Initial spacing influences 20-year growth and development of red alder

Red alder (Alnus rubra)(Bong.) seedlings were planted in northwestern Oregon in the winter of 1974-1975 at five spacings ranging from 0.6 × 1.2 meters (m) to 2.5 × 2.5 m. The four narrower spacing treatments were planted in a completely random design on 0.04-hectare (ha) plots at exact spacings. Two other plots came from an adjacent area that was used for a test of red alder as a biological control for laminated root rot and planted at an approximate spacing of 2.5 × 2.5 m. There were originally 7 plots in this study, and 2 additional plots from an adjacent area were also included because they were planted at the same time with the same stock. This data publication contains data such as tree diameter, height, base to live crown, and tree condition which were measured multiple times between 1981 and 1994. In 1990 live and dead branches were counted as well as the count of live epicormic branches and presents of dead epicormic branches. Also included is monthly precipitation data for a nearby NOAA weather station.
The trial was initially established adjacent to another trial to determine if a short rotation of red alder or black cottonwood could reduce infection by Phellinus wierii on Douglas-fir. However, these plots were established to study the effects of spacing and rectangularity on growth and stand development of red alder as very little information was available from planted stands.
For more information about these data see DeBell and Harrington (2002).