• Document relationships among soil chemical, biological, and physical characteristics and site series/tree productivity.
• Examine selected biological processes such as soil respiration, litter decomposition, and organic matter dynamics (rates of forest floor and peat accumulation; soil faunal and microbial activity) in relation to forest productivity and bedrock type.
• Examine the potential for manipulating soil characteristics, through logging and site treatments, and improving second growth tree productivity.

Our ecological plots and field observations suggest forest productivity on the outer coast reflects the interactions of many soil variables: depth and nature of the forest floor, depth and nature of underlying mineral soil, bedrock geology, soil hydrology, slope, and disturbance history.  Understanding how and why each of these influences impacts on site productivity and how they all interact to yield a specific forest ecosystem is the challenge of the soil ecology component.  This information is essential for identifying sites having potential for timber management, and for developing  treatments that will maintain or improve site productivity.

Typical cedar-hemlock low-site soil profile - deep organic layer over thin mineral soil over bedrock.

We are focussing the soil ecology research on forest floors, examining how they differ across forest productivity gradients.  Organic matter dynamics are closely tied to vegetation composition and productivity.  On the north coast, forest floors are relatively thick (commonly >30cm) and comprise much of the rooting zone.  From previous sampling, we know that contrasting bedrock types, (from the harder, massive granites to the softer, cation-rich schists and limestones) affect soil nutrient status and, therefore, ecosystem composition and productivity.  We are unsure how forest floor turnover (respiration) and chemical characteristics would reflect these bedrock types, and whether mechanisms controlling organic matter dynamics could be identified.  In our preliminary work we assessed organic matter dynamics on freely drained sites (site series 04, 05, 06; Banner et al. 1993) occurring on four contrasting bedrock types.  We plan to extend these results to studies on the lower productivity, wetter sites and assess whether site manipulations to improve productivity are operationally feasible.  This information, combined with the results of the soil hydrology and regeneration/ productivity studies, will feed directly into the operational research trial component.

References:

Banner, A., W. MacKenzie, S. Haeussler, S. Thomson, J. Pojar and R. Trowbridge. 1993. A field guide to site identification and interpretation for the Prince Rupert Forest Region; Parts 1 and 2. Res. Br., B.C. Min. For., Victoria, B.C. Land Mgmt. Hand. No. 26.