Sampling and measurement protocols for long-term silvicultural studies on the Penobscot Experimental Forest

The U.S. Forest Service, Northern Research Station has been conducting research on the silviculture of northern conifers on the Penobscot Experimental Forest (PEF) in Maine since 1950. Formal study plans provide guidance and specifications for the experimental treatments, but documentation is also needed to ensure consistency in data collection and sampling protocols. This guide details current sampling and measurement protocols for three of the longest running Forest Service experiments on the PEF: (1) the management intensity demonstration (1950 to present), (2) the compartment management study (1952 to present), and (3) the auxiliary selection cutting study (1953-present). Each of these long-term stand-scale experiments use plot-based measurements of trees taken at periodic intervals. Additional data collected vary and include regeneration, recruitment, and mortality; amount, size, and decay of dead wood; and stand structural characteristics such as heights, crown dimensions, and spatial locations of trees. Descriptions provided here are the basis for data collection in the relevant studies on the PEF, inform interpretation of the published databases, and serve as a model for silvicultural studies elsewhere.