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Stocking conditions influence strength of small diameter ponderosa pine wood harvested in forest restoration treatments.
Battaglia, Michael*,1, 2, Shepperd, Wayne1, Mackes, Kurt3, Joyce, Linda1, 1 USDA Forest Service, Rocky Mountain Research Station, Fort Collins, CO2 Management and Engineering Technologies International, El Paso, TX3 Colorado State University, Fort Collins, CO
ABSTRACT- Treatment to reduce risk of catastrophic fire in ponderosa pine forests of the Colorado Front Range requires removal of large numbers of small diameter trees. Many of these trees have grown in highly competitive environments and it is unknown what effect these conditions have on strength properties of these trees. We measured strength properties of 9 to 11 inch diameter open grown (n=15), suppressed (n=20), and mistletoe infected (n=21) ponderosa pine trees. Strength properties were compared to the basal area increment (BAI), heartwood-sapwood ratio and forest density surrounding each tree. Growth rates of open grown trees were 50% higher than suppressed and mistletoe trees, while age and heartwood-sapwood ratio were lower in open grown trees. Modulus of rupture (MOR) was similar for suppressed and mistletoe trees, but lower for open grown trees. Modulus of elasticity (MOE) was highest in the suppressed trees and lowest in open grown trees. MOR and MOE increased with increasing stand basal area and tree ring density, but decreased with increasing individual stem BAI. Different competitive environments impact growth rates, which influence the strength of small diameter wood. Small diameter trees removed from dense Front Range forests appear to be superior in strength than rapidly growing young trees of the same size.
Key words: ponderosa, growth, restoration, strength