Woodland Health: A column focusing on topics that might limit the health, vigor and productivity of our private or public woodlands

摘要

The Pine-leaf Adelgid (Pineus pinifoliae)I think its human nature to notice something, remark on it in our minds, and then let it go because it was not such a big deal. In forest health these little things can be significant. Understanding what is going on with a forest pest when it is not a problem gives us insight into the circumstances that trigger a change either in time or over the landscape that can make the pest a problem. This balance doesn't exist with invasive non-native pests because they have not co-evolved with the host trees likeeastern hemlock and Hemlock Woolly Adelgid or our native ash and the Emerald Ash Borer. However, since native forest pests have co-evolved with their host trees the trees usually have some degree of resistance. In order for these insect populations to go epidemic and cause loss of growth or even death of trees something biotic or abiotic must occur to alter the health of the host tree or alter the impact of natural enemies. Understanding these mechanisms helps us understand the pest and thereby manageits impact in the forest.