自然保护与休闲部保护·守护·共享
自然保护与休闲部
目录沙丘间洼地和池塘
洼地、洼地和海上沙丘中的低洼平地养育了各种饱和的和季节性淹没的草本植物和灌木为主的湿地。由于植物群落的季节性变化、林分随时间的演替、时间水文变化以及动态沙丘系统的快速地貌变化，该组中的群落的组成变化很大，难以分类。据了解，它们的分布范围从新泽西州到北卡罗来纳州，有些甚至延伸到更南的地方。在弗吉尼亚州，这些湿地仅限于从东岸（阿可麦克县和北安普敦县）到亨利角和福尔斯角（弗吉尼亚海滩市）的屏障海滩后面的区域。沙丘间洼地和池塘的植被往往沿着地理、地形和水文梯度排列。
Swales and low dune hollows that have perched water tables and shallow, seasonal or temporary flooding support maritime wet grasslands or shrublands. The swales are predominantly influenced by fresh water from rainstorms, but some may be periodically flooded by salt water from ocean storm surges. A thin, organically enriched, surficial soil layer often contributes to moisture retention. Hydrologic regime and distance from salt spray appear to exert considerable influence on floristic composition. Typically, occurrences are densely vegetated by one or more species of grasses (e.g., saltmeadow cordgrass [Spartina patens]); rushes (e.g., Juncus scirpoides, Juncus dichotomus, Juncus acuminatus, Juncus megacephalus, or Juncus canadensis); or sedges (e.g., Cyperus odoratus var. odoratus, Fimbristylis caroliniana, or Schoenoplectus pungens var. pungens). In smaller, temporarily flooded swales where rushes are dominant, slender flat-top goldenrod (Euthamia caroliniana), long-leaved aster (Symphyotrichum novi-belgii var. elodes), Richard's yellow-eyed grass (Xyris jupicai) and slender bladderwort (Utricularia subulata) may also be characteristic. Swales further inland contain additional assemblages of species, including dwarf umbrella-sedge (Fuirena pumila), ladies'-tresses (Spiranthes spp.), water sundew (Drosera intermedia), southern bog clubmoss (Lycopodiella appressa), white-top fleabane (Erigeron vernus), whorled nutrush (Scleria verticillata), and narrow-leaf whitetop sedge (Rhynchospora colorata). Successional invasion of these herbaceous assemblages by shrubs increases with distance from salt spray and stability of the habitat. Wax myrtle (Morella cerifera) is the most characteristic interdune shrubland species, with high-tide bush (Baccharis halimifolia) frequently associated and northern bayberry (Morella pensylvanica), red bay (Persea palustris), and yaupon (Ilex vomitoria) present at some sites.
沙丘间池塘是被洪水淹没最持久、最深的沙丘间湿地，包括淡水池塘和微咸水池塘，淡水池塘中的雨水和地下水会迅速稀释不频繁的咸水输入，而微咸水池塘则会更频繁地受到咸水输入。后者的盐度似乎会随着时间推移而变化，从完全淡水到略微中盐，可能最适合被描述为少盐池塘。群落组成随地理位置、地形位置、风暴潮和盐雾暴露、水文周期和土壤特性而变化。季节性淹没的淡水池塘通常含有大量芦苇（例如， Scirpus cyperinus 、 Schoenoplectus pungens var. pungens 、 Schoenoplectus tabernaemontani ）、草类（例如， Panicum virgatum var. virgatum 、 Coleataeniarigidula ssp.condensa 、 Spartina patens ），或方茎穗草 ( Eleocharisquadrangulata )。一些淡水池塘的边缘地带可能主要以近乎纯粹的草本植物（ Cladium mariscoides ）为主。季节性淹没的寡盐池塘可能以窄叶香蒲 ( Typha angustifolia )、沼泽玫瑰锦葵 ( Hibiscus moscheutos ) 或盐沼灯芯草 ( Bolboschoenus robustus ) 为主，其成分类似于潮汐寡盐沼泽。半永久性淹没的低盐池塘主要生长着滨海水生植物（ Bacopa monnieri ）、白荸荠（ Eleocharis albida ）和西米草（ Stuckenia pectinata ）。
该群体内的所有类型对于脆弱环境中存在的稀有小块群落来说都是不常见的。它们还为几种州珍稀昆虫提供栖息地，包括虎甲虫（ Cicindella trifasciata ascendens ）和蜻蜓（ Anax longipes ）。与大多数海洋社区一样，这一群体面临的威胁包括发展和海平面上升。
参考：大自然保护协会 ( 1997 )。
© DCR-DNH，加里·P·弗莱明。
下载下面列出的每个社区类型的组成汇总统计电子表格。
