Natural Communities of NH -- Photo Guide

Rich red oak rocky woods  (S2S3)

Rich red oak rocky woods
contain a mix of medium-size trees, often growing among the mossy boulders of talus slopes. This woodland natural community occurs on steep, rocky, south-facing slopes below 2,000 ft. in central and southern New Hampshire, and extends into the lower elevation slopes of major valleys in the White Mountains. It has a “thin woods” appearance and is characterized by a variable and diverse mix of woody, fern, graminoid, and other herbaceous species, including numerous rich site species. This community shares some rich site species with rich mesic forests, but has a more open canopy, a sparser herb layer, and a species composition that reflects rockier and drier conditions. It supports certain species preferential to talus or dry-rich rocky habitats, including numerous vines (lianas), and disturbance or open-site tolerant species that occupy gaps.

Soils consist of rocky till or talus from cliffs above and have a dry-mesic to mesic moisture regime with inclusions of wetter and drier microhabitats. Source bedrock types are intermediate to basic, yielding elevated levels of calcium and/or other base-cations and moderately enriched soil conditions. Some examples occurring on otherwise acidic talus are enriched by minor base-cation bearing inclusions. Organic and mineral colluvium also contributes to enrichment.

Characteristic Vegetation: Tree canopy dominants usually include Acer saccharum (sugar maple) and Quercus rubra (red oak), with lesser amounts of Tilia americana (basswood), Fraxinus americana (white ash), Ostrya virginiana (ironwood), Betula lenta (black birch), Acer rubrum (red maple), and occasionally Betula alleghaniensis (yellow birch) and B. papyrifera (paper birch). Softwoods are sparse or absent. Understory shrub and herbaceous species that prefer enriched conditions and differentiate this community from till or talus forests on acidic soil include Cornus rugosa (round-leaved dogwood), Saxifraga virginiensis (early saxifrage), Geranium robertianum (herb Robert), Juglans cinerea (butternut), Asplenium platyneuron (ebony spleenwort), Aralia racemosa (spikenard), Oryzopsis racemosa (blackseed rice-grass), Clematis virginiana (virgin’s bower), Toxicodendron radicans (poison ivy), Corylus cornuta (beaked hazel-nut), Asarum canadense (wild ginger), Rubus odoratus (purple-flowering raspberry), Carex rosea/radiata (rosey sedge), C. platyphylla (flat-leaved sedge), and C. sprengelii (long-beaked sedge). Potential rare species of rich sites include Arabis canadensis (sickle-pod), A. laevigata (smooth rock-cress), Geranium carolinianum (Carolina cranesbill), Cardamine concatenata (cutleaf toothwort), Adlumia fungosa (climbing fumitory), and Carex aestivalis (summer sedge). Milium effusum (millet-grass) is a possible uncommon species that may be found at rich sites.

Species characteristic of both acidic and enriched soils include Dryopteris marginalis (marginal wood fern), Polypodium virginianum (rock polypody), Parthenocissus quinquefolia (Virginia creeper), P. vitacea (grape-woodbine), Polygonum cilinode (fringed bindweed), Celastrus scandens (American bittersweet), Solidago caesia (blue-stemmed goldenrod), Smilacina racemosa (false Solomon’s seal), Ribes spp. (gooseberries and wild currants), Deschampsia flexuosa (common hairgrass), and Fragaria vesca (wild strawberry). Examples in the White Mountain region may have the northern plants Arabis drummondii (Drummond’s rock-cress), Clematis occidentalis (purple clematis), and Polystichum braunii (Braun’s holly fern).

Talus and rocky till slopes are inherently diverse and variable, but they do exhibit some fairly discrete differences related to the overall soil moisture status, resulting in distinct dry-mesic and dry variants:

1. Dry-mesic variant: 
   In dry-mesic rock and talus areas, herbs, vines, and ferns may form a lush understory with a glade-like or “fern-glade” appearance with a relatively sparse shrub layer. Mesic conditions can occur in gullies or other runoff areas, on lower portions of the talus, or at the base of the cliff. Ferns, sugar maple, and ash are often higher in cover in this variant, with oak somewhat less frequent. The more mesic nature of this variant is indicated by the following rich-site species: Erythronium americanum (dogtooth violet), Adiantum pedatum (northern maidenhair fern), Caulophyllum thalictroides (blue cohosh), Eupatorium rugosum (white snakeroot), Cardamine diphylla (broad-leaved toothwort), Allium tricoccum (wild leek), Dicentra canadensis (squirrel-corn), D. cucullaria (Dutchman’s breeches), climbing fumitory, Deparia acrostichoides (silvery spleenwort), Panax quinquefolius (ginseng), and many others. Other dry to mesic site ferns include Athyrium filix-femina (lady fern), Dryopteris intermedia (intermediate wood fern), Polystichum acrostichoides (Christmas fern), the very rare Diplazium pycnocarpon (narrow-leaved spleenwort), and, in northern examples, Braun’s holly fern. Numerous broad-leaved forest sedges (Laxiflorae group) may be present including flat-leaved sedge and C. plantaginea (plantain-leaved sedge).

2. Dry variant: 
   Drier portions of till and talus slopes or those that are only seasonally moist tend to have species characteristic of both acidic and rich soils on talus slopes (e.g., marginal wood fern, rock polypody, Virginia creeper) as well as those that prefer dry conditions. Red oak and ironwood may be more prominent and sugar maple less so. The understory herb layer is generally more sparse. Rich site species that appear to be somewhat tolerant of drier or seasonally moist conditions include blackseed rice-grass, Woodsia ilvensis (rusty woodsia), early saxifrage, poison ivy, Carex rosea (star sedge), Drummond’s rock-cress, and herb Robert. Species characteristic of drier talus (yielding both acidic and enriched soils) that are sparse or absent on moist talus include common hairgrass, Aralia hispida (bristly sarsaparilla), Cardamine parviflora (narrow-leaved bitter cress), Antennaria plantaginifolia (pussy-toes), Hystrix patula (bottle-brush grass), Oryzopsis asperifolia (rough-leaved rice-grass), Pteridium aquilinum (bracken), Carex lucorum or C. pensylvanicum (distant and Pennsylvania sedges), C. tonsa var. rugosperma (shaved sedge), Chenopodium boscianum (Bosc’s pigweed), C. album (lamb’s quarters), Hedeoma pulegioides (American pennyroyal), and Elymus trachycaulus (wheatgrass).

Good examples of this community occur at Rattlesnake Mtn. (Rumney), West Rattlesnake Mtn. (Holderness), Bald Knob (Moultonborough), Whites Ledge (Bartlett), and Devil’s Slide (Stark).

Rich red oak
rocky woods often occur as part of a larger rich north-temperate talus/rocky woods system.

Rich red oak rocky woods below the ledges at West Rattlesnake Mtn. (photo by Ben Kimball for the NH Natural Heritage Bureau)
Rich red oak rocky woods below the ledges at West Rattlesnake Mtn. (photo by Ben Kimball)

Rich red oak rocky woods below the ledges at West Rattlesnake Mtn. (photo by Ben Kimball)
Rich red oak rocky woods below the ledges at West Rattlesnake Mtn. (photo by Ben Kimball)

Rich red oak rocky woods in New Hampshire (photo by Dan Sperduto)
Rich red oak rocky woods
 in New Hampshire (photo by Dan Sperduto)

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