Releve Virginia Division of Natural Heritage, see http://www.dcr.virginia.gov/natural_heritage/documents/nh_plotform_instructions.pdf
Overall Taxon Cover Values are Automatically Calculated?
no
Stem Observation Area
400
m²
Plot Quality Fields:
Plot Validation Level
(2) classification plot: sufficient for inclusion in a classification revision
Overall Plot Vegetation Fields:
Tree Height
38
m
Shrub Height
6
m
Field Height
8
m
Tree Cover
90
%
Shrub Cover
75
%
Field Cover
40
%
Misc Fields:
Observation Narrative
Plot location: bluff along Broad Run, 1.13 km SSE of Jct. Rts. 55 and 600 in Thoroughfare Gap. Not permanently marked. Rock types present: Small muscovite schist and quartz fragments (conglomerate outcrops just downstream).
This plot is located near the top of a steep slope along Broad Run at the east foot of Pond Mountain. Fertile loamy soil is apparently weathered, at least in part, from underlying Triassic border conglomerates that appear to contain some carbonate (marble?) clasts, accounting for the relatively high (for the Bull Run Mountain area) pH and Ca values. The stature of many overstory trees on this site is impressive (up to 38 m tall, 94 cm DBH), although some very selective cutting apparently took place here within the past few decades. Vegetation is a rich mixed hardwood forest with dense Asimina triloba and Lindera benzoin understory. Several locally uncommon herbaceous species were recorded here (e.g., Cystopteris protrusa, Hydrophyllum virginianum, and Asarum canadense). A return visit in the spring would be desirable since some ephemeral herbs were undoubtedly missed on this late spring sampling date. Shade-tolerant exotic weeds such as Alliaria petiolata are problematic on this fertile site.