Denver Zoological Foundation at Rio Mora NWR restoration and research projects include,
- Healing upland erosion in arroyos
- Pinon and Juniper Advancing onto Grasslands
- The Role of Bison in Grassland Restoration
- Prairie Dog Restoration
- Construction of a 35 acre floodplain on the Mora River
- Restoration along the Mora River
- Complete an Inventory of Flora and Fauna on the Wind River Ranch
- Broom Snakeweed
Erosion and arroyos are some of the most serious problems on the Rio Mora National Wildlife Refuge, as well as throughout the entire Southwest. The 1880s saw a boom in cattle across the west. New Mexico was no exception. In 1880, there were 137,000 cattle in New Mexico but by 1889 that number had increased to 1,380,000. Heavy grazing in the 1880s, combined with drought, denuded the landscape, and caused a large die-off in cattle. When the rains returned, there was little vegetation to hold the water. The run-off created arroyos and the subsequent erosion. A second cause of arroyos and erosion is the advance of piñon and juniper trees from the shallow soils of rocky slopes and onto the deeper soils of the grassland. The trees have advanced onto grasslands because of overgrazing, changes in fire regimes, and our early research indicates that the absence of bison may have helped that advance as well. The trees outcompete grass and if close enough together can denude the vegetation. If this occurs on a slope, it can create an arroyo. A third cause of arroyos and erosion is the improper placement of roads and abandoned irrigation ditches. Erosion worsens as the slope increases in angle. Where a grade suddenly becomes steep, or soil hardness changes, run-off creates a head-cut (Zeedyk and Jansens 2004). Head-cuts, in turn, increase the speed of run-off and that creates a system of positive feedback to worsen the erosion.
Erosion and lower water tables reduce the soil particles’ ability to hold water (Zeedyk and Jansens 2004; Sponholtz 2005). As a result, plant diversity and percentage of groundcover decrease, and that reduces the resilience to catastrophic events (Zeedyk and Jansens 2004). Eventually, the soils drain enough to lower the water table, destroying wetlands, cienegas, and springs. The soils also harden, so run-off increases, and that dumps sediment into the river. All of these effects reduce habitat for fish, plants, and wildlife with subsequent declines in species diversity. Seeps and springs are particularly vulnerable.
To return life to the land, soils must recover the ability to hold water (Zeedyk and Jansens 2004; Sponholtz 2005). Craig Sponholtz (Dryland Solutions) and Bill Zeedyk (Zeedyk Ecological Consulting) are consulting and leading the efforts to reverse the effects of upland arroyos upon the landscape. They read the flow of the land and design rock structures to reverse erosion. We ask volunteers to carry rock, branches, mulch, etc. and place them. We will also plant native seeds, trees, and shrubs to provide food and cover for wildlife.
Such efforts slow the flow of water and allow water to soften the ground (Zeedyk and Jansens 2004; Sponholtz 2005). This increases the amount of infiltration into the soil. The rock dams also raise the bottom of the arroyo and change the steep, narrow cut into a wide, shallow swale. The water table then rises, extends the reach of moisture farther into the grasslands, and reduces sedimentation in the river. When plants sprout on a degraded area, it slows air movement, provides shade, reduces evaporation, further slows water flow, holds soil in place, and the ground litter from plants adds organic content (Zeedyk and Jansens 2004; Sponholtz 2005). This structural change increases the health of the grassland and provides habitat for a host of vertebrates and invertebrates.
Many of the upland arroyos feed into canyons that connect to the river. These canyons at one time had wetlands, cienegas, springs, and natural ponds. In some canyons, those areas have dried. In other areas, they are at-risk. The work on arroyos will thus extend into the canyons to restore, enhance, and protect these wet areas, which are a source of life in the Southwest. Wetlands and riparian areas represent 1% of the geographic area in the Southwest, yet are used at some level by 75% of the wildlife (Bogan et al. 1998). According to the New Mexico State Wildlife Plan, about 90% of the wetland and riparian systems have been degraded in New Mexico (NM DG&F 2006).
