Interior British Columbia Research Articles

Past Groundwater Drought in the North American Cordillera

AbstractGroundwater level records in North America are relatively short (<60 years), preventing long‐term analysis of historical changes in groundwater levels associated with drought. In this study, tree ring widths are used to reconstruct groundwater levels in three regions in the North American Cordillera: Central British Columbia (BC), Canada, the Southern Interior Region of BC, and the San Luis Valley in Colorado, USA. Periods with severe drought conditions, identified using regime shift and threshold analyses were: 1890–1900 and 1950–1970 in Colorado, around 1920–1940 in the BC Interior, and 1935–1945 in Central BC. The groundwater level reconstructions are correlated with several climate indices and have similar regime shifts as identified in streamflow and drought records. The groundwater level reconstructions are strongly related to winter snowpack, suggesting that the observed trend of declining snowpack in recent years may lead to declining groundwater availability in these regions.

Seasonal shifts in depth-to-water uptake by young thinned and overstocked lodgepole pine (Pinus contorta) forests under drought conditions in the Okanagan Valley, British Columbia, Canada

Abstract. As drought and prolonged water stress become more prevalent in dry regions under climate change, preserving water resources becomes a focal point for maintaining forest health. Forest regeneration after forest loss or disturbance can lead to overstocked juvenile stands with high water demands and low water-use efficiency. Forest thinning is a common practice with the goal of improving tree health, carbon storage, and water use while decreasing stand demands in arid and semi-arid regions. However, little is known about the impacts of stand density on seasonal variation in depth-to-water uptake or the magnitude of the effect of growing season drought conditions on water availability. Existing reports are highly variable by climatic region, species, and thinning intensity. In this study, stable isotope ratios of deuterium (δ2H) and oxygen (δ18O) in water collected from various soil depths and from branches of lodgepole pine (Pinus contorta) under different degrees of thinning (control: 27 000 stems per hectare; moderately thinned: 4500 stems per hectare; heavily thinned: 1100 stems per hectare) over the growing season were analyzed using the MixSIAR Bayesian mixing model to calculate the relative contributions of different water sources in the Okanagan Valley in the interior of British Columbia, Canada. We found that under drought conditions the lodgepole pine trees shifted their depth-to-water uptake through the growing season (June to October) to rely more heavily on older precipitation events that percolated through the soil profile when shallow soil water became less accessible. Decreased forest density subsequent to forest thinning did not cause a significant difference in the isotopic composition of branch water but did cause changes in the timing and relative proportion of water utilized from different depths. Thinned lodgepole pine stands were able to maintain water uptake from 35 cm below the soil profile, whereas the overstocked stands relied on a larger proportion of deep soil water and groundwater towards the end of the growing season. Our results support other findings by indicating that, although lodgepole pines are drought-tolerant and have dimorphic root systems, they do not shift back from deep water sources to shallow soil water when soil water availability increases following precipitation events at the end of the growing season.

Combining thinning and diverse plantings to adapt to climate-change-induced timber supply shortage in British Columbia

Forestry is an important component of Canada’s economy with British Columbia (BC) contributing almost half to the national roundwood production. Yet, the country’s timber supply and forest economy are threatened by climate change, with increased frequency and severity of natural disturbances and changes in forest productivity. Mountain pine beetle ( Dendroctonus ponderosae) outbreaks are endemic in BC, but the latest climate change-driven outbreak has resulted in a cumulative loss of over half of all merchantable pine, leading to a mid-term timber supply shortage. In this study, we investigate the potential of commercial thinning and alternative planting regimes based on species diversification and assisted species migration to mitigate the anticipated decrease in timber supply in BC. We simulated the long-term effects of these management options in a case study area in interior BC, using a toolbox that combines management- and research-oriented data and models. We found that combining commercial thinning and species diversification has the best potential to mitigate future timber supply shortages in BC. We discuss the limits of this toolbox approach and identify research needs and recommendations for future studies aiming at modelling cumulative effects of management, climate change, and natural disturbances on timber supply.

