Threats to Nature

History Leading to Our Efforts at Restoration, Research, and Education.

Denver Zoological Foundation at Rio Mora National Wildlife Refuge dedicated to preserving the Southwestern ecological heritage. The ranch contains 4,500 acres in south-central Mora County, and it is at 6,700 to 7,000 feet of altitude. The canyon along the Mora River is up to 300 feet deep. Major habitat-types on the ranch are western Great Plains short-grass prairie, pinon-juniper (Pinus edulis / Juniperus spp.) and oak (Quercus ssp.) woodland, ponderosa pine (Pinus ponderosa), and a five-mile long riparian corridor of the Mora River. Six side canyons feeding the river contain permanent seeps, springs, and ponds, and some ephemeral water holes. Riparian areas represent less than 1% of the total area in the Southwest, but about 75% of vertebrate life depend on these areas for food, water, cover, and movement (Bogan et al. 1998).

The need for ecological restoration in the region is urgent.  Thompson (2006-2007: 10) stated “In spite of the evolutionary history of grazing [on the Great Plains], domestic livestock have had a negative impact upon the shortgrass prairie.”  That negative impact is clearly visible.  Native grasses have declined while less palatable shrubs and weeds have increased.  Erosion and soil compaction have increased.  Keystone species have been persecuted, and their decline has produced a degradation of biodiversity across trophic levels.  Exotic species thrive in disturbed areas.  Fencing, roads, and grazing in riparian areas have taken an ecological toll.

Following the boom in cattle production during the 1880s, arroyos began forming in the 1890s.  Those arroyos continue to grow today.  Arroyos also form because of erosion from poorly designed roads and abandoned irrigation ditches.  When soils dry, plant productivity, diversity, and abundance declines; evaporation increases; run-off cuts erosion gullies into the soil; soil moisture decreases and the water table subsequently lowers (Zeedyk and Jansens 2004). This reduces productivity for native terrestrial and aquatic fauna (Tennesen 2008).  In particular, a lower water table means the loss of springs, seeps, playa water, and prairie streams.  Subsequently, run-off increases, dumping sediment into the rivers (Bogan et al. 1998; Allen 2003).

Piñon /juniper woodlands and yucca have advanced onto the grasslands, and they have also increased in density.  This reduces diversity and abundance of grasses, increases erosion, and reduces infiltration rates of moisture (Gedney et al. 1999).  Millions of acres of grasslands have thus been lost throughout the western United States (Jacobs et al. 2002; Tennesen 2008).  Globally and in North America, grasslands are a highly threatened ecosystem (Primack 2002).  When piñon/juniper/yucca out-compete grasses on a slope, it leads to arroyo formation and lowered water tables.  Shifts from grasses to woodlands are caused by climate (drought), heavy livestock grazing that reduces grasses, and changes in the fire regime (Dick-Peddie 1993; Arno and Fiedler 2005, Shinneman and Baker 2009).  Drought speeds the conversion of grasses to woodland through competition for water (Arno and Fiedler (2005). We are currently investigating another mechanism of shrub and tree encroachment onto grasslands through a graduate student at NM Highlands University: the absence of the native mega-herbivore, bison (Bison bison).  By breaking trees and shrubs, bison may have played a keystone role in keeping grasslands in grass, similar to elephants in Africa.

Fire suppression broke another interactive link between grazers and a key natural process.  Fire increases the diversity and density of grasses (Arno and Fiedler 2005).  Both Pfeiffer and Hartnett (1995) and Brown and Stuth (1993) provided evidence that grazing management alone does not replace the ecological function of fire.

Old-style forms of livestock management such as killing predators and competitors, fencing, road-building (another cause of erosion and arroyos), introducing exotic plants as forage, using chemicals, altering fire regimes, and grazing in riparian areas took an ecological toll (Freilich et al. 2003).  Keystone species have been eliminated from large areas of their former range because they compete with cattle for grass (prairie dogs, Cynomis spp.), impede attempts at irrigation (beavers, Castor canadensis), or because they are predators who can view cattle as prey (wolves, Canis lupus).  Keystones are highly interactive species that contribute greatly to ecological and evolutionary functions.  Even though individuals of those species still persist at various locations across their historic range, they are no longer abundant enough or distributed widely enough to exert their ecological function (Soulé et al. 2005).  That causes a series of indirect effects that ripple through trophic levels, affecting life-forms that seem distantly removed from the keystone (Terborgh et al. 1999; Miller et al. 2001; Soulé et al. 2005).

