Our long-term data sets have allowed us to study population changes resulting from spatial changes (a timber harvest) against a backdrop of changes over time. Starting in 1983, we collected five years of baseline data on the 40-ha study area. In the winter of 1987-88, we performed a selective harvest on ten randomly selected, 1-ha blocks on the 20-ha "managed" side. From 1988 to present we have collected post-harvest data from both the "managed" and unharvested, "control" sides.
We have prepared a detailed techniques manual for conducting research at the Holt Research Forest (Witham et al. 1993) to assure that our data are collected consistently over long periods. The manual also facilitates the comparison and sharing of data with other research projects, and has been used as a model by other forest ecosystem researchers.