Plants of Cascadilla Gorge
The sunny south-facing slopes host vegetation adapted to dry conditions, with species such as chestnut oak, scarlet oak (Quercus coccinea), hickories (Carya), and shadbush (Amelanchier). Here also are some locally scarce species; this is one of the few sites in the region were pitch pine (Pinus rigida) is found. The shady, damp, cool gorge bottom and north-facing slopes host hemlock (Tsuga canadensis), beech (Fagus grandifolia), sugar maple (Acer saccharum), and mountain maple (Acer spicatum). There are ferns, mosses, lichens, and liverworts on the rock faces.
The creek bed is constantly changing. Where rocks and gravel have temporarily stabilized, tree species typical of floodplains – sycamore (Platanus occidentalis), cottonwood (Populus deltoides), and box elder (Acer negundo) – have taken hold. Impacts of human activities on this narrow greenway are extreme. Invasive exotic species proliferate in the naturally disturbed conditions of the gorge. Many are ornamental plants that must have dropped from gardens above.
Cascadilla Gorge is constantly eroding, and rocks continue to fall from the cliff sides, especially when the water flow is high and during freeze-thaw cycles in early spring. Both small and very large rocks, and trees as well, may tumble into the gorge. Many of the trees have a bend at the base. When soil on these steep slopes slides downhill, the trees may become tilted. Later they bend to become vertical again. Erosion and landslides are exacerbated by human activities such as construction and changes in drainage near the gorge edge.
Hemlock-northern hardwood forest
A forest that typically occurs on lower slopes of ravines, on cool, mid-elevation slopes, and at the edges of drainage divide swamps. Hemlock is a co-dominant species with one to three others: beech, sugar maple, red maple, black cherry, white pine, yellow birch, black birch, red oak, and basswood. Shrubs have low abundance, but striped maple may be present. Herbs characteristic of northern and montane areas are common.
A forest usually found on hilltops and south to west facing slopes. Soils are acidic and well to moderately well drained, but usually have restricted rooting depth due to fragipan or bedrock. Beech, pine, or aspen may be among the dominant trees and trees of cool microclimates such as birch, hemlock, and striped and mountain maples are abundant in this ecological community type. Shrubs and herbs are abundant and moderately diverse.
The aquatic community of a stream that has a well-defined pattern of alternating pool, riffle, and run sections. Waterfalls and springs may be present. Typical aquatic macrophytes include waterweed and pondweeds. Persistent emergent vegetation is lacking.
Shale cliff and talus community
A community with sparse vegetation that occurs on nearly vertical exposures of shale bedrock, ledges, and talus. The talus is unstable, there is little soil. Characteristic species include blunt-lobed woodsia, rusty woodsia, hairy penstemon, herb-Robert, panic grass, Carex pensylvanica, and eastern red cedar.
Shale talus slope woodland
An open to closed canopy woodland that occurs on talus slopes composed of shale. Slopes are unstable and very well drained. Soils are shallow and dry. Canopy cover is less than 50%. Characteristics trees include chestnut oak, pignut hickory, red oak, white oak, white pine, white ash, and eastern white cedar. Characteristic shrubs include smooth sumac, poison ivy, hairy penstemon, everlasting, and Pennsylvania sedge.
Cliff and talus communities on shale
Open communities with less than 25% trees on a shale substrate. The Shale cliff and talus community and Shale talus slope woodland communities are often found together. The woodland community is structurally intermediate between forests and open canopy upland of the cliff and talus community.
Rocky headwater stream
The aquatic community of a small to moderate sized rocky stream with a moderate to steep gradient that lacks persistent emergent vegetation. The cold water stream flows over eroded bedrock near the stream origin and contains alternating riffle and pool sections. These streams typically have mosses and algae present, but few larger rooted plants.