PITS AS NATURAL IRREGULARITIES IN SOFTWOOD FIBERS

Parameters for pit size, shape, orientation, and density, and their co rrelations with fiber dimensions in Scots pine and Norway spruce fiber s were determined. Bordered pits were smaller with greater cross-secti onal fiber area, and more circular the wider the fibers. Angular pit o rientation became more transverse in pine fibers, and pit density incr eased in both species with fiber width. Normalized pit size and pit de nsity increased towards fiber tips, especially in thin-walled pine fib ers. These observations can be explained by the developing process and the functional role of tracheids in wood. The appearance of pits as s tress-enhancing irregularities in fiber structure should be considered in fiber-network theories predicting paper properties, as well as in the measurement of the mechanical properties of fibers.