Given particular site conditions, then characteristics of trees in the stand also have important effects on the risk of insect attack.

EXAMPLES

Mountain pine beetle. Dense, overstocked stands with small crown-to-bole ratios (slide) have lower resistance to bark beetle attack, but also tend to have a thinner and less nutritious phloem tissue. Open-grown stands with large crown-to-bole ratios (slide) are usually resistant to attack but may have thick, nutritious phloem. Risk rating systems for the mountain pine beetle are often based on phloem thickness and stand resistance, with highly susceptible stands having thick phloem and low resistance to attack.

Southern pine beetle. Hazard rating systems have been developed based on site and stand conditions (slide).

<Use BACK key to return to Sessions>