Ecotone (Wind Cave National Park)

Wind Cave National Park is an instant anomaly: a celebrated firescape on land preserved for its subterranean caverns.  What makes its fire scene compelling is the almost perfect balance between mixed-grass prairie and ponderosa pine forest.  What makes its fire story significant is how that ancient quarrel played out during America’s fire revolution.  Its biogeography makes Wind Cave a classic ecotone.  Its evolving fire practices made it a historical one as well.[i]

The landscape works, ecologically, to keep that balance between prairie and ponderosa.  The park lies on the southeast, lee side of the Black Hills, windy but not too windy; storms break on the north and west.  The landscape burns frequently, but not too frequently; perhaps 10-12 years on average, ranging from two to 34.  Its fires are large, but not too large; 600-6,000 acres within the boundaries.  At 28,500 acres the park is larger than its fires.[ii]

The fires come routinely enough to thin out pine thickets and kill pockets of mature trees, but not hard and often enough to abrade the forest away.  In the lowlands to the east the scene is grassy, a fire steppe grading into a pine savanna; along the western summits, it thickens into a forest with a serviceable understory of grass.  The pine tumble down the ridges like a biotic rockfall into woody talus and stringers and scattered clumps.  A serrated, even fractal fringe etches the frontier between mix-grass prairie and ponderosa forest.  Park fire staff estimate the relative ratio of grasses to trees as 50:50.

What further checks the fires is a full complement of indigenous fauna that compete for, break up, and sculpt the fire-bearing grasses.  The park was created in 1903 to celebrate an underground curiosity.  But its surface landscape, an intact prairie, was ideal for restoring grassland fauna.  In 1912 a game preserve, under the direction of the U.S. Biological Survey, was established adjacent to it and stocked with bison, elk, and pronghorn.  The preserve was subsequently transferred to park jurisdiction.  The land already held most prairie mammals including extensive prairie dog towns.  For predators it had cougars, wildcats, and (later, introduced) black-footed ferrets.  All it lacked were grizzlies and wolves.

The outcome is one of the purest expressions of a prairie-pine ecotone anywhere.  The Black Hills are a western firescape, but plucking them onto the Plains makes their flanks into a hybrid in which grassland and forest spill into each other.  The resulting biota is probably as close to pre-settlement conditions as anything in the Great Plains.  The landscape remains an ecotone.

§ The last landscape-scale fire in the region occurred in 1881 before the usual suspects – logging, grazing, fire suppression – crashed the system.  That was the western side (the woody, so to speak) of the park’s historical ecotone.

Its grassy, eastern side, as it were, spared the park itself from the worst excesses.  It was a small polygon in the regional matrix, was never logged over, shed its livestock grazing between 1906 and the early 1930s, never had a serious capacity to fight fire until the CCC arrived in 1933, and then, with lightning kindling many starts, its rich grasslands meant fires could burst through for a burning period or two before the winds paused or crews could muster.  Its largest recorded lightning fire occurred in 1961 (1,156 acres).  A year after the Leopold Report a cigarette-kindled blaze burned 5,468 acres in the park, and 13,000 overall.

In brief, the land never lost its fires, or at least kept enough to prevent the biota from spiraling toward one extreme or another.  When the fire revolution arrived, the park had anchor points from which to reintroduce prescribed burning.  It also had a cornucopia of advantages: nearly every feature of its circumstances favored keeping fire.  It still had ample grass, with few invasives.  It had a charismatic creature, the bison, that fed on grass.  It held no significant cultural artifacts that fire might impact.  It had no WUI.  It housed no threatened or endangered species.  It faced no concerns over smoke.  It was mostly bordered by public lands; its private-land neighbors lay within the Black Hills Fire Protection District; and in 1973 it joined the Interagency Prescribed Burning Coordination Committee, a move that helped overcome isolation and problems of institutional scale.  It boasted a landscape with a high degree of ecological integrity and resilience, one able to absorb wildfires into its fire management regimen.  Its signature feature, Wind Cave, lay well below fire and smoke.  It had access to research capabilities from the Forest Service and South Dakota State University.  Its governing bureau, the National Park Service, was keen to reinstate fire, which it saw as a natural process, and was tolerant of fire’s potential interaction with other disturbances such as mountain pine beetle.

Wind Cave had political and geographic space in which to act.  It was big enough to do something, yet not big enough to attract unwanted attention.  It had none of the killer-app issues that flattened many programs.  It was not a celebrity landscape guaranteed to draw quirky critics.  It straddled a historical ecotone in which its fire program might side with the revolution or elect to dawdle.  It lay with Wind Cave to choose.

§  It chose grass and fire.  In 1973 it commissioned research under an agreement with the U.S. Forest Service and South Dakota State University, and commenced experimental burns, which seamlessly segued into an operational program that balanced the ecotone between woods and prairie.  It moved choice into action, and then it has continued the program for 40 years.  That experience (and relative heft) has made Wind Cave the center of fire operations for seven NPS sites throughout the Black Hills and Badlands.

However auspicious the circumstances, that transition did not happen on its own.  Conditions were favorable only if someone acted on them; left to themselves, the environmental pressures favored the woods, and bureaucratic pressures, the choice of making no choice.  On one side of history’s ecotone stretched the relentlessly encroaching past of fire exclusion, and on the other, a still open future of fire restoration.  Many sites, big and small, both the known and the obscure, found themselves at that similar edge, and chose poorly or more often simply found ways to dally and fret until the forest had pushed the fringe of history back into the past.  A few sites picked up the torch, opened up new grassland, but then faltered in trying to keep the torch lit, and the woods returned.

Wind Cave chose the grass, it chose early, and it has kept choosing.  The rest, as they say, is history – but history only if we appreciate how choosing the future becomes the past.

 Steve Pyne

April 2012 / [pdf]

 Acknowledgements

Cody Wienk orchestrated an exceptionally productive visit, which Dan Swanson, Eric Allen, Amy Symstad, and Al Stover turned into a tutorial and field trip.  The park is unusually rich in information, which the staff generously made available.  As usual, how they see the land they manage is not how I see it, but interpretation is my charge – one I think an agency dedicated to public interpretation can understand if not appreciate.  My thanks to all.

 



[i] The park has a wonderful library of data and reports.  Among the most useful I found were: S. Bone and R. Klukas, “Prescribed Fire in Wind Cave National Park,” unpublished report (Oct 27, 1988); Deane M. Shilts, “Experimental Burning in Wind Cave National Park,”  unpubl. report (February 18, 1976); Peter M. Brown and Carolyn Hull Sieg, “Historical Variability in Fire at the Ponderosa Pine – Northern Great Plains Prairie Ecotone, Southeastern Black Hills, South Dakota,” Ecoscience 6(4) (1999):539-547; and Wind Cave Draft Fire Management Plan (2005), which includes a good historical summary.

[ii] In 2012 the park acquired an additional 5,300 acres from a former elk ranch.  These new acres are not part of the park’s past, but do belong to its future.

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