Close Window

Forest change at the southern limits of the boreal zone

Elizabeth Campbell, Natural Resources Canada, elizabeth.campbell@canada.ca (Presenter)
Joseph Antos, University of British Columbia, jantos@uvic.ca
Tongli Wang, Universitiy of British Columbia, tongli.wang@ubc.ca
Lara VanAkker, Natural Resources Canada, lara.vanakker@canada.ca

Altered disturbance regimes due to climate change will be important drivers of projected ecosystem shifts at the southern limits of the boreal zone. We are using field data and models to characterize forest responses to intensifying or novel bark beetle disturbances, and other effects of continued climate change. To assess boreal forest resilience to a severe spruce beetle (Dendroctonus rufipennis) outbreak in the southern Yukon (1994-2005), we sampled 21 stands dominated by white spruce (Picea glauca) in 2000, 2010 and 2016. In each stand, we collected data on tree species composition, tree size structure, radial growth, and site/soil conditions. We found that the impact of the spruce beetle outbreak varied considerably among stands, reducing tree density (stems/ha) and basal area (m2/ha) between 5 to 85% from 2000 to 2010. Deciduous tree species abundance increased significantly in only 3 stands. Radial growth increment (mm/yr) of nearly half of the surviving canopy (43%) and subcanopy (45%) spruce trees increased by at least 50% since the last re-measurement in 2016. Advanced regeneration of spruce (30-130 cm tall) was abundant but only a small percentage (19%) had increased growth after beetle-caused canopy removal. Despite abundant regeneration and increases in growth among some trees, canopy tree basal area and density reached pre-outbreak values in only 4 of the 21 stands 10 years after the outbreak. More time is needed for these forests to recover. Our models of climate suitability for spruce and spruce-dominated ecosystems, suggest warming temperatures could ─ in the absence of other disturbances ─ favour accelerated forest recovery until about 2055 but after that, the climatic habitats for spruce and boreal forest become very unsuitable. We continue our exploration of climate change effects in these forests using modular landscape simulation modelling approaches.

Poster Location ID: 78

Session Assigned: Vegetation Dynamics and Distribution

 


Close Window