On Comparisons in Map Art

The series of collages created for this issue combines satellite images of the Interior of British Columbia (Sentinel-2 images via Planet Labs) with data visualizations representing land use and agricultural production on a global scale. The collages contrast the optical space of satellite imagery with modernist approaches to form, as disparate aspects of mapping technique. A descriptive text accompanying the series outlines historical context for the process of mapping through aerial surveys in Canada.

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

AbstractWestern 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.

Approaching collaboration in primary care differently: Exploring boundaries and boundary objects.

In recent primary care policy, collaboration is often understood as an outcome, such as the delivery of team-based care or an integrated health system. This outcome-based understanding of collaboration in policy has proven challenging to achieve in practice. This article introduces the concepts of constructing boundaries and boundary objects used in other disciplines, to support our understanding of collaboration by observing the collaborative process. Multiple methods, such as semi-structured interviews, discourse analysis, and member-checking, were used to compare primary care collaborations across three distinct time periods during the onset of COVID-19 within Interior British Columbia. Data analysis revealed the changing nature of boundaries and boundary objects, providing insights into the collaborative process. Through the exploration of boundaries and boundary objects, this article provides a way to approach collaboration in practice differently. By better understanding the process of collaboration, this research could potentially improve collaborative outcomes.

Forest disturbance thresholds on summer low flows in the interior of British Columbia, Canada

Summer low flows are critically important for community water supply and various aquatic functions in the interior of British Columbia (BC), Canada. There is a critical need to determine forest disturbance thresholds on summer low flows, particularly in the context of climate change and increasing forest disturbance. The forest disturbance threshold is defined as the disturbance level above which significant changes in flow variables are detected. In this study, we developed a seasonal hydrological response curve to determine forest disturbance thresholds for significant hydrological impacts on summer low flows in 20 forested watersheds in the BC interior. Based on the proposed method, the results suggest that forest disturbance thresholds varied from 8 to 52 % of CECA (cumulative equivalent clear-cut area) with an average of 18 %, which were not significantly different from thresholds on annual streamflow. Watersheds characterized by more distinct dry summers, lower annual energy availability, higher snow contributions, larger sizes, and greater topographic gradients (represented by greater slope, elevation difference, and downslope distance gradient, and lower water retention index) had lower disturbance thresholds on summer low flows. Both positive (increasing) and negative (decreasing) impacts of forest disturbance on summer low flows were detected. These results can greatly support practical watershed management for sustaining water supply in the local communities. Our methodology can potentially be applied in any individual watershed to assess forest disturbance thresholds on summer low flows where long-term data on forest disturbance, climate, and hydrology are available.

Forest Disturbance Thresholds and Cumulative Hydrological Impacts

AbstractForest 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.

Evapotranspiration and its partitioning during and following a mountain pine beetle infestation of a lodgepole pine stand in the interior of British Columbia, Canada

