Basic Oak-Hickory Forest Community

I was charged with performing a rare plant survey for the federally endangered Harperella Ptilinium nodosum, also known as Piedmont Mock Bishopweed, an obligate (OBL) wetland plant that likes rocky riverbeds, rocky and gravelly shoals and sandbars, along sunny streams, and often times in the water or along the edge of the water.  Harperella’s endangered status means it is protected by both federal and state endangered species laws, and the U.S. Army Corps of Engineers and Virginia Department of Environmental Quality must consider potential impacts to this species before issuing permits to impact wetlands and other jurisdictional waters.

Harperella flowers are reminiscent of tiny-sized Queen Anne’s Lace, and which flower from late July through August.  This small, endangered perennial member of the carrot family lives along larger rocky creeks in Virginia and Maryland.  The field survey “window” for harperella is open from July 1 to September 30.  Our field work was performed on July 19, 2017 and July 26, 2017, by Mark Burchick, Leslie Wood and Bill Sipple, PhD.  Bill is a long-time friend, outstanding botanist/teacher and author of the 1989 Federal Inter-Agency Manual for Wetland Delineation.

Our site is a 400-acre tract in Prince William County, Virginia, and harperella has historically been observed on the nearby Aquia Creek at Quantico Marine Base, the Potomac River and the C&O Canal.  The U.S. Fish & Wildlife Service recommended the survey through iPAC, as our site may have suitable habitat as predictive models indicate that habitat could be present, and hence the need for survey.

We did what is known as a Presence/Absence Survey, and we broke down our habitat areas as being adequate, marginal or poor, whereby adequate habitat areas include perennial streams with significant rock outcrops and rocky shorelines with dappled lighting conditions.  We did not find harperella within the higher probability habitat during the two-day survey (statement of negative finding).

Our site occurs within a natural ecological community known as the Basic Oak-Hickory Forest. 

Mockernut Hickory, Carya tomentosa, with round-shaped nut husk.  (indicator species of Basic Oak-Hickory Forest Community)

Pignut Hickory, Carya glabra, with pear-shaped nut husk.  (indicator species of Basic Oak-Hickory Forest Community)

The principal habitat for Basic Oak-Hickory Forests in Virginia are dry uplands over basic igneous and metamorphic rocks.  Soils are typically circumneutral and have moderately elevated levels of calcium, magnesium, manganese, iron, and aluminum.  The term “basic,” refers high levels of base cation saturation rather than to soil pH, which analysis has proven to be a less reliable indicator of fertility and parent material.  Communities in this group are scattered to locally extensive throughout the Virginia Piedmont and on lower-elevation slopes of the northern Blue Ridge.

Overstory composition varies regionally, but is generally characterized by mixtures of white, northern red, black, chestnut and post oak, pignut and mockernut hickory, white ash and tulip poplar.  Hickories are especially abundant in these forests and may dominate some stands.  Dominance by tulip poplar usually follows heavy logging or other catastrophic disturbances.  Eastern redbud, eastern hop-hornbeam and flowering dogwood are common understory species.

Herb layers are typically patchy but species-rich and support diverse mixtures of both mesophytic and dry-site species.  In the spring, wildflowers such as cut-leaf toothwort, rue-anemone, star chickweed and spring beauty frequently carpet the ground layers of these oak-hickory forests.  The summer and fall aspect is dominated by forbs and grasses such as woodland agrimony, four-leaf milkweed, curlyheads, Bosc’s panic grass, naked-flowered tick-trefoil, bottlebrush grass, bedstraw, eastern Solomon’s-plume, rock muhly, goldenrod, yellow pimpernel, lesser horse-gentian and wood violet.

Basic Oak-Hickory Forests occupy more fertile soils and have higher species-richness and fewer ericaceous shrubs than do Acidic Oak-Hickory Forests.  They are distinguished from Montane Oak-Hickory Forests by their restriction to low-elevation habitats and corresponding composition consisting mostly of species that do not occur at higher elevations.  With a distribution in the Piedmont already restricted by limited available habitat, Basic Oak-Hickory Forests have also been reduced considerably by a long history of agriculture, conversion of hardwood forests to intensively managed pine stands, and urban development. Currently, oak recruitment is poor in many of these communities, and the often prominent component of white ash is under assault by outbreaks of the insect pathogen Emerald Ash Borer.  Some of the community types in this group can be considered uncommon or rare in Virginia.

The following are a few pictures of what was in flower during our two-day survey.

Chicory Cichorium intybus.

Hairy Ruellia Ruellia caroliniensis.

Blazing Star, Liatris squarrosa.

In Maryland, blazing star is classified as a highly state rare plant, is uncommon in Virginia and abundant on our job site.

Shrubby St. John’s-Wort, Hypericum prolificum.

Spotted Knapweed, Centaurea stoebe.

Slender Mountain Mint, Pycnanthemum tenuifolium.

Rose Pink, Sabatia angularis.

Dotted St. John’s-Wort, Hypericum punctatum.

Pink Wild Bean, Strophostyles umbellata.

Monkeyflower, Mimulus ringens.

Female Downy Woodpecker, Picoides pubescens feeding on Common Mullein, Verbascum thapsus.

I’ve never seen a Downy feeding on a mullein seed head before.

Swamp Milkweed, Asclepias incarnata.

Beaked Panicgrass, Panicum anceps.

Close-up of the beaked panicgrass inflorescence.

St. Andrew’s Cross, Hypericum hypericoides.

Wild Senna, Senna hebecarpa. 

Goldfinch, Spinus tristis.

Is this Goldfinch going to drink or bathe, with both ideas sounding refreshing on this nearly 100-degree day!

That’s a long reach for a drink.

Amanita jacksonii mushroom, which looked absolutely beautiful as it emerged from the forest floor.

Queen Anne’s Lace, Daucus carota.

Eastern Bottlebrush Grass, Elymus hystrix.  (indicator species of Basic Oak-Hickory Forest Community)

Close-up of Eastern Bottlebrush Grass inflorescence.  (indicator species of Basic Oak-Hickory Forest Community)

Squarrose Sedge, Carerx squarrosa.

Bosc’s Panic Grass, Dichanthelium boscii.  (indicator species of Basic Oak-Hickory Forest Community)

Note the wide leaf blade and node with long, downward-pointing hairs on the Bosc’s panic grass.  (indicator species of Basic Oak-Hickory Forest Community)

Developing Persimmon, Diospyros virginiana fruit, which should be ripe in September/October.

Alien invasive Johnsongrass, Sorghum halepense, inflorescence head.

Water Pimpernel, also known as Brookweed, Samolus parviflorus, which looks similar to water plantain Alisma subcordatum, and which is found in similar, saturated habitats.

Other plants that we observed in flower included inflated lobelia, heal-all, blue-eyed grass, smartweed’s, wild mint, deptford pink, ditch stonecrop, water plantain, black-eyed Susan, pennyroyal, hawkweed and trumpet creeper.

Although the 400-acre site is beautiful, it is loaded with adult and seed ticks and chiggers, with the chiggers reminding you of the site for weeks later, as one suffers from the bites.