BioBlitz

Article

Full-text available

Feb 2024

Bioblitzes are a tool for the rapid appraisal of biodiversity and are particularly useful in remote and understudied regions and for understudied taxa. Lichens are an example of an often overlooked group, despite being widespread in virtually all terrestrial ecosystems and having many important ecological functions. We report the lichens and allied fungi collected during the 2018 terrestrial bioblitz conducted on Calvert Island on the Central Coast of British Columbia, Canada. We identified 449 specimens belonging to 189 species in 85 genera, increasing the total number of species known from Calvert Island to 194, and generated Internal Transcribed Spacer (ITS) sequences for 215 specimens from 121 species. Bryoria furcellata , Chaenothecopsis lecanactidis and C. nigripunctata were collected for the first time in British Columbia. We also found Pseudocyphellaria rainierensis , which is listed as Special Concern on the federal Species at Risk Act, and other rarely reported species in British Columbia including Opegrapha sphaerophoricola , Protomicarea limosa , Raesaenenia huuskonenii and Sarea difformis . We demonstrate that DNA barcoding improves the scope and accuracy of expert-led bioblitzes by facilitating the detection of cryptic species and allowing for consistent identification of chemically and morphologically overlapping taxa. Despite the spatial and temporal limitations of our study, the results highlight the value of intact forest ecosystems on the Central Coast of British Columbia for lichen biodiversity, education and conservation.

Vegetation Quality Assessment: a sampling-based, loss-gain accounting framework for native, disturbed and reclaimed vegetation

Preprint

Full-text available

Sep 2023

Governments and society increasingly are demanding that industrial projects result in a net positive impact (NPI) on biodiversity. Impacts are commonly measured in terms of losses and gains of area and quality of vegetation, where quality refers to how closely a site matches the condition of native vegetation in its undisturbed state. Existing vegetation quality frameworks share a number of limitations, including little or no replication, uncertain scope of inference, vulnerability to bias, and inability to measure error. Here we present the Vegetation Quality Assessment (VQA) framework, a sampling-based extension of Quality Hectares that measures vegetation quality in terms of overlap between the probability distributions of ecological indicators at a project site and in undisturbed (benchmark) vegetation of the same kind. Distribution overlap incorporates natural variation at the landscape scale and provides an intuitive measure of quality that varies between 0 and 1. Indicators are measured using a stratified-random sampling design that minimizes bias and supports inference at the scale of the project landscape. Confidence limits of quality and quality hectares are determined by bootstrapping; power and minimum sample sizes are estimated by Monte Carlo simulation. Multiple assessments track losses and gains of quality hectares and enable accurate accounting of progress to NPI. The VQA framework can be implemented using a variety of vegetation sampling methods, allowing existing vegetation databases to be leveraged as sources of data. We conclude by demonstrating the application of VQA at several mining operations in the Elk Valley of southeastern British Columbia, Canada.

Leaf litter decomposition rates in freshwaters differ by ecosystem

Article

Sep 2023

Terrestrial leaf litter is a large contributor to the metabolism and secondary production of freshwaters. Decomposition rates of leaf litter in freshwaters are often used as a proxy for ecosystem function; however, there are many sources of variation in decomposition rates within and between freshwater ecosystems that still have not been tested. In particular, the variation in decomposition rates between different freshwater ecosystems has rarely been addressed. Here, we compared decomposition rates of red alder (Alnus rubra) leaf litter in streams, ponds, and lakes within a single forest, while controlling for water temperatures. Using coarse-mesh and fine-mesh bags we found that when accounting for degree days, decomposition rates were higher in streams than ponds, and twice as high in streams than lakes, for either mesh size. The overall densities of invertebrates per leaf pack or per gram of leaf litter were very similar between the three ecosystems. However, detritivores were six-fold or more abundant in leaf packs from streams than those from lakes or ponds. There were fewer specialized macroinvertebrate consumers of leaf litter in the lentic environments. Specialized shredders such as Plecoptera were absent from lentic sites, and their absence in terms of decomposition rates was not compensated for by litter decomposition by generalist taxa. While we did not test the specific mechanisms responsible, differences may be associated with the relative temporal and spatial variation in the abundance of this resource and lack of specialist consumers in lakes and ponds.

Kilgii Gwaay: An Early Maritime Site in the South of Haida Gwaii

Chapter

Jan 2005

Ecosystems of British Columbia

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