In a brief summary, to achieve maximum short-term profits, humans needed to dominate nature.  The grassland ecosystem was simplified to give humans more control.  Competitors and predators were eliminated, processes were changed, and interactions were broken.  The grasslands evolved with grazing (in some places quite heavily), but not with only one grazer.  So, those short-term profits came at a cost to long-term resilience of the western grasslands.  Uniform utilization is counter to conservation of biodiversity, which requires patchy grazing, species interactions, and a landscape matrix of habitat types (Truett et al. 2001).  The mind-set of domination, and the economic discount rate, worked against sustainable use of the prairie.

The riparian area along the Mora River has been eroded and in some places the natural meander of the river has been altered.  In some places, the entire river channel was moved for agriculture.  Willows (Salix spp.) and cottonwood (Populus spp.) are less abundant than they would be in an undisturbed area. Willows cover about 25% of the riverbank, whereas cottonwoods no longer exist as a gallery forest.  Cottonwoods were once actively eliminated because ranchers thought they took too much water from the river.  Cottonwoods now exist in small and isolated stands, or as individual trees.

In the Mora River, oxygen levels have decreased, temperature has increased, sedimentation has increased, there is non-point and point pollution, exotic trout have been introduced, and the native Rio Grande cutthroat has been eliminated.  The river is presently on the verge of changing from a cold-water fishery to a warm-water fishery.

Recently, subdivision of ranches for second homes and small ranchettes has fragmented and reduced habitat for wildlife by fences, roads, fire suppression, persecution of predators, human pets, and human activity (White 2008).  Because of our proximity to the wealth of Santa Fe, and the natural beauty of the Mora River Watershed, our area is very vulnerable to habitat destruction by subdivision.  Fifteen years ago, a developer planned subdivision on part of the Wind River Ranch, but Eugene and Clare Thaw saved the land by purchasing it.

The threat of oil and gas exploration by hydraulic fracturing has moved into the Las Vegas Basin.  Oil and gas explorations have had severe impacts on wildlife in the Powder River Basin and the Green River Basin of Wyoming, including water pollution (both ground water and the aquifer), destroyed wildlife habitat, interrupted migration routes, roads, poaching, and electrocution/collision of birds with power-lines.

The degradation of nature can also threaten human livelihoods, particularly in the long-term.  Mora County is rural and poor.  About 50% of the children in Mora County live below the poverty level; Mora County is the 17th poorest county in the nation (Mora County Land Use Management Plan, in prep).  At the Rio Mora National Wildlife Refuge, we hope to nurture a sense of place through the restoration of landscapes and increase ecological awareness toward responsible land-use, including connectivity among landscapes.  Erosion, lack of water, and declining health of grasslands are issues of concern in our region, and 80% of New Mexicans agree that restoration of such ecosystems is important (NM Game and Fish 2006).

We believe that species diversity and landscape matrices can be restored, at least at smaller scales.  If we continue to work within the historic land-use paradigm, we will continue to produce the same deleterious conditions we have seen over the last century—degraded soils, loss of water, loss of key species / processes.  The Wind River Ranch offers an excellent location to recreate the native prairie and riparian system.  There is educational benefit for youth in seeing native species in native conditions.  There are research opportunities to investigate restoration techniques.  Finally, having a place that is a refugia for nature offers the native system with native species that can be used as a control by which we can forever measure the effects of various management practices based on anthropocentric desires.

There is no time to waste.  One of the recent developments of science is recognition of how non-linear responses and thresholds affect habitat degradation and wildlife management.  Nature does not exist in a steady state, but continuously varies within certain bounds, and the species and systems have adapted over time to the range of variability in their particular region.  When the range of variation is pushed beyond the threshold of adaptive boundaries, a system can decline at an exponentially increasing rate.  Once thresholds are crossed, synergistic effects make it increasingly difficult to restore a system.

For example, an exotic plant species like cheat grass (Bromus tectorum) can change the chemical composition of the soil, and also the fire cycle, to something that favors cheat grass and works against the native species.  Thus simply replanting the native grasses may fail.  As another example, an area with few native grasses and dense stands of shrubs because it was over-grazed during the Dust Bowl, may show little or no ecological response after decades of rest.  Soils, fire cycles, species diversity, and competitive interactions have already been changed (Bestelmeyer et al. 2002).  And, restoring a keystone species may not increase species diversity if the other species associated with the keystone have already disappeared from the region.  Thus the longer we wait, the harder (and more expensive) ecological restoration becomes.  Waiting too long means that we may have to measure recovery in geological time frames.