IntroductionMassive tree mortality events in western Canada due to widespread infestation by mountain pine beetle (MPB) are expected to impact local-to-regional evapotranspiration (ET) dynamics during and after a disturbance. How ecosystem-level ET and its components may vary with canopy-tree mortality (treefall) and subsequent understory recovery remains unclear.MethodsWe used 10 years of continuous eddy-covariance and remote-sensing data (2007–2016) and machine-learning models based on random forest and xgboost to determine forest- and climate-driven effects at temporal scales appropriate for a lodgepole pine-dominated stand following a major, five-year MPB disturbance initiated in the summer of 2006.ResultsTotal annual ET over the 10 years ranged from 207.2 to 384.6 mm, with annual plant transpiration (T) contributing to 57 ± 5.4% (mean ± standard deviation) of annual ET. Annual ET initially declined (2007–2011) and then increased (2011–2016), with ET and T/ET increasing at statistically non-significant rates of approximately 3.2 and 1.2% per year from 2007 to 2016. Air temperature (Ta) and vapor pressure deficit (VPD) were the most important predictors of seasonal variation in ET and T/ET during the 10-year period, with high Ta, VPD, and photosynthetically active radiation (PAR) causing ET and T/ET to increase. Annual ET increased with both increasing spring Ta and decreasing VPD. Annual T/ET was shown to increase with increasing VPD and decrease with increasing volumetric soil water content at a 5-cm depth (VWC5). Enhanced vegetation index (EVI, an indicator of canopy greenness) lagged T and overstory tree mortality, whereas previous- and current-year values of EVI were shown to be poor predictors of annual ET and T/ET.Discussion and conclusionsThese findings suggest that the promotion of climate factors on forest ecosystem-level water vapor fluxes may offset reductions promoted by MPB outbreaks. Climate processes affected water vapor fluxes more than biotic factors, like stand greenness, highlighting the need to include climate-regulatory mechanisms in predictive models of ET dynamics during and subsequent to stand disturbance. Climate and forest-greenness effects on water vapor fluxes need to be explored at even longer time scales, e.g., at decadal scales, to capture long-drawn-out trends associated with stand disturbance and its subsequent recovery.

Understanding nurses' experience of climate change and then climate action in Western Canada.

To understand nurses' personal and professional experiences with the heat dome, drought and forest fires of 2021 and how those events impacted their perspectives on climate action. A naturalistic inquiry using qualitative description. Twelve nurses from the interior of British Columbia, Canada, were interviewed using a semi-structured interview guide. Thematic analysis was employed. No patient or public involvement. Data analysis yielded three themes to describe nurses' perspective on climate change: health impacts; climate action and system influences. These experiences contributed to nurses' beliefs about climate change, how to take climate action in their personal lives and their challenges enacting climate action in their workplace settings. Nurses' challenges with enacting environmentally responsible practices in their workplace highlight the need for engagement throughout institutions in supporting environmentally friendly initiatives. The importance of system-level changes in healthcare institutions for planetary health.

Fuel types misrepresent forest structure and composition in interior British Columbia: a way forward

BackgroundA clear understanding of the connectivity, structure, and composition of wildland fuels is essential for effective wildfire management. However, fuel typing and mapping are challenging owing to a broad diversity of fuel conditions and their spatial and temporal heterogeneity. In Canada, fuel types and potential fire behavior are characterized using the Fire Behavior Prediction (FBP) System, which uses an association approach to categorize vegetation into 16 fuel types based on stand structure and composition. In British Columbia (BC), provincial and national FBP System fuel type maps are derived from remotely sensed forest inventory data and are widely used for wildfire operations, fuel management, and scientific research. Despite their widespread usage, the accuracy and applicability of these fuel type maps have not been formally assessed. To address this knowledge gap, we quantified the agreement between on-site assessments and provincial and national fuel type maps in interior BC.ResultsWe consistently found poor correspondence between field assessment data and both provincial and national fuel types. Mismatches were particularly frequent for (i) dry interior ecosystems, (ii) mixedwood and deciduous fuel types, and (iii) post-harvesting conditions. For 58% of field plots, there was no suitable match to the extant fuel structure and composition. Mismatches were driven by the accuracy and availability of forest inventory data and low applicability of the Canadian FBP System to interior BC fuels.ConclusionsThe fuel typing mismatches we identified can limit scientific research, but also challenge wildfire operations and fuel management decisions. Improving fuel typing accuracy will require a significant effort in fuel inventory data and system upgrades to adequately represent the diversity of extant fuels. To more effectively link conditions to expected fire behavior outcomes, we recommend a fuel classification approach and emphasis on observed fuels and measured fire behavior data for the systems we seek to represent.

