Research topics

Current research within the old-growth dynamics project focuses on understanding the variability of old-growth forests across the coast, determining the role of disturbances like wind and flood in shaping these forests, and the within-stand variation of these old forests.

On this page:

• Structural and compositional variability of coastal, old-growth forests 
• Influence of disturbance regimes on old forest characteristics  
• Within-stand variation of old forests

Structural and compositional variability of coastal, old-growth forests 

Full title of research area: 

• Structural and compositional variability of old-growth, riparian forests across the coastal temperate rainforest biome

Examining the structural attributes and species composition plant communities in these forested floodplain ecosystems helps us to:

• Refine our classification of coastal forests and, specifically, forested floodplains across climatic units
• Delineate more accurately these floodplain units to support conservation and management
• Understand the relative roles of climate, site, and disturbances on these ecosystems (see below)

Influence of disturbance regimes on old forest characteristics

Full title of research area: 

• The relative roles of disturbance regime, climatic conditions, and site heterogeneity on vegetation structure, composition, and dynamics

Forested floodplains are highly dynamic in space and time across the coastal temperate forest landscape. Variation in site conditions, disturbance regimes, and climate contribute to development of unique vegetation patterns. We expect that characterization of these ecosystems from landscape to stands will contribute to management initiatives such as:

• Policies and guidance for management of riparian plant communities at the interface of land and water
• Ecosystem-based management (EBM) in the Great Bear Rainforest and Haida Gwaii
• Restoration activities, and
• Evaluation of terrestrial carbon budgets

We used data from two of the spruce floodplain stands within the plot network (Carmanah, CAF; Kitlope, KIF) to begin asking:

• What roles do site type, disturbance regime, and latitudinal climatic differences play in driving patterns of:
  • Species composition and structure of the forest canopy
  • Species composition and structure of downed wood
• How and why would differences over time (decades) in structure and composition differ between these locations
• How does understanding of these influences on composition and structure change with measurement scale

These two floodplains were chosen as pilot study units as they represent extremes of latitudinal difference north and south within our current plot network and provide contrasting site types and disturbance conditions.

Within-stand variation of old forests

Full title of research area: 

• Effects of within-stand variation in old growth forest light environment on understory vegetation

Fine scale disturbances (e.g., death of one to a few trees) and development of forest stands create spatial diversity of overstorey structure and light transmission that may influence the structure and composition of understorey plant communities. Halpern and Spies (1995) hypothesized that “a shifting mosaic” of resources may explain why late seral forests have greater plant species diversity, and significantly greater abundance of some (‘late-seral associated’) species, than most younger stages of forest stand development.

When applied to old-growth, this hypothesis predicts that variation of understorey plant communities is organized along environmental gradients within stands. This research, conducted through Simon Fraser University in collaboration with the Province, examined this and related hypotheses by studying variation of understorey vegetation along gradients of light, overstorey structure, and substrate (e.g., soil) characteristics.