Tree measurements from old-growth and second-growth forest stands in southeast Alaska

This data publication includes three different datasets containing tree measurements from old-growth and second-growth forest stands in southeast Alaska. The measurements are compilations from four past research projects conducted by the USDA Forest Service, Pacific Northwest Research Station in Juneau, Alaska. The Cooperative Stand Density Study (CSDS) (1974-2003) and the Taylor Growth and Yield Study (Taylor plots) (1926-2003) were conducted in second-growth stands and measurements are combined into a single dataset. The Alternatives to Clearcutting study (ATC) (1995-2005) and the Juneau Hydrologic Observatory project (Juneau carbon) (2008) occurred in old-growth stands and measurements are provided as two separate datasets. Each dataset contains sample plot measurements of tree diameters and heights. In addition, the second-growth dataset includes ingrowth tree measurements, tracks tree death, tallies cut trees, and includes plot site index, stand age, and stand treatment information. Site locations are provided for all four studies as well as detailed information and graphics related to the study design and treatments.
The objectives of the Taylor Plot and CSDS studies were to obtain accurate data on growth and yield in unthinned and thinned even-aged second-growth western hemlock and Sitka spruce stands in southeast Alaska. Taylor plots (established 1926-1931 and 1963) are unthinned whereas the CSDS sites (established 1974-1987) contain a range of thinning treatments plus unthinned control plots. Stands originated from logging (primarily), fire, or blowdown.

The ATC study (1995-2005) was designed to assess the ecosystem, societal, and economic impacts of various partial harvest logging treatments in old-growth stands in southeast Alaska. Stands are a mix of hemlock, spruce, and cedar.

The Juneau Carbon overstory plots are part of the Juneau Hydrologic Observatory, which was established to collect hydrologic and carbon measurements from three representative landscape types in southeast Alaska (upland forests, forested wetlands, fens). The Juneau Carbon plots are in old-growth stands and were inventoried in 2008.
The measurements contained in this data package are only a subset of the full suite of variables that were originally collected for the four studies. This publication provides the data that were used by Jones et al. (2026) to develop forest carbon accumulation models for the Tongass National Forest. While other forest measurement datasets for Tongass National Forest may exist, the four datasets published here were the ones available and suitable for use in the Jones et al. (2026) model development at the time.