Settling in a Mid-sized City in the Interior of British Columbia: A Case Study of Recent Immigrants' Housing Experiences in Kelowna (Central Okanagan Valley)

Abstract: In the past, immigrants and refugees tended to overlook small and mid-sized cities in Canada, but this has changed since the beginning of the 21th century, and the mid-sized city of Kelowna has gradually emerged as a popular destination for newcomers from all over the world. Housing is critical to the resettlement and integration of all immigrants. Recent immigrants, especially renters, face challenges in their settlement and housing experiences, including limited financial resources, language barriers, and rental-housing discrimination based on ethnicity or race, and yet relatively little is known about these experiences and the barriers they encounter in mid-sized cities. This paper explores the settlement and housing experiences of recent immigrants in the city of Kelowna, a mid-sized city in the interior of British Columbia (Canada) with a focus on the rental housing market. The study draws on data from questionnaire surveys administered in 2015 and 2018 with a total of 67 recent immigrant respondents. The findings reveal that immigrant newcomers experienced financial stress and significant challenges in locating affordable rental housing due to high housing costs, low vacancy rates, lack of reliable information, language barriers, and discrimination by landlords based on immigrants' ethnic and racial background. Immigrants are increasingly redefining the social and cultural geography of mid-sized Canadian cities, and there is a need to ensure that they are able to access affordable, adequate, and suitable housing, and ultimately settle into society. This is particularly crucial given the rising cost of living in Canada, the projected increase in immigrant levels for 2023-25, and the importance of immigrant settlement in a post-pandemic context. Résumé: Dans le passé, les immigrants et les réfugiés avaient tendance à négliger les petites et moyennes villes du Canada, mais cela a changé depuis le début du 21e siècle, et la ville de taille moyenne de Kelowna est progressivement devenue une destination populaire pour les nouveaux arrivants du monde entier. Le logement est essentiel à la réinstallation et à l'intégration de tous les immigrants. Les immigrants récents, en particulier les locataires, sont confrontés à des défis dans leur expérience d'installation et de logement, notamment des ressources financières limitées, des barrières linguistiques et une discrimination en matière de location et de logement fondée sur l'ethnicité ou la race, et pourtant on sait relativement peu de choses sur ces expériences et les obstacles qu'ils rencontrent dans les villes de taille moyenne. Cet article explore les expériences d'établissement et de logement des immigrants récents dans la ville de Kelowna, une ville de taille moyenne située à l'intérieur de la Colombie-Britannique (Canada), en mettant l'accent sur le marché du logement locatif. L'étude s'appuie sur des données provenant d'enquêtes par questionnaire menées en 2015 et 2018 auprès d'un total de 67 immigrants récents. Les résultats révèlent que les nouveaux arrivants immigrés ont connu un stress financier et des difficultés importantes pour trouver un logement locatif abordable en raison des coûts élevés du logement, des faibles taux d'inoccupation, du manque d'informations fiables, des barrières linguistiques et de la discrimination des propriétaires fondée sur l'origine ethnique et raciale des immigrés. Les immigrants redéfinissent de plus en plus la géographie sociale et culturelle des villes canadiennes de taille moyenne, et il est nécessaire de veiller à ce qu'ils puissent accéder à un logement abordable, adéquat et adapté, et finalement s'installer dans la société. Cette question est particulièrement cruciale compte tenu de l'augmentation du coût de la vie au Canada, de l'augmentation prévue du nombre d'immigrants pour 2023-25 et de l'importance de l'établissement des immigrants dans un contexte post-pandémique.

Influence of irregular shelterwood treatments on intensity and severity after a large wildfire in lodgepole pine stands: A case study from the interior British Columbia.

