Vegetation Classification and Mapping Project Report - USGS
Vegetation Classification and Mapping Project Report - USGS
Vegetation Classification and Mapping Project Report - USGS
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
<strong>USGS</strong>-NPS <strong>Vegetation</strong> <strong>Mapping</strong> Program<br />
Colonial National Historical Park<br />
Urban or Built-up L<strong>and</strong>, Other Urban or Built-up L<strong>and</strong>, Residential, <strong>and</strong> Transportation,<br />
Communications, <strong>and</strong> Utilities. These map classes are described in Appendix I.<br />
Wetl<strong>and</strong> map classes account for 23.8% of the park area or about 835.9 ha (2065.4 ac). These<br />
map classes include areas of open water on the coastline where the park boundary falls within<br />
large water bodies. Open water is also found on larger tidal creeks in <strong>and</strong> around Jamestown<br />
Isl<strong>and</strong>, <strong>and</strong> in ponds, <strong>and</strong> is mapped as a total of 70.6 ha (174.3 ac). Wetl<strong>and</strong> map classes also<br />
include tidal wetl<strong>and</strong>s (568.5 ha [1404.7 ac]), nontidal wetl<strong>and</strong>s (171.9 ha [424.7 ac]), <strong>and</strong> other<br />
transitional or disturbed wetl<strong>and</strong> vegetation as described above (25.0 ha [61.7 ac]). Tidal<br />
wetl<strong>and</strong>s (including intertidal beaches) cover 16.3% of the park area. Tidal vegetation is<br />
represented by the map classes Salt Scrub, Tidal Bald Cypress Forest / Woodl<strong>and</strong>, Tidal<br />
Freshwater Marsh, Tidal Mesohaline <strong>and</strong> Polyhaline Marsh, Tidal Oligohaline Marsh, <strong>and</strong> Tidal<br />
Shrub Swamp (Wax Myrtle Type).<br />
Tidal Oligohaline Marsh is the most common tidal vegetation in the park (367.8 ha [908.9 ac])<br />
<strong>and</strong> occurs at Swanns Point, Jamestown Isl<strong>and</strong>, Kingsmill / College Creek, <strong>and</strong> as small patches<br />
along King Creek. It is dominated by species indicative of oligohaline conditions, where salt<br />
concentrations are between 0.5 <strong>and</strong> 5 ppt. This map class includes five associations which can<br />
occur singly or in a complex. Much of the vegetation mapped as Tidal Oligohaline Marsh is<br />
either the association Tidal Oligohaline Marsh (Mixed Forbs Type) or Tidal Oligohaline Marsh<br />
(Big Cordgrass Type). Tidal Oligohaline Marsh (Mixed Forbs Type) is dominated by variable<br />
mixtures of tidal forbs such as dotted smartweed (Polygonum punctatum), green arrow arum<br />
(Pelt<strong>and</strong>ra virginica), crimsoneyed rosemallow (Hibiscus moscheutos ssp. moscheutos), <strong>and</strong><br />
narrowleaf cattail (Typha angustifolia). It is currently documented from Virginia, Maryl<strong>and</strong>, <strong>and</strong><br />
New Jersey. Tidal Oligohaline Marsh (Big Cordgrass Type) is dominated by big cordgrass<br />
(Spartina cynosuroides), <strong>and</strong> often forms tall, extensive, nearly monospecific st<strong>and</strong>s, particularly<br />
along edges of the main tidal channels. It is a common marsh association, ranging from Georgia<br />
north to New Jersey. Other associations included in areas mapped as Tidal Oligohaline Marsh<br />
include dense st<strong>and</strong>s of the invasive, nonnative grass, common reed (Phragmites australis), <strong>and</strong><br />
less common associations that occur on the interior of larger marshes. Tidal Oligohaline Marsh<br />
(Common Reed Tidal Marsh) ranges from Texas to Florida <strong>and</strong> north to Canada. Tidal<br />
Oligohaline Marsh (Interior Depression Marsh) is currently only documented from Virginia.<br />
Tidal Oligohaline Marsh (Saltmeadow Cordgrass - Olney Three-Square Low Interior Marsh<br />
Type) has been documented from Virginia to New Jersey, but may extend south to Georgia. Due<br />
to the difficulty of delineating the five associations separately over large areas, these associations<br />
were combined into a single map class that was used in all parks in this study.<br />
Tidal Freshwater Marsh is mapped as 124.8 ha (308.4 ac) <strong>and</strong> is found at Jamestown Isl<strong>and</strong> in<br />
the vicinity of S<strong>and</strong>y Bay <strong>and</strong> the upper portions of the Back River, at Papermill Creek, <strong>and</strong> at<br />
College Creek / Kingsmill along Halfway Creek. Tidal Freshwater Marsh is distinguished from<br />
other tidal marsh vegetation in Colonial National Historical Park by occurring in areas where<br />
there is enough freshwater input to influence the vegetation composition so that the dominant<br />
species include green arrow arum (Pelt<strong>and</strong>ra virginica) <strong>and</strong> annual wildrice (Zizania aquatica<br />
var. aquatica). This association is found on the Atlantic Coast from Maine to Virginia,<br />
excluding New Hampshire <strong>and</strong> Rhode Isl<strong>and</strong>, <strong>and</strong> occupies a relatively uncommon, specialized<br />
habitat. Many examples have been impacted by the damming of tidal rivers <strong>and</strong> by pollution in<br />
urban areas. It is estimated that less than 200 high quality examples remain throughout its range.<br />
76
Change language