Climatology

Our forests are undergoing significant changes due to climate-induced challenges such as wildfires, droughts, and insect outbreaks.

Climatology research is advancing strategies such as the assisted migration of tree species and adaptive forest management techniques to enhance ecosystem resilience, preserve biodiversity, and maintain their role as vital carbon sinks. 

Climate and Microclimate at the Boreal Inga Lake Site Preparation Study (1988‒2020), and Selected White Spruce (Picea glauca) Responses - EN 125

From 1988 to 2020, climate and microclimate data were collected at the Inga Lake site preparation study. The results, along with a detailed description of associated metadata, have been reported in an unpublished file report.1 This Extension Note is intended to inform readers about the existence of the file report and how to access it, and to briefly describe selected results. Of primary interest, air temperature and precipitation data collected at the research site and nearby weather stations provided evidence of climate change in the geographic area. Both summer maximum and winter extreme minimum air temperatures suggest warming conditions; minimum air temperatures no longer commonly reach −40°C, and decadal means for winter extreme minimum temperature have become warmer. The frequency and severity of growing-season drought also increased during the decade ending in 2017 compared with the three preceding decades. Spruce height growth was abnormally poor in 2014 and 2016, and we speculate that a combination of drought and unseasonably warm winter to early spring temperatures may have been responsible.

Applying Climate Change Information in Resource Management User Needs Survey - TR126

Climate change information, with estimates of natural disturbance and projected ecosystem shifts, can support research and inform decision-making for a wide range of values within the purview of the British Columbia Ministry of Forests, Lands, Natural Resource Operations and Rural Development. In recent workshops, a need for Ministry-supported climate projections was identified. Evaluating how users apply climate projections should guide content; understanding their skills can help in designing effective delivery and support. We built a survey to solicit information on climate data needs and applications, preferred delivery of information, and respondents’ skills. Between November 2018 and February 2019, we collated 45 responses from Ministry staff who were working in a variety of areas, including ecology, fisheries and wildlife, forestry, aquaculture, hazards, water stewardship, land permitting, planning, and engineering.

Development of a Drought Risk Assessment Tool for British Columbia Forests Using a Stand-level Water-balance Approach - TR125

We used an annual water-balance approach to assess the relative risk of current and future drought-induced stress and mortality at the stand level for tree species in British Columbia, Canada. The aim was to develop a drought risk–mapping tool that can be used by forest managers to inform harvest and silvicultural decisions at the stand level. We used the concept of absolute soil moisture regime (ASMR), which equates to the ratio of actual evapotranspiration (AET) to potential evapotranspiration (PET), to compare estimates of ASMR class based on expert opinion with ASMR class calculated by a waterbalance equation using long-term climate data and reference site and soil conditions for different site types. The quantitative estimates of ASMR class generally agreed with those based on expert opinion. 

Climate and Its Relevance to Lodgepole Pine Performance at the Sub-Boreal Bednesti Research Site over a 30-year Period - TR121

The Bednesti site preparation study, located in the SBSdw3 biogeoclimatic variant of central British Columbia, examined lodgepole pine response to various types of site preparation from 1988–2017. In addition to tree measurements, climate and microclimate data were collected to characterize important environmental parameters such as air temperature, soil temperature, soil moisture, precipitation, and solar radiation that could assist with the interpretation of pine survival and growth responses. Although various publications have sometimes referred to the climate and microclimate data to help interpret specific tree or vegetation responses, no single publication has focussed on the environmental data or comprehensively examined possible correlations with tree growth. Although it is difficult to draw firm conclusions regarding such relationships due to limited replication of some of the climate and microclimate measurements, trends can be identified that suggest avenues for further research.