Climate change has significantly impacted the wildfire regimes in lodgepole pine forests, resulting in prolonged fire seasons and altered fire behaviour. In North America, fire patterns have shifted towards more frequent and severe wildfires after a century of fire suppression. In response, silviculture practices in fire-prone areas should aim to restore diverse forest structures that are resistant or resilient to wildfires. In Western Canada, where forestry is a key industry, interest in seeking silvicultural solutions for promoting forest resilience to wildfires has increased following the devastating wildfire seasons between 2017 and 2023. Irregular shelterwood, a silvicultural system with a relatively short history of implementation in British Columbia, has been deployed in ecologically sensitive areas to promote structural heterogeneity and meet management goals for biodiversity and wildlife values. Although the impacts of irregular shelterwood on wildlife habitat and abundance have been well studied, the interaction between wildfire and the stand structure created by irregular shelterwood remains poorly understood. To understand the effectiveness of the irregular shelterwood in building wildfire resilience, we present a study of a lodgepole pine stand that was treated with irregular shelterwood and partially burned in a wildfire in 2017. This study collected ground fuel, canopy fuel, and tree data from four stand types (irregular shelterwood treated-burnt, treated-unburnt, untreated-burnt, and untreated-unburnt) and analyzed the difference in char height and fire-induced mortality between burnt and unburnt conditions, with irregular shelterwood treatment being a variable. The results demonstrated reduced wildfire effect in the irregular shelterwood stand in this region of British Columbia. This observation was made at a stage where the openings have not been colonized by regeneration. This case study provides valuable insights into the effectiveness of irregular shelterwood in mitigating wildfire risk, and proposes a potential silviculture solution to promote forest resilience to wildfire.

Population-based study of Morganella-Proteus-Providencia group bloodstream infections.

There is a paucity of studies investigating the population-based epidemiology of Morganella-Proteus-Providencia (MPP) group infections. Our objective was to determine the incidence, risk factors, and outcome of MPP group bloodstream infections (BSI), and explore species-specific differences. Population-based surveillance was conducted in the western interior of British Columbia, Canada, between April 1, 2010 and March 30, 2020. Sixty-two incident MPP group BSI occurred for an annual incidence of 3.4 per 100,000 residents; rates for Morganella morganii, Proteus mirabilis, and Providencia species were 0.5, 2.6, and 0.3 per 100,000 population, respectively. The median year of age was 72.5 and was different (p = 0.03) among the groups. Most (92%) MPP group BSIs were of community-onset. Significant differences were observed in the distribution of clinical focus of infection, with most notably 81% of P. mirabilis BSI due to genitourinary focus as compared to 60% and 22% for Providencia species and M. morganii, respectively. Comorbid illnesses that increased the risk for development of MPP group BSI (incidence rate ratio; 95% CI) were HIV infection (37.0; 4.4-139.6), dementia (11.5; 6.1-20.7), cancer (6.4; 3.2-11.9), stroke 6.5 (2.8-13.3), and diabetes 2.7 (1.3-5.0). Thirteen, one, and none of the cases with P. mirabilis, M. morganii, and Providencia species BSI died within 30 days of index culture for respective all cause case-fatalities of 27%, 11%, and 0% (p = 0.1). Although collectively responsible for a substantial burden of illness, the epidemiology of MPP group BSI varies significantly by species.

Spatially variable effects of streamflow on water temperature and thermal sensitivity within a salmon‐bearing watershed in interior British Columbia, Canada

AbstractWarming temperatures can have negative consequences for aquatic organisms, especially cold‐adapted fishes such as Pacific salmon. The magnitude of warming is related to the thermal sensitivity of streams in salmon‐bearing watersheds (i.e., change in stream temperature for every 1°C increase in air temperature), which can vary based on several factors including streamflow. Management actions to increase streamflow may therefore benefit salmon by decreasing thermal sensitivity. However, the effects of streamflow on thermal sensitivity are often complex, as the temperature of flow inputs can directly increase or decrease temperatures. This study aimed to disentangle the influence of streamflow on thermal sensitivity and stream temperature over 4 years in the Nicola River, a regulated semiarid watershed in south‐central British Columbia, Canada. A statistical modeling approach was used to estimate streamflow effects on stream temperatures and thermal sensitivity (i.e., relationship of regional air temperature to stream temperature) at 12 sites from 2018 to 2021. Streamflow had a variable influence on stream temperatures across the watershed via both direct effects and by modulating thermal sensitivity. At a given site, streamflow was generally negatively associated with summer daily mean stream temperature, but the magnitude of its influence varied among locations and years. The influence of streamflow on thermal sensitivity was also highly variable both spatially and temporally. The analysis suggests that there may be complex relationships between streamflow, stream temperature, and thermal sensitivity, which complicates the efficacy of flow as a lever to mitigate high temperatures in regulated systems.