Allen, C.  2003.  Where have all the grasslands gone?  Pp. 119-126 in Forging a West that works.  The Quivira Coalition, Santa Fe, New Mexico, USA.

Arno, S.F. and C.E. Fiedler.  2005.  Mimicking nature’s fire: Restoring fire-prone forests in the West.  Island Press, Washington DC, USA.

Bestelmeyer, B., J. Brown, and K. Havstad.  2002.  Grazing in complex environments—the details matter.  Pp. 1-6 in The new ranch at work: Proceedings of the 2002 Quivira Conference.  Quivira Coalition, Santa Fe New Mexico, USA.

Bogan, M.A., C.D. Allan, E.H. Muldavin, S.P Platonia, J.N. Stuart, G.H. Farley, P. Mehlhop, and J. Belnap.  1998.  Southwest.  Pp. 543-592 in Status and trends of the nation’s biological resources.  Eds. M.J. Mac, P.A. Opler, C.E. Puckett Haecker, and P.D. Doran.  U.S. Geological Survey, Washington DC, USA.

Brown, J.R. and J.W. Stuth. 1993. How herbivory affects grazing tolerant and sensitive grasses in a central Texas grassland: integrating plant response across hierarchical levels. Oecologia 67: 291-298.

Dick-Peddie, W.A.  1993.  New Mexico Vegetation; Past, present, and future.  University of New Mexico Press, Albuquerque, New Mexico.

Freilich J.E., Emlen J.M., Duda J.J., Freeman D.C., and P.J. Cafaro.  2003.  Ecological effects of ranching: A six point critique.  BioScience 8:759-765.

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Kotliar, N.B. et al.  1999.  A critical review of assumptions about the prairie dogs as a keystone species.  Environmental Management 24:177-192.

Miller, B., B. Dugelby, D. Foreman, C. Marinez del Río, R. Noss, M. Phillips, R. Reading, M.E. Soulé, J. Terborgh, L. Willcox.  2001.  The importance of large carnivores to healthy ecosystems.  Endangered Species UPDATE 18:202-210.

Miller, B. et al.  2007.  Prairie dogs: an ecological review and current biopolitics.  Journal of Wildlife Management 71: 2801-2810.

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Pfeiffer, KE and DC Hartnett. 1995. Bison selectivity and grazing response of little bluestem in tallgrass prairie. Journal of Range Management 48:26-31.

Primack, R.  2002.  Essentials of conservation biology.  Sinauer Associates, Sunderland MA.

Shinneman, D.J. and W.L. Baker.  2009.  Historical fire and multi-decadal drought as a context for piñon-juniper woodland restoration in western Colorado.  Ecological applications 19: 1231-1245.

Soule, M.E., J. Estes, B. Miller, and D. Honnold.  2005.  Strongly interacting species: Conservation policy, management, and ethics.  BioScience 55: 168-176.

Sponholtz, C.  2005.  Agro-ecological Restoration.  M.A. Thesis, Prescott college, Prescott, Arizona.

Tennesen, M.  2008.  When juniper and woody plants invade, water may retreat.  Science 322: 1630-1631.

Terborgh, J., J. Estes, P. Paquet, K. Ralls, D. Boyd, B. Miller, and R. Noss.  1999.  Role of Top Carnivores in Regulating Terrestrial Ecosystems.  Pp. 39-64 in Continental Conservation: The Science of Continental Scale Reserve Design.  (Eds.) M. Soulé, and J. Terborgh.  Island Press, Washington DC, USA.

Thompson, B.C.  2006-2007.  New Mexico Department of Game and Fish Landowner Incentive Program Tier 2 Grant Proposal 2006-2007.  New Mexico Department of Game and Fish, Santa Fe, New Mexico.

Truett, J.C., M. Phillips, K. Kunkel, and R. Miller.  2001.  Managing bison to restore biodiversity.  Great Plains Research 11: 123-144.

White, C.  2008.  Revolution on the range: The rise of a new ranch in the American West.  Island Press.  Washington D.C.

Zeedyk, B.  2004.  An introduction to induced meandering: A method for restoring stability to incised stream channels.  The Quivira Coalition, Santa Fe, New Mexico USA.

Zeedyk, B. and J. Jansens.  2004.  An introduction to erosion control.  The Quivira Coalition, Santa Fe, New Mexico USA.