自然保护与休闲部保护·守护·共享
自然保护与休闲部
目录山麓硬盘森林
This ecological group contains a group of oak-hickory forests that occupy gentle to flat Piedmont uplands with impermeable clay subsoils. On high bedrock terraces of the Potomac Gorge in northern Virginia and occasionally elsewhere, flat-lying bedrock underlying shallow soil acts as a surrogate "hardpan" and supports similar vegetation. Piedmont Hardpan Forests occur from Virginia south to Georgia. Sites are usually underlain either by mafic rocks such as diabase or by acidic slates. Surficial soils are silt or clay loams, with an abrupt transition to heavy, plastic clay hardpans at depths of 23 to 38 cm (9 to 15 in). These shrink-swell clay soils pond water for brief or, at a few sites, prolonged periods during rainy weather, but tend to be very hard and dry during significant portions of the growing season. Post oak (Quercus stellata) is the most typical overstory tree, growing in nearly pure stands or in variable mixtures with pignut hickory (Carya glabra), Carolina shagbark hickory (Carya carolinae-septentrionalis, only in Charlotte, Halifax, and Pittsylvania counties), white oak (Quercus alba), blackjack oak (Quercus marilandica var. marilandica), Virginia pine (Pinus virginiana), and white ash (Fraxinus americana). Virginia pine increases following cutting and may dominate on heavily disturbed, clear-cut sites. Winged elm (Ulmus alata), sweetgum (Liquidambar styraciflua), and eastern red cedar (Juniperus virginiana) are characteristic understory trees. Shrubs include eastern redbud (Cercis canadensis var. canadensis), black haw (Viburnum prunifolium), fringetree (Chionanthus virginicus), and blueberries (Vaccinium spp.). In closed stands, there is often little herbaceous growth, while more open stands support large patches of xerophytic graminoids such as poverty oatgrass (Danthonia spicata), eastern needlegrass (Piptochaetium avenaceum), and little-headed nutrush (Scleria oligantha).
林分位于古老的、从未被洪水淹没的河道阶地上，阶地上的水塘长期生长着高地和湿地物种的特殊混合物，但它们的水文状况存在问题，因此在这里它们被视为陆地系统的群落。在这些周期性潮湿的变种中，柳橡树 ( Quercus phellos )、枫香树 ( Liquidambar styraciflua )、落叶冬青树 ( Ilex decidua) )、多毛高丛蓝莓 ( Vaccinium fuscatum )、圣彼得草 ( Hypericum crux-andriae ) 和喙莎草 ( Rhynchospora spp.) 与上面列出的旱生物种混合在一起。
山麓硬盘森林散布在整个山麓地区的特殊土壤环境中，在弗吉尼亚州被认为是罕见的。北部硬盘区基本橡树 - 山核桃林 (CEGL 006216 ) 目前属于基本橡树 - 山核桃林 ECG 范畴，也可归入此组，但其生长的基质具有略微不同的底土特性。
参考文献：Fleming ( 2002 a)、Fleming ( 2007 )。
© 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。