The seasonal movement of sediment-associated marine-derived nutrients in a morphologically diverse riverbed: the influence of salmon in an Interior British Columbia river

PurposeThis study (1) investigated the extent to which flocculation and the hydrological and morphological attributes of an interior salmon-bearing river regulate the seasonal storage of marine-derived nutrients (MDN) and (2) compared the contribution of MDN to the fine bed sediment relative to other nutrient sources to the river.MethodsPrevious research has determined that the co-existence of re-suspended fine sediment, generated by salmon redd construction, with salmonid excretion and decay products in the water column creates ideal conditions for the flocculation of these inorganic and organic particles. Stored and suspended fine bed sediment was sampled from seven sites with varying morphologies and bed substrate down the length of a large spawning river in the interior of British Columbia over a 12-month period. MDN contributions to the sediment was tracked using aggregated versus dispersed particle size, carbon-to-nitrogen ratios, stable carbon and nitrogen isotopes, and MixSIAR modeling.Results and discussion(1) There was a significant longitudinal spatial distinction of nutrient retention between sites upstream and downstream of a large seasonally inundated floodplain; (2) the MDN isotopic signal in the surficial stored bed sediment in this sample year was short term; and (3) upstream spawner numbers, substrate size, stream morphology, and discharge were relevant to both the magnitude and retention time of sediment-associated MDN.ConclusionA cumulative magnification of MDN was correlated with the distance from the headwaters and the number of upstream spawners. The relationship between MDN retention in interior rivers, and possible multi-year accumulation, was influenced by variability in channel morphology, substrate size, and the presence of an inundated floodplain halfway down the river.

Climate-mediated lodgepole pine tree growth response to thinning and fertilization in interior British Columbia

In the interior British Columbia, forest managers use thinning to reduce inter-tree competition and soil fertilization to enhance the soil nutrient status for improved tree growth. In recent decades, thinning has been promoted as a tool to increase tree resilience to drought. However, fertilization may modulate tree response to drought by altering biomass allocation from below- to above-ground depending on soil moisture availability. Here, we analyzed two long-term thinning and fertilization trials set up in fire-origin lodgepole pine (Pinus contorta Douglas ex Loudon) stands in two biogeoclimatic subzones in interior British Columbia that differ in soil productivity. Both trials featured untreated control, fertilized-only, thinned-only, and the combination of thinning and fertilization treatments. Drought Index (i.e., Standardized Precipitation Evapotranspiration Index, SPEI) was estimated for each site and used as a covariate in a linear mixed effects model to assess the impacts of thinning and fertilization on tree growth sensitivity to drought. Tree growth was increased by fertilization at the very dry-cold site, and more so in the thinned plot than the unthinned plot. The opposite effect of thinning on tree growth was found at the dry-cold relatively fertilized site. Tree growth was less sensitive to drought in the thinned-only plots at both sites. Our results, however, showed increased tree growth sensitivity to drought under the thinning and fertilization combination treatment at the less dry and relatively more productive site. The results suggest that the combination of thinning and fertilization can increase tree growth on very dry-cold and dry-cold sites and may be a suitable strategy to mitigate drought stress on tree productivity.

Winner and losers: examining biotic interactions in forbs and grasses in response to changes in water and temperature in a semi-arid grassland.

