Monitoring stand structure and dynamics

The feasibility and results of the small-scaled management regimes as well as the gradual change in the forest structure and dynamics in the study areas are among the basic research themes in the project. Key questions include:

• What kind of forest structures and associated dynamic patterns do evolve through the application of natural disturbance-based management, and how do the forests differ from contemporaneous managed and natural forests?
• How well does disturbance-based management maintain the sustainability of timber production and economic viability of forestry?
• How does disturbance-based management maintain non-wood products and other services and values in the forests?

A permanent network of monitoring plots will be established in experimental stands subject to variable treatments. Tree and stand development, including regeneration, will be intensively monitored. The plot network will also constitute a framework for other studies that utilize precise long-term tree and stand data.

Prior experience has shown that intensive, spatially explicit observation is required to monitor and analyze the effects of small-scaled silvicultural treatments. For example, trees on the edge of a clear-cut patch affect seedling survival and growth up to at least 20 m away. Regeneration and juvenile development of the stand are substantially different at different parts of gaps and small clearcuts. The main crop trees also influence each other through light and root competition, which are important factors to be controlled when studying selection cuttings and thinnings. Regeneration plots must be monitored for a long time before any pertinent conclusions can be drawn in selection and gap felling, for instance.

The following example (plot design in gap cutting) sheds some light into what kind of monitoring plots are envisaged in the project:

Two perpendicular 2 m-wide sampling strips are placed across a harvested gap, extending up to 10 m outside the plot into the remaining stand matrix. All saplings of 0.1-5.0 m in height will be mapped and measured on the strips. Trees
(>5 m in height) up to 10 m distance from the central line of each strip will be measured and mapped. Initial measurements will be carried out after cutting (and site preparation, if applied). Follow-up inventories are made every 3-5 years. This type of intensive monitoring regime with spatially explicit repeated measurements will produce detailed data on the condition, survival, and development of each individual seedling, sapling and tree on the plot.