Initial tree census for the Paint Rock Forest Dynamics Plot, Alabama, USA

We present the initial woody stem census for the 20-ha Paint Rock Forest Dynamics Plot in 2019-2021 in north Alabama, USA. Our objectives were to improve our understanding of the ecology of the forest ecosystem, provide hands-on research experience to undergraduate students, create opportunities for collaboration with other disciplines, and monitor the dynamics of the forest. From its origin at the south corner (latitude: 34.769521°, longitude: -86.306079°), our plot is a rectangle of 400 m × 500 m, having its long side at 313° azimuth. The plot is in a mature mixed deciduous forest within the mountain district of the Cumberland Plateau physiographic region. It is within the Nature Conservancy Sharp Bingham Mountain Preserve (1600 ha). The Preserve is protected from broad anthropogenic disturbance, but allows limited hunting outside of the plot. The plot's climate is humid subtropical, with hot, humid summers and cool, wet winters. The plot is on a deeply dissected karst landscape with a sandstone cap overlaying several layers of limestone. The majority of the plot (95%) is limestone rockland rough soils that are well-drained with a parent material of residuum weathered from limestone. The remainder of the plot (5%) is Huntington silt loam, which occurs in the floodplains and toe slopes. The variable geology and topography offer a broad range of water availability, from dry benches to moist bottomland sinks, with steep to moderate slopes in between. Elevation ranges from 226 to 323 m above sea level. A 20 m × 20 m grid was professionally surveyed and installed across the 20 ha. Using this grid, we mapped and inventoried all living stems of woody plants (excluding vines) with a diameter of at least 1 cm at breast height. Trees with multiple stems were defined as those with aboveground forks off the main trunk, below breast height, at an angle <45° from the main stem, and having a diameter at least one-third of the main stem. Clonal trunks that were clearly connected below ground were also recorded as multiple-stemmed. Trees were mapped using a laser rangefinder with an internal digital compass, which measured the distance and azimuth from true north to the base of each tree from one corner of the 20 m × 20 m survey grid. These were converted to x-y coordinates. Our taxonomic nomenclature follows that of the PLANTS database online, the Flora of the Southeastern United States, and the Alabama Plant Atlas. The initial census enumerated 29,280 free-standing living stems from 27,418 woody individuals, including 79 species from 35 families. Among those were three gymnosperm and 46 angiosperm canopy stature trees (species that could potentially reach the canopy as free-standing trees), and 30 species of mid- or understory tree species and shrubs. Canopy stature tree species made up 74.5% of the stems. Dominant canopy trees include white oak (Quercus alba), yellow-poplar (Liriodendron tulipifera), sugar maple (Acer saccharum), white ash (Fraxinus americana), southern shagbark hickory (Carya carolinae-septentrionalis), and American beech (Fagus grandifolia). This data set can be freely used for non-commercial purposes. We request that users of these data cite this data paper in all publications resulting from the use of this data set.