Hardwood surfaces erosion

In related work on the relationship of wood density to weathering rate. Sell and Feist (77) investigated the artificial weathering of 12 hardwoods and 6 softwoods. The surface erosion rate was measured with a light microscope at exposure intervals of 600 h. The results showed that the erosion rate per unit time depended predominantly on the wood density and thus on the wood cell wall thickness. The relationship was approximately linear within a wood density range of 0.3-1.0 g/cm. ... 

Erosion of wood cell walls by soft rot fungi is less commonly reported. Hyphae growing in the cell lumen release enzymes that produce erosion patterns on the cell wall surface. These can take several forms including V-shaped nicks or smooth erosion troughs around the hypha, but in general, this type of attack is more prevalent in susceptible hardwoods than softwoods. 

The weathering process is a slow-acting surface phenomenon. Most softwoods erode at an average rate of approximately 1/4 in. per century, whereas dense hardwoods erode at a rate of only 1/8 in. per century. In cold northern climates erosion rates as low as 1/32 in. per century have been reported. Western red cedar, which is a typical very-low-density softwood, may erode at a rate as high as 1/2 in. per century. 

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