PARENT SESSION
Contributed Oral Session 19: Modeling: Movement and Population Dynamics
Monday, August 8, 1:30 PM - 5:00 PM, Meeting Room 513 A, Level 5, Palais des congrès de Montréal
Moisture content characteristics of the forest floor organic layer for the purposes of large scale distributed modelling.
Raaflaub, Lynn*,1, Valeo, Caterina1, 1 University of Calgary, Calgary, Alberta, Canada
ABSTRACT- The floor of the boreal forest is covered by a layer of decomposing organic matter known as duff. Duff consumed during forest fires exposes the mineral soil which is a seedbed more conducive to seedling recruitment than the duff layer. The location and amount of duff consumed is a function of characteristics that include its density, depth and, in particular, moisture content. Distributed modelling of duff moisture content over large scales is an important tool in managing forest resources, yet knowledge of duff characteristics essential to distributed modelling is still lacking. In an attempt to quantify some of the characteristics of duff that spatially determine moisture content, a number of laboratory experiments were carried out in a controlled environment on duff from six different forest stands (Popolus tremuloides, Picea glauca, P. mariana, Pinus banksiana, P. contorta and mixed) over two extremes in duff thickness: between trees, where the duff tends to be at its thinnest, and beside trees, where the duff tends to be at its thickest. These experiments were designed to establish drying curves, water absorption and retention relationships for different rainfall intensity events, the moisture exchange between the duff layer and the mineral soil, moisture characteristic curves and density variations. Density and moisture characteristic curves were found to exhibit greater variation vertically within the duff layer then between tree type and location. Results also indicate that duff moisture is not influenced by soil moisture, thus negating previous hypotheses that duff moisture may be a function of hillslope position. From these results it was concluded that spatial models of duff moisture can be based solely on meteorological conditions, canopy composition, stem density and the hydrological characteristics of duff.
Key words: forest floor, soil moisture, large scale modelling