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BEC & Climate Change

BC’s ecosystem classification and Climate Change – The Big Picture

The climate is changing. What happens to BEC?

BC’s ecosystem classification and Climate Change

The Big Picture

As climate has an overarching influence on vegetation, a changing climate (CC) will affect species distributions and suitability in current ranges. So how will Biogeoclimatic Ecosystem Classification (BEC), which uses vegetation communities in its system, remain useful in this changing environment?

Background

Whatever the future climate, land managers will remain interested in understanding “what grows where and how well” to properly manage the diversity of ecosystems and ecosystem services within BC. BEC provides a framework that integrates the essential ecosystem components required for this understanding and will remain essential under CC.
The current BEC database and classification provides immense value as a baseline ecological condition to assess the affects of climate change not only provincially but globally. The maps, classification, and underlying data for the classification represent the best information available to make a realistic assessment of possible future ecosystem change. The program continues to work towards improving current BEC zonation and classifications to provide the best baseline information possible.
Impacts of CC will not be rapid enough to make BEC irrelevant in the near future. Application of the classification, in its current form, for identifying site quality and current climatic zonation will remain valid for at least several decades allowing time for a considered adjustment of the BEC.
Climate change modeling is only hypothetical prediction – the actual future climate is unknown. Management regimes and the classification will need to take a risk management approach to account for many possible future climates.

BEC System

The site component of BEC is an “enduring feature” that will remain stable in climate change. The BEC approach to assessment of site potential will remain valid with any climate change scenario.
Current BEC vegetation assemblages will remain applicable for identifying site quality and current BEC for at least several decades. Vegetation will continue to reflect site conditions even with climate change but specific indicators used may have to evolve with time.

Ongoing research

Modeling ecosystem change under climate change scenarios using BEC and BEC data is currently underway both inside and outside the program. The projection of future climate zones and vegetation changes will be an ongoing task facilitated by modeling and direct measurement of change.
The program is assessing areas and ecosystems most sensitive to changing climate with the intent of installing permanent plots for observing changes with time to inform changes to BEC

The climate is changing. What happens to BEC?

The earth has warmed by about 0.6 °C in the past 100 years, with the largest increase occurring over the last 30 years. Climate change (CC) modeling suggests that a warming of 3 to 6°C may occur in British Columbia over the next 100 years. As climate has an overarching influence on vegetation, a changing climate will affect species distributions and site suitability in current ranges. So how will Biogeoclimatic Ecosystem Classification (BEC) which uses vegetation communities in its system, remain useful in this changing environment?

The short answer is outlined below.

The BEC Framework and Climate Change

Biogeoclimatic ecosystem classification is a framework for understanding the important components of terrestrial ecological systems. These components include climate, site factors, and associated vegetation.
The classification is a tool for reducing complexity and organizing and communicating ecological knowledge between users.
BEC has two spatial scales of focus. The site component addresses environment drivers at a local scale to differentiate relative site quality. And a zonal or climatic component describes and maps regional bioclimates.
The BEC system is primarily interested in differentiating site potential to grow vegetation (species composition, biomass, etc) between different local sites and between different bioclimate regions.

Whatever the future climate, land managers will remain interested in understanding “what grows where and how well” to properly manage the diversity of ecosystems and ecosystem services within BC. BEC provides a framework that integrates the essential ecosystem components required for this understanding.

The Climate Component in a changing climate

Lack of climate stations capable of documenting the complexity of BCs climate, as well as a need to have biologically relevant climate zonation for understanding climatic affects on vegetation and associated sites drove the creation of the climate component of BEC.
BEC zonal units represent bioclimate envelopes that express a long-term sum of inter-annual climate variation expressed as distinct regional vegetation.
The inherent climate variability encapsulated in current BGC units suggests that forests are somewhat resilient to change. It seems likely that application of the current vegetation expression of BGC units will not change for the moderate term (decades).

Current BGC units provide the best baseline data and framework for projecting climate change effects on regional vegetation in BC. Climate change projections can model current bioclimate envelopes under future climate scenarios to assess how regional vegetation may change ¹.

The Site Component in a changing climate

The site component of BEC is defines an ecologically relevant composite of physical site properties including soil, terrain, and site properties such as slope position and aspect.
Assessment of site quality for vegetation is the intent of the site component.
The site component is an “enduring” feature relatively stable with climate change.
The site component of BEC derives relative soil moisture and nutrient regime.
The relative relationship between sites at a local scale will remain stable into the future. E.g. drier, mesic, and wetter sites will retain their relative position and designation in the landscape. Therefore existing ecosystem maps will retain their value into the future for identifying site quality.

The BEC approach to assessment of site potential and will remain valid with climate change.

Vegetation Component in a changing climate

The BEC system uses vegetation communities to assist in the identification of site potential and as an indicator of climate.
Climate change will affect vegetation. Plant species will respond differentially, natural disturbance regimes may change, and insect- and pathogen-host dynamics will change.
Current vegetation assemblages will continue to reflect current climate in the medium term.
Even when climate change impacts are well advanced, vegetation will still indicate site quality but there may be a change in the species involved. Many of the common indicators of site conditions have a wide distribution in the province and will remain useful as indicators but new species or other vegetation evidence may gain importance.
How and when BGC areas will transform with climate change is the focus of current modeling projects. The magnitude of effect will depend on actual climate change, climatic region, and ecosystem resilience.
The dataset underpinning BEC represents the most geographically complete information source for species and ecosystem distributions in the province.

When will climate change affect BEC?

The site component of BEC will remain robust with climate change.
There will be a lag between climate change and vegetation response. It is expected that current vegetation indicators in BEC will be useable in the medium term for assessing site quality and bioclimates. Vegetation will still be useful to indicate site condition even in the long term after climate change effects have become pronounced.
The structure of the BEC framework will still be relevant as climates change beyond the variation of present bioclimates.
Climate change modeling is only hypothetical prediction – the actual future climate is unknown. Management regimes and the classification will need to take a risk management approach to account for many possible future climates.

What is the BEC program doing to address Climate Change

The current BEC database and classification provides immense value as a baseline ecological condition to assess the affects of climate change not only provincially but globally. The maps, classification, and underlying data for the classification represent some of the best information available to make a realistic assessment of possible future ecosystem change. The program continues to work towards improving current BEC zonation and classifications to provide the best baseline information possible.
Application of the classification, in its current form, for identifying site quality and current climatic zonation should remain valid for several decades allowing time for a considered adjustment of the system.
Future site description materials will provide more emphasis on site features of ecosystems.
Modeling ecosystem change under climate model scenarios is currently underway. The projection of future climate zones and vegetation change will be an ongoing task facilitated by modeling and direct measurement of change.
The program is assessing areas and ecosystems most sensitive to changing climate with the intent of installing permanent plots for observing changes with time.
Monitoring ecosystem change over the next decades will improve our understanding of the resilience of ecosystems to ongoing climate change and inform changes to the classification

However the future climate changes, the BC Forest Service will require an ecological framework to understand and manage the diversity of ecosystems within BC. The BEC program is taking steps to ensure that the system will remain robust and useful in an uncertain climatic future.

1. Hamann, A., and T.L. Wang. 2006. Potential effects of climate change on tree species and ecosystem distribution in British Columbia . Ecology 87:2773-2786.

Forest Service British Columbia - Research Branch

Biogeoclimatic Ecosystem Classification Program (BEC)