Montalto Prickly Pear Habitat
Montalto Prickly Pear Community
©Devin Floyd
Albemarle County, Virginia
With a strong and chilling mountaintop wind
, fog lifting and sun dappled clouds racing by, we explored a very unusual habitat:
Catoctin Greenstone, Eastern Prickly Pear Cacti (
Opuntia humifusa
) community.
The prickly pear cacti in the larger Albemarle area is typically found on south facing and relatively horizontal rock outcrops. It also gravitates toward outcrops of granite, granulite, and related bedrock. These rocks are high in silica and decay to produce nutrient-poor acidic soils. The prickly pear cacti doesn't seem to mind. In fact, in keeping a tally of prickly pear sites in Albemarle County, all 5 have been on granite or granulite outcrops. Today I witnessed an abrupt shift in that trend.
Montalto reaches to the sky
at the north end of Carter's Mountain. It is part of a strip of Virginia land that was preferred by early plantation holders (ie., Madison, Jefferson, Monroe, etc). The bedrock holding up this land (a meta-basalt known as Catoctin Greenstone) decomposes into soil that is very high in nutrients (esp. Calcium). It has a high levels of base cations, which means the soil retains nutrients and makes them available to plants.
The nutrient-rich soils of Montalto
produce greater tree diversity here than at any other prickly pear habitat I've observed to date. It is likely that diversity is high in the herbaceous layer as well. (**Note: The site is maintained relatively treeless, and so we surveyed an outcrop in a forested area immediately next to it. Results are below).
Lat/Long.:
37.99949 / -78.464799
Elevation:
1272 feet
Size of the Habitat:
The site is roughly 35' x 95' (+/- 5 feet)
Aspect:
Relatively flat, mountain top. The prickly pear colony is most prevalent along the Southeast side of the outcrop, and the land slopes very gently toward the southwest.
Soils:
Soil/silt trapped in small cracks and pockets in and around the greenstone outcrop.
Bedrock: Central Blue Ridge anticlinorium.
Catoctin Formation - Metabasalt.
early cambrian-age rocks (570-600 million years old).
Conditions:
50 degrees (going up to near 60) and very windy. The ground is saturated after a night of rain. The prickly pear at this site is unusually dense
. I attribute this to the maintained lawn around it, giving it full access to sun, and high-nutrient soils.
Trees and Shrubs
(This list was observed at an outcrop area immediately to the SW of the prickly pear habitat. The prickly pear habitat is in a maintained clearing.)
Dominants
:
Chestnut Oak, Quercus prinus
Virginia Pine, Pinus virginiana
Honey Locust, Gleditsia triacantho
Eastern Redbud, Cercis canadensis
Other:
Black Oak, Quercus velutina
Scarlet Oak, Quercus coccinea
Black Locust, Robinia pseudoacacia
Red Cedar, Juniperus virginiana
Hackberry, Celtis occidentalis
Pignut Hickory, Carya glabra
Persimmon, Diospyros virginiana
White Ash, Fraxinus americana
Tulip Poplar, Liriodendron tulipifera
White Oak, Quercus alba
Other Flora noted:
Eastern Prickly Pear Cactus, Opuntia humifusa
Coralberry, Symphoricarpos orbiculatus
Non-native
flora
:
Japanese Honeysuckle, Lonicera japonica
Autumn Olive, Elaeagnus umbellata
Wineberry ,Rubus phoenicolasius
Barberry, Berberis sp.
The cacti fruit (sweet and fermenting this time of year) is a valuable food source for wildlife including rabbits, deer. box turtles, and coyotes.
Thank you, Justin and Peggy, for a wonderful mountain-top morning!