Long-term Daily Air Temperature and Precipitation Record for the Lake Cowichan Area - TR112

Daily air temperature and total precipitation data have been collected in the Cowichan River valley for more than 100 years as part of Environment and Climate Change Canada’s monitoring network. However, none of the weather stations have operated continuously for the whole period. This report describes combining station records to create a continuous daily maximum and minimum air temperature and total precipitation record from March 1901 to December 2016 for the Cowichan Lake Forestry (CLF) station (48°50' N 124°08', 177 m). Linear regressions were fitted to daily and monthly data for records that overlapped between CLF and other stations to generate coefficients to adjust a station to CLF. The coefficients of determination (adjusted R2 ) ranged from 0.85 to 0.99 for temperature and from 0.58 to 0.99 for precipitation. Standard error of the estimate for daily temperatures ranged from 0.9 to 2.1°C and from 3 to 8 mm for precipitation; the larger values were for stations distant from CLF. The monthly record compared well to the Shawnigan Lake record from the Adjusted and Homogenized Canadian Climate Data base. The daily record was used to calculate trends for a range of variables from 1902 to 2016 and from 1951 to 2016. Trends in annual and seasonal temperature indicated a rise of 0.1–0.3°C per decade and were significant at the 99.9% level. Precipitation trends were small and most were not significant at the 90% level.

A Stand-Level Drought Risk Assessment Tool for Considering Climate Change in Forest Management - EN119

Increased drought, caused by recent regional warming, is believed to be one of the leading causes of tree mortality in forest ecosystems of western North America (Van Mantgem and Stephenson 2007) and worldwide (McDowell et al. 2008; Allen et al. 2010). Changes in tree species distributions as a response to climate change have been examined at a broad level in British Columbia (e.g., Hamann and Wang 2006), but the varied response of individual tree species at the stand level to differing site properties, such as soil moisture regime, is needed to inform standlevel management. From 2009 to 2013, a Drought Risk Analysis and Decision Support Tool was developed by B.C. Ministry of Forests, Lands and Natural Resource Operations (flnro) researchers and was funded by the Future Forest Ecosystem Science  Council, Project b5 (www2 .gov.bc.ca/gov/content/environment/ natural-resource-stewardship/ natural-resources-climate-change/ natural-resources-climate-change -applied-science). The project focussed on predicting soil moisture availability at the site level in response to climate change, and resulted in the development of the  Stand-Level Drought Risk Assessment Tool. 

A Proposed Climate-based Seed Transfer System for British Columbia - TR99

A well-designed seedlot selection system is central to the maintenance of healthy and productive forest plantations, particularly in an era of rapidly changing climates. Opportunities for improving the effectiveness and efficiency of seedlot selection in British Columbia are provided by new technologies, analysis techniques, and genetic data. We propose a climate-based system of seed transfer that is expected to better match seedlots to planting sites using new transfer functions to identify biogeoclimatic ecosystem classification units where each seedlot is anticipated to grow well. The system also: (1) facilitates the use of assisted migration to reduce climate change impacts to forest health and productivity; (2) allows for wider seedlot deployability; (3) increases ease of use; (4) simplifies system updating; (5) quantifies adaptation of seed source options to improve seed source deployment; and (6) integrates with species selection.

Climate Patterns, Trends, and Projections for the Omineca, Skeena, and Northeast Natural Resource Regions, British Columbia - TR97

This document summarizes baseline climate, trends, and projections for the three natural resource regions within the North Area of the British Columbia Ministry of Forests, Lands and Natural Resource Operations (FLNRO): the Omineca, Skeena, and Northeast Natural Resource Regions. This information is intended to support the goals outlined in FLNRO’s Climate Change Strategy (www.for.gov.bc.ca/het/climate/strategy/index.htm) and to aid in climate change action and adaptation planning for regions and districts within the North Area. Region and district baseline climate summaries were created using daily recorded data from Environment Canada weather stations from the time weather station recording began in 1886 up to 2008 (Figure 1). Climatic projections for the base climate stations were developed using the ClimateBC spatial software (Wang et al. 2012).

Microclimate Studies in Mountain Pine Beetle–Damaged Silvicultural Systems on the Chilcotin Plateau: The Itcha-Ilgachuz Project (1997–2013) - TR89

A long-term study on group selection and irregular group shelterwood silvicultural systems began in 1994 to determine their effectiveness in managing habitat for woodland caribou (Rangifer tarandus caribou). The systems are being applied in the very dry, cold Sub-Boreal Pine Spruce (SBPSxc) and the very dry, very cold Montane Spruce (MSxv) biogeoclimatic subzones located on the high-elevation Chilcotin Plateau in west-central British Columbia. Microclimate was monitored in paired partial cut and clearcut treatments in three study blocks over a range of elevations. In these harsh growing environments, partial cutting strongly influenced the air and soil temperature, frost events, and snow-free date. As the microclimate variables changed over the 16-year study period, so did vegetation layers in the partial cuts and clearcuts. In addition, an outbreak of the mountain pine beetle (Dendroctonus ponderosae) killed 61% of the mature trees in the partial cut treatments during the middle part of this study (2003–2008) and this mortality and subsequent degeneration of the trees could be affecting the microclimate.

