Rocky outcrops, biodiversity hotspots

Bedrock outcrops in the Midwest are local biodiversity hotspots: Its the geology--the geoecology.

Black Hand Sandstone outcrop, southern aspect, Hocking County, Ohio. A harsh vertical environment tackled by epilithic (rock surface) life forms, and more.

Outcrops along steep ravines and in monumental rocky landscapes force openings in forest canopies revealing the foundations of terrains and opening unique habitats; ecotones in the vertical dimension, landforms offering novel opportunities for unique living things--outcrop ecosystems. Bedrock controls include: increased surface area, increased harborage in rocky openings, extremes of moisture and dessication from moist low seeps to elevated sun-parched rock faces, recesses and aspects permanently shaded, groundwater chemistry not buffered by soil, and groundwater's energy inputs and impacts--warming and increasing humidity in winter and evaporative cooling in summer.

Erosion-resistant rock outcrops obtain steep inclines that surrender soil cover, litter and duff, to unrelenting gravity. Even as a cliff face slowly weathers and erodes, newly exposed bedrock renews the outcrop. New cracks and crevices, cavities and rocky shelters open. Outcrops outlast forests and stream channels, they sustain lasting habitats in changing modern landscapes. Outcrops offer abundant stable spaces and surface area supporting life processes, they are riddled with openings exploited by living things dependent upon access to geothermal energy and moisture or shelter. Outcrops open epilithic (rock surface) niche opportunities. Outcrops catalyze biodiversity. Outcrops are ecosystem multipliers.

Black rat snake escaping September heat on a double-stack Eastern Phoebe nest in a recess under a nature bridge formed by Sharon Sandstone, Pike County, Ohio.

Bedrock outcrops offer endolithic (interior rock) niche opportunities exploited by diverse microorganisms, from algae living in tiny spaces in the rock surface, to microorganisms in deep rock, to extremophiles--bacteria species living among sand grains millimeters below the surface of sun-baked southern rock exposures. Endolithic life is barely explored by modern investigators. The sandstone image below captures more than a spider. The gray, green, and blue hues and the bits and flakes that are not sand grains, are living things; algae, fungi, lichens, plus unseen microorganism diversity. The surface abundance only hints at the subsurface abundance. Extremophile bacteria have been found deep inside rocks of many types. The stability of geothermally supported micro-ecosystems in bedrock interiors and bedrock recesses support micro-biodiversity hotspots. The impact of endolithic life on larger ecosystem elements; plants, insects, animals, is a new field of inquiry. Does endolithic bacteria fuel independent shallow rock ecosystems that interact with exterior sun-supported ecosystems?

Cobweb spider anchored with its egg sack inside a pebble cavity in a Sharon Sandstone outcrop in January, Lake Katherine State Nature Preserve, Jackson County, Ohio.

Groundwater, along with the thermal energy impacts it holds, moves under gravity toward local base levels intersected by bedrock outcrops. Permeable rock delivers the moisture and its energy impacts to bedrock openings and outcrop surfaces through pour spaces in permeable layers and zones, through cracks and crevices and through rock joints, the large cracks that fissure entire bedrock formations. Soft permeable layers conduit moisture to the rock surface while tightly cemented resistant layers impede water movement and protrude from the outcrop face, lending surface texture and casting shade over moist recesses, large and small.

Long-tailed salamander prowling a moist sandstone ravine ledge during a warm morning in Wayne National Forest.

Conserve bedrock outcrops,* insist that forest buffer zones surround outcrops in logged landscapes, insist that substantial undisturbed bedrock buffers surround outcrops near anthropogenic bedrock exposures in quarry operations.

*Bedrock is revealed in naturally occurring outcrops along streams, ravines, and promontories, and by anthropogenic exposures excavated along roadsides and railroads and in quarries. Naturally occurring outcrops support outcrop ecosystems.