Warming and changing water amount can alter the outcome of biotic interactions in native and exotic plants between facilitation and competition. Exotic plants may adapt better to changing environmental conditions, such that they may compete better than native plants. We conducted competition trials for four plant species, two exotic forbs (Centaurea stoebe and Linaria vulgaris) and two grasses (exotic Poa compressa and native Pseudoroegneria spicata), commonly found in Southern interior British Columbia. We compared the effects of warming and changing water on target plant shoot and root biomass, and on pair-wise competitive interactions among all four species. We quantified interactions using the Relative Interaction Intensity index, which has values from -1 (complete competition) to +1 (complete facilitation). C. stoebe biomass was highest under low water and no competition. Facilitation of C. stoebe was found under high water and low temperatures but shifted to competition under low water and/or warming. Competition in L. vulgaris decreased due to reduced water and increased due to warming. Grasses were less competitively suppressed by warming but more competitively suppressed by reduced water input. The response of exotic plants to climate change can differ by plant species, moving in opposite directions for both forbs, but grasses appear to respond similarly. This has consequences for grasses and exotic plants in semi-arid grasslands.

Approaches to Bio-Cultural Diversity in British Columbia

This paper highlights an action research project into some decolonizing practices for environmental learning in the Canadian context of the British Columbia (BC) curriculum through case study and focus groups with Indigenous educators. A key finding taken from these discussions is that educators must strive to learn with Indigenous people not about them as the process of decolonization is about acknowledging multiple knowledge and value systems. We hosted two consultations with groups of Indigenous knowledge holders in the process of our work. The first consisted of a purposeful sample of Indigenous educators and academics drawn from Coast Salish communities in and around urban regions in coastal British Columbia (N = 20), the second draws on a purposeful sample of rural Indigenous educators and academics drawn from the Okanagan valley and British Columbia Interior (N = 10). The vignettes we share focus on how educational policy can be infused with Indigenous knowledges and pedagogical perspectives and, respectively, how policy changes might inform instruction on climate change education and a variety of other environmental topics. The revised framework we produce will guide teachers in their educational planning and support the implementation of environmental learning in diverse subjects using the dual lenses of bio-cultural diversity and inquiry—teaching about the environment and Indigenous knowledges together as an organizing theme for all teaching and learning. Our work highlights key aspects of our research involving practicing teachers, academics, provincial Ministries of Education and Environment as well as the Canadian Commission for UNESCO. The research articulates several important bridge-building activities: one linking research and policy, one bridging theory with practice, and most importantly, one bridging the inherent synergies among Indigenous and environmental knowledges.

Wildfire disturbance reveals evidence of ecosystem resilience and precariousness in a forest–grassland mosaic

AbstractForest and grassland ecosystems are sometimes located adjacently within the same climate. In Interior British Columbia, Canada, there are complex forest–grassland mosaics within the Interior Douglas‐fir biogeoclimatic zone. Historically, both grassland and forest ecosystems experienced high‐frequency, low‐severity fire regimes. Since European settlement and introduction of livestock grazing and fire exclusion, trees have encroached on grasslands, and tree densities in forests have increased. In this study, we characterize plant communities and near‐surface soil moisture in forest and grassland sites, and in historical grassland sites affected by tree encroachment. We hypothesized that spatial and temporal patterns of near‐surface soil moisture are reflected in aboveground plant community composition and structure. After initial sampling of soil moisture and plant communities, the study area was burned in a wildfire. Applying a multifactorial approach to comparing adjacent grassland and forest sites, we treated the wildfire event as a natural experiment, sampling post‐wildfire plant species composition and soil moisture, and measuring the severity and spatial heterogeneity of surface burn conditions. Evidence supports the concept of mutually exclusive fire‐reinforced bistable grassland and forest states, with greater spatial heterogeneity of soil moisture and burn severity in forests, and highly uniform patterns of soil moisture, vegetation, and burn severity in grasslands. Areas of forest encroachment on grasslands had understory plant communities dominated by exotic species, while restored grasslands had native bunchgrass cover like typical grasslands of the region. Additionally, there was post‐wildfire divergence of forest‐ and grassland‐associated plant communities. Viewed through a resilience theory conceptual framework, we suggest that ecosystem legacies are reinforcing post‐wildfire ecosystem identity and associated native plant communities. External factors—particularly past heavy livestock grazing and fire suppression—have caused ecosystem precariousness that can be addressed with management actions.