Enhancing Provincial Climate Monitoring: the Forest Ecosystem Research Network and the Climate Related Monitoring Program - EN111

The Research Program within the Ministry of Forests, Lands and Natural Resource Operations (FLNRO) recognizes that environmental monitoring and research is vital to sound natural resource science and management. Many of the research scientists within FLNRO have installed weather stations to support their research, some of which have climate records spanning multiple decades. Recognizing that these climate data are useful to the larger scientific and operational community, FLNRO research joined the Climate Related Monitoring Program (CRMP) in 2009. The CRMP, initiated and led by the Ministry of Environment, was formed to build a strong foundation of climate knowledge to address British Columbia’s Climate Action Plan (www.env.gov. bc.ca/cas/programs.html). The CRMP has a mandate to make long-term meteorological data available for climate change analysis and adaptation through an agreement with the Pacific Climate Impacts Consortium. 

Microclimate Studies in Uniform Shelterwood Systems in the Sub‑Boreal Spruce Zone of Central British Columbia - TR57

In the Sub-Boreal Spruce dry warm (SBSdw) biogeoclimatic subzone, on the Interior Plateau of British Columbia, frost is a limiting factor for the establishment and growth of Douglas-fir (Pseudotsuga menziesii). A research trial, using a uniform shelterwood silvicultural system, was harvested in 1991, then again in 2001, to test how residual basal area retention affected regeneration establishment, growth, and condition. Microclimate stations were installed in two of the residual basal area treatments (15 m²/ha and 20m²/ha) to measure frost events. From 2001 to 2008, near-ground air and soil temperatures were monitored on two pairs of adjacent 20m²/ha and 15 m²/ha treatments along with one additional replicate of the 20m²/ha treatment, and a clearcut.

Minimum air temperatures and total duration (minutes) of air temperatures below 0°C were compared between treatments during the bud flush (15 May-31 July) and bud set (15 August-30 September) seasons. The clearcut treatment had a much longer duration of subfreezing minutes than the forested treatments for both bud flush and bud set periods, as well as a greater number of frosts and lower extreme minimum temperatures. Differences between the 15 and 20m²/ha treatments were not as great; however, both 15 m²/ha treatments had longer duration of subfreezing minutes and increased numbers of frosts compared to the 20m²/ha treatments. The sky view factor increased as basal area decreased, and was positively correlated with the duration of subfreezing minutes. There were few significant frost events during the June to mid-August period in the forested treatments over the 7-year study. The data suggest that residual basal areas of 15 m²/ha or greater provide adequate frost protection for regeneration.

Climate Change Adaptation: Potential Contributions of Red Alder in Coastal British Columbia - TR74

The red alder resource in British Columbia has the potential to support a future hardwood manufacturing sector over 10 times larger and considerably more diverse than the current condition. Three quarters of this increase is possible simply by managing the existing red alder resource to an intensity similar to that for conifers, with the remainder of the increase relying on climate change adaptation to take advantage of potentially improved future growing conditions. Increased harvest rates would provide the Province with commensurate social benefits in terms of jobs, taxes, and royalties. Additional benefits of increased management attention would be realized through improved ecosystem resiliency and the contributions that red alder makes to a wide variety of ecosystem services.

Assisted Migration to Address Climate Change in British Columbia Recommendations for Interim Seed Transfer Standards - TR48

Climate change is expected to result in trees in most regions of British Columbia becoming increasingly maladapted to the climates in which they are planted. Consequently, planting seedlings adapted to future climates (assisted migration) is recognized as a key strategy to address climate change, as it will help maintain healthy, productive forests, and ensure capture of gains obtained from decades of selective breeding. To examine opportunities to incorporate assisted migration into British Columbia’s seed transfer system, the feasibility of increasing the upper elevational transfer limit of British Columbia’s Class A and Class B seed was assessed by calculating the climatic transfer distance associated with elevational transfers. A rationale was developed for quantifying an appropriate climatic distance and range to migrate seed, and was used to evaluate elevational transfer increases of 100 and 200 m.

