Using Harvest and Cumulative Land Use Effects Simulators to Predict Population Change in Canada Warblers

Decision support tools can be used to better understand and manage the cumulative effects of human activities on environmental values in landscapes. This includes protecting species at risk as part of sustainable forest management planning.

One application of decision support tools to support forest management is to improve understanding of potential impacts to one species of concern when managing for the needs of another. Management of forest harvesting to maintain sufficient habitat for Woodland Caribou by deferring logging in caribou range is one example of this^[1,2,3]. A caribou-centric harvest strategy has the potential to transfer harvest pressure to other areas that are important habitats for other threatened species. Understanding trade-offs in management decisions for caribou is an important issue in northern Alberta.

A second application of decision support tools to support forest management planning is accounting for cumulative effects of human and natural disturbances, other than forestry activities, on environmental values in the boreal forest. Given uncertainty about development plans for other industrial sectors or future wildfire rates as a result of climate change, tools that simulate and incorporate multiple land uses and natural disturbance can be used predict effects on species at risk under a range of possible futures^[4,5].

Two harvest planning and land use simulation tools—Patchworks and ALCES Online—have the potential to facilitate both multi-species conservation planning and planning for multiple disturbances in managed landscapes like the Al-Pac FMA area. To demonstrate their utility for land use planning, Patchworks and ALCES Online were used to assess the sensitivity of Canada Warblers in the Al-Pac FMA area to:

• harvest plans designed to maintain habitat for Woodland Caribou, and
• cumulative effects of forestry, other industrial activities, and natural disturbance.

Purpose: In addition to forest harvesting, natural disturbance and energy sector development also affect forest age and the habitat available to different species over time. To project how Canada Warbler populations were affected by cumulative effects of disturbance, we developed five scenarios using the ALCES Online planning tool in which available habitat was affected by forest harvesting, fire, energy development, and seismic line reclamation over a 50-year time span. All scenarios share the same extent and locations of harvest disturbances, and unless otherwise specified, the same burn rate of 284.8 km²/year. 

Scenario 1: “Al-Pac Business as Usual (BAU)” Scenario. Under this scenario, it is assumed that in addition to forestry, some forest habitat is either set back by fire or converted to other land uses such as energy sector development as well as agriculture and urbanization. Specific details include:

• Forest harvesting with 20-year deferral in caribou range,
• Some forest set back by fire at a burn rate of 284.8 km²/year,
• Moderate development of energy sector, settlement, and roads.
• There is no forest regeneration along seismic lines.

Scenario 2: “Seismic Reclamation” Scenario. In this scenario, we assume the same amount and location of fire, harvest, and non-forestry footprint as in the “Al-Pac Business as Usual” scenario, but also assume that seismic lines are successfully reclaimed and start regenerating to forests for Woodland Caribou habitat.  

Scenario 3: “No Fire” Scenario. In this scenario, we assume that no future forests are burned, but other variables are the same as in the “Al-Pac Business as Usual” scenario.

Scenario 4: “No Energy” Scenario. The “No Energy” scenario assumes that no new energy sector development occurs, but other variables are the same as in “Al-Pac BAU”.

Scenario 5: “ Increased Fire” Scenario. The “Increased Fire” scenario assumes that twice the area of forest is burned each decade reducing the area of older forests, but other variables are the same as in “Al-Pac BAU”.

Key Findings: When we considered cumulative effects of harvest, fire, and habitat conversion by non-forestry footprint, Canada Warblers were still projected to increase under all five scenarios we tested. But there were differences between scenarios:

• Canada Warblers showed the strongest response to the “No Fire” scenario increasing by 104% followed by the “No Energy” Scenario in which Canada Warblers increased by 77%
• Canada Warbler increased by 50% if seismic lines are restored (“Seismic Line Reclamation” scenario), and 42% in the “Al-Pac Business as Usual” Scenario, 
• The smallest predicted increase for Canada Warblers was under the “Increased Fire” scenario (+14%).

Management Implications: We found that fire and future energy sector development in addition to forestry reduced habitat for Canada Warbler—a species associated with old deciduous and mixedwood forests—in the Al-Pac FMA area. Projected increases in fire activity reduces the availability of old forest habitat resulting in detrimental impacts to old forest birds like the Canada Warbler^[6]. However, restoring habitat for Woodland Caribou may incidentally have positive effects for Canada Warbler^[7,8]. Seismic reclamation is one strategy being explored for improving Woodland Caribou habitat.