Cover PhotoMontane ecosystems, as seen from Mount Jefferson on the White Mountain National Forest. These ecosystems are particularly vulnerable to climate change. Photo by Toni Lyn Morelli, U.S. Geological Survey.

Forest growth models attempt to quantify the growth of a forest, and are commonly used for two principal purposes: to predict the future status of a forest and the nature of any harvests from that forest; and to help consider alternative cultivation practices. Models may also find other uses, such as in education, communicating information, etc. Depending on the purpose of the model, modelers may choose to emphasize physiological detail or statistical efficiency, but generally seek both biological and statistical accuracy.

Northern white-cedar (eastern white cedar; Thuja occidentalis L.) is an important tree species in the northeastern United States and adjacent Canada, occurring both in pure stands and as a minor species in mixed stands of hardwoods or other softwoods. Yet practitioners have little and often contradictory information about cedar ecology and silviculture. In response to this information need, a group of university and government researchers in the United States and Canada embarked on more than a decade of collaborative research; this guide is a compilation of the knowledge generated by that effort. It includes an overview of the commodity and non-commodity values of cedar, silvics of cedar and companion species, descriptions of the cedar resource in the northeastern United States, Quebec, and Ontario, and silvicultural guidelines based on previously published literature and new studies of cedar regeneration, growth, mortality, site relationships, and responses to treatment. With generally slow growth and little to no ingrowth on most inventory plots in the region, silvicultural prescriptions that explicitly address cedar are warranted. Recommendations include retaining and releasing cedar in managed stands, as well as establishing and protecting advance cedar regeneration and residual trees during harvesting. Partial cutting (e.g., the selection or irregular shelterwood method) is suggested for regenerating stands with a component of cedar, though browsing by white-tailed deer (Odocoileus virginianus Zimmermann) may infl uence treatment outcomes and must be considered. Once established, cedar responds well to release and will benefi t from competition control and thinning. In mixedspecies stands, within-stand fl exibility of treatment is critical for maintaining cedar when other, more dominant species are driving silvicultural prescriptions at the stand level; a "micro-stand" approach in which pockets of cedar are identifi ed and managed is suggested.

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Forest growth models attempt to quantify the growth of a forest, and are commonly used for two principal purposes: to predict the future status of a forest and the nature of any harvests from that forest; and to help consider alternative cultivation practices. Models may also find other uses, such as in education, communicating information, etc. Depending on the purpose of the model, modelers may choose to emphasize physiological detail or statistical efficiency, but generally seek both biological and statistical accuracy.