Climate Change, Impacts, and Adaptation Scenarios: Climate Change and Forest and Range Management in British Columbia - TR45

The Fourth Assessment Report of the Intergovernmental Panel on Climate Change states that warming of the climate system is unequivocal. It notes with a very high level of confidence that much of this warming is due to human activities through the release of greenhouse gases. The continued increase in greenhouse gas concentration over the next century could result in an increase in global mean annual temperatures by up to 4°C and changes in precipitation regimes. The rate of warming will be faster than has occurred in the past and there will be an increase in the frequency and intensity of extreme temperature and precipitation events. British Columbia will have greater warming and changes in the precipitation regime than the global average. All models and emissions scenarios predict an increase in winter and summer temperature. Warming would be greater in northern British Columbia than in southern British Columbia and larger in the winter than in the summer, particularly in the winter minimum temperature. Warming is least in coastal areas where it is moderated by the oceans.

A Summary of Climate Change Effects on Watershed Hydrology - EN87

The climate of British Columbia is changing, and with these changes will come many adjustments in watershed hydrology and, ultimately, in the use of water-related resources. Yet, because British Columbia is hydrologically diverse, the local responses to these anticipated changes will differ. Historical Trends in Temperature and Precipitation Analysis of British Columbia climate data for the last 100 years indicates an overall rise in air temperatures for all seasons, with the greatest warming occurring in the winter. This warming has been greater in northern British Columbia than in the southern and coastal regions. Trends in annual precipitation across British Columbia for the last century are more varied than for temperature. The increase in average annual precipitation is more spatially varied than for temperature, with larger increases occurring in regions with comparatively low annual precipitation. During the last 50 years there has been an increase in the occurrence of extreme wet and extreme dry conditions in the summer and a decrease in winter snowpack.

Microclimate Studies in Silvicultural Systems on the Chilcotin Plateau of British Columbia: The Itcha-Ilgachuz Project (1997-2003) - TR22

Group selection and irregular group shelterwood silvicultural systems are being tested as options to conserve woodland caribou (Rangifer tarandus caribou) habitat. If successful, the systems will be applied within the very dry, cold Sub-Boreal Pine-Spruce (SBPSxc) and very dry, very cold Montane Spruce (MSxv) biogeoclimatic subzones, located on the high-elevation Chilcotin Plateau of west-central British Columbia. In these harsh growing environments, partial cutting strongly influences the microclimate in terms of air and soil temperature, frost events, and snow-free dates.

To examine the magnitude of this influence, three pairs of climate stations were set up in partial cuts and clearcuts, across a range of elevations, to compare microclimate conditions. Over the 7-year sample period, all blocks had frequent and sometimes severe (air temperature <-4°C) frosts throughout the growing season. As many as 58 frosts (<0°C) out of 76 nights during the period 1 June-15 August were recorded at one block. Minimum air temperatures of -12.4°C in June and -10.5°C in July were recorded. Partial cuts substantially reduced the number and severity of frosts over clearcuts; however, soil temperature and soil temperature index (ST1) were lower in partial cuts than the nearby clearcuts. Mean growing-season (15 cm) soil temperatures were less than 10°C at all locations, with clearcuts being 1.5-1.9°C warmer than nearby partial cuts. Snow-free dates were approximately 1 month later at the highest-elevation site (1620 m) in comparison to the lowest site (1290 m). This lowered soil temperatures and shortened growing seasons at the highest site. Heavier snowpacks virtually eliminated soil freezing at the highest site.

The study also compared north edge, centre, and south edge microsites within one 30-m opening on each of three partial cuts. The north edge (south aspect) was the most favourable microsite for seedling growth in the partial cuts, with the highest soil temperatures, earlier snow-free dates, and more solar irradiance. Low soil temperatures and light levels made the south edge (north aspect) the least favourable microsite.