I recommend the following plants for potential additions to this unique habitat. They are all regional basic outcrop plants (list compiled by Lonnie Murray and Devin Floyd of the Albemarle Natural Heritage Committee):
cliff stonecrop, Sedum Glaucophyllum
pale corydalis, Corydalis sempervirens
Allegheny stonecrop, Hylotelephium telephioides
wooly lip fern, Cheilanthes lanosa
small flowered phacelia, Phacelia dubia
rock spike moss, Selaginella rupestris
wild pink, Silene carolina
fameflower, Talinum teretifolium
woodland stonecrop, Sedum ternatum
skullcap, Scutellaria integrifolia
red columbine, Aquilegia canadensis
North Garden Prickly Pear Habitat
Approximation #1
Lat/Long.:
37.9322, -78.6489
Elevation: 800'
Aspect:
Southeast facing, sparse woods.
Soils:
Soil/silt trapped in small cracks in the granulite outcrop provide the nutrients needed.
Bedrock:
Blue Ridge basement complex. Biotite-Muscovite Leucogranite Gneiss, Grenville-age rocks (1-1.1 billion years old).
note: there is a seam of Meta-gabbro very nearby; it is an ultra-mafic rock, and is the same outcrop that provides the substrate at UVA in Charlottesville.
Conditions:
drought conditions have persisted for over a month
. The summer saw
69 days with 90-degree-or-higher temperatures. Since August 1st, we have received not more than 1 inch of rai
n.
Trees and shrubs:
mockernut hickory
pignut hickory
chestnut oak
shortleaf pine
eastern red cedar
black locust
pawlonia
ailanthus
Virginia pine
black cherry
redbud
dogwood
serviceberry
huckleberry species
***Abundant saplings of redbud, chestnut oak, ailanthus, and cedar.
Other plants:
Eastern prickly pear
Unidentified:
a woody tick trefoil species
raspberry species
Eupatorium species
Cacti, Lobelias, Swallowtails, and Horsemint
It's been hot.
My solution?
...go west
...and up.... aahhh ... the Blue Ridge.
We really needed to get out of the house
, and so I took the girls on a field trip to visit some fun habitats...and cool air.
We started with what we thought would remind us of a desert...inspired by the heat: Eastern prickly pear cacti (Opuntia humifusa) habitat. This community of native plants thrives in cracks of an exposed sheet of granite in the Ragged Mountains of Albemarle County. (To date, I am aware of only four other sites in the county.) My five year old (Norah) could not resist "petting" the prickly pear pads. Well the nearly invisible teeny tiny needles (glochids) made her pay dearly...and yes, I gave her a firm warning in advance, reminding her of what happened the last time she caressed a prickly pear (in Tucson).
With needles and a renewed sense of respect in tow, we planned our next destination to a softer and cooler place.
We are budding butterfly watchers. The swallowtails currently have my attention, and the dark ones continue to mystify me. So, off we went again, this time to the land of butterflies...a Blue Ridge meadow. We soon arrived at Humpback Rocks, up along the Blue Ridge Parkway. The specific destination in mind was a meadow of milkweeds and campions. Immediately upon arrival, we were pleasantly surprised. Lobelia cardinalis was in full bloom in a nearby woodland understory, and the tiger swallowtails were taking full advantage of the nectar:
In our "target" field, the common milkweed was nearing the end of its bloom, but the butterflies were still sipping from campion flowers. Dominating the activity were spicebush swallowtail, monarch, and eastern tiger swallowtail. ...and a few milkweed tussuck moth caterpillars were trying to cross the road (see photo to right)!
As the milkweeds and dogbanes move into seed production, butterflies shift attention. This was made evident by the clouds of fluttering wings in a meadow we had previously overlooked...one dominated by Joe Pye weed, ironweed, Helianthus sp. and emerging goldenrod and thistle. This was the jackpot, but we had to watch from afar, as the patch of activity had a dense thicket of blackberry between us and it.After spending a couple of hours on the mountain, and with the evening approaching, we descended. The final destination was Ivy Creek Natural Area, for a look at the unfoldings in a lower elevation meadow. We opted for a single go-around on the field loop trail, and did it rather quickly...lightning was quickly approaching. In our rapid trot we hurdled a black rat snake, exchanged glances with an osprey , and spooked several deer....which spooked us. We also happened upon one of the more interesting wildflowers of late summer...Spotted horsemint, also known as spotted beebalm (Monarda punctata):
