Soil profile morphology and chemistry, Allegheny National Forest, PA, 1997-2017

These data are associated with a 50-year study of soil change on the Allegheny National Forest in northwestern Pennsylvania that began in 1967. In 1997 and 2017, we relocated and sampled 4 of the sites originally sampled in 1967. At each site and each year, four test pits were dug by backhoe. Soil profiles were described and sampled by genetic horizon. In addition, 10 forest floor pin blocks were sampled at each site in 1997, 1998, 1999, and 16 at each site in 2017. Samples were subject to a number of chemical analyses. This data publication consists of three files that include (1) soil horizon samples from 32 backhoe-dug pits, 16 sampled in 1997 and 16 sampled in 2017 where each genetic soil horizon is described using standard soil morphology procedures and analyzed with typical soil analytical methods for pH, extractable cations, and total carbon and nitrogen; (2) quantitative pinblock samples for thickness of forest floor (Oi, Oe, Oa, and A) horizons; and (3) quantitative pinblock samples for mass of forest floor (Oi, Oe, Oa and A) horizons and chemistry (same parameters as the pit samples) for Oa and A horizons only.
These four sites relocated exactly in 1997 were undisturbed since their original sampling in 1967, affording a unique opportunity to assess soil change during a period of high atmospheric acid deposition. The Allegheny Plateau received some of the highest acid deposition levels in the USA and forest impacts in this region included an expansion of sugar maple decline disease and acidification of streams, with impacts to native brook trout populations. These data documented soil acidification changes that were drivers behind these environmental impacts. This is one of the only direct measurements of long-term response to acid deposition in forest soils in the USA. In 2017, the sampling was repeated to evaluate recovery from acidification after a period of strongly declining acid deposition. In sum, our sampling in the late 1990s and 2017, coupled with previously published work on samples collected in 1967 by Penn State scientists, creates a fifty-year record of soil dynamics, perhaps the longest such record for forest soils in the USA.
For more information about this study and these data see Bailey et al. (2021).