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
Plot Quality Fields:
Plot Validation Level
(2) classification plot: sufficient for inclusion in a classification revision
Overall Plot Vegetation Fields:
Field Height
5
m
Field Cover
90
%
Misc Fields:
Observation Narrative
This stand of low marsh strongly dominated by Zizania aquatica is located ca. 50 m from unnamed "thoroughfare" through Sweet Hall Marsh. Although cover is high throughout the northern reaches of Sweet Hall Marsh, the stature of Zizania culms is noticeably shorter (1.5 m vs. 2 - 2.5 m) than in similar stands at Cumberland Marsh. Density also appears to decrease the interior the marsh, and species richness is exceptionally low. All of these phenomena likely reflect the higher halinity at Sweet Hall and the upstream migration of the halinity gradient and the freshwater-oligohaline interface in recent decades. Fine-scale richness may frequently be low in marsh habitats such as this, in which one species preempts much of the light resource, but vegetation patchiness over a large extent may contribute to high gamma diversity over the entire marsh. Phragmites australis occurs in several patches at Sweet Hall, but none is located near plot. Water depth ca. 43 cm at time of sampling (1.5 - 2 hr before high tide), so it is unclear whether this marsh drains completely with every tidal cycle. High water makes a complete species list an uncertain endeavor.