We have completed about 175 one-rock dams in arroyos and canyons. Each dam averages about 3 tons of rock. In some places, the dams have raised the floor of an arroyo up to three feet and plants are sprouting. The dams have also raised the water table in canyons and there are now ponds in parts of those canyons that were formerly dry. Volunteers that have helped build these structures include interested citizens, members of the Albuquerque Wildlife Federation, members of the New Mexico Wilderness Alliance, Quivira Coalition, students at Santa Fe Indian School, MESA students from Robertson High School in Las Vegas NM, and University of New Mexico Service Corps. Rick Slater, of River Source, also used the structures to demonstrate watershed restoration techniques to teachers.
A Rock Structure to Restore Effects of Past Erosion
The work is sponsored by grants from the U.S. Fish and Wildlife Service Partners in Fish and Wildlife Program, the Landowners Incentive Program by the New Mexico Department of Game and Fish, the Denver Zoological Foundation, and the former Wind River Ranch Foundation. One thing that the Rio Mora NWR can offer is the opportunity to experiment with these techniques so that they can be improved.
An excellent graduate project awaits someone who is interested in quantifying the changes that occur following the placement of rock dams in arroyos and canyons. Independent variables would be soil type and rainfall per unit of time. Dependent variables to measure include geomorphology, sediment deposition, water quality, retention of soil moisture in adjoining grasslands, width to depth ratio of arroyos, diversity and density of vegetation, and changes in the vertebrate and invertebrate fauna. At present, monitoring is by photo points and not quantifiable. A graduate student could step in an begin monitoring immediately.
As juniper (Juniperus spp.) increases on western grasslands, diversity and abundance of grasses declines, erosion increases, and infiltration rates of moisture reduce (Gedney et al. 1999). This has caused desertification in eastern Oregon (Debroodt et al. 2009), and millions of acres of dry western grasslands have 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).
Romme, Floyd-Hanna, and Hanna (2003) classify piñon (Pinus edulis)/juniper vegetation into three categories: savanna, woodland, and forest. Savanna is a mix of piñon/juniper and grass that holds fewer than 320 trees per hectare, or 130/acre (Dick-Peddie 1993). Savanna is the transitional stage between grassland and woodland (Dick-Peddie 1993). 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). Plants with multi-level root systems, like junipers, have a distinct advantage. When there is rainfall, they can out-compete grass for the surface moisture via a layer of fine root-filaments 6 to 36 inches beneath the soil surface that can extend laterally three times the height of the tree (Foxx and Tierney, 1987). A halo effect of reduced grass density and diversity, reported by Arnold (1964) is clearly visible. When there is no rain, juniper can draw water from deep tap-roots (Tennesen 2008). Tap-roots of one-seed juniper can extend 160 feet below the surface (Foxx and Tierney, 1987).
Trees move water from roots to plant by opening pores in leaves, creating a vacuum through passages (tracheids). Junipers have the most drought-resistant system of water movement in any plant studied (Tennesen 2008). Nine to 35 western juniper trees per acre are enough to take all available moisture in an area receiving 13 inches of precipitation per year, drawing up to 30 gallons per day when adequate moisture is present (Debroodt et al. 2009).
The advantage of juniper in water-efficiency, combined with fire-suppression and overgrazing by domestic livestock, has allowed juniper to expand throughout the West from former fire-proof habitats (rocky, shallow soil sites) onto deeper soil sites that were formerly grasslands (Jacobs et al. 2002). Such tree expansion reduces penetration of water, reduces vegetation, and increases water run-off; the soil loses its ability to hold water, one of its most important characteristics (Jacobs et al. 2002; Zeedyk and Jansens 2004). 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. Approximately 75% of all wildlife depends on these water sources at some level in the Southwest. Piñon/juniper woodlands currently lose an average of one-half inch of soil per decade to erosion (Jacobs et al. 2002; Arno and Fiedler 2005). In Bandelier National Monument, such sediment loss in degraded woodlands is unsustainable (Jacobs et al. 2002).
There has been a fundamental shift from grasslands to wooded savannas in the last 125 years (Arno and Fiedler 2005). Predictions for increased drought following climate change will exacerbate the problem. If fragmentation proceeds in a random fashion, when 40% of an original habitat type is left, the patches become disconnected (Primack 2002). The isolated patches of that habitat-type then continue to shrink and become more distant from each other, with the invading habitat-type becoming increasingly more dominant. Loss of grasslands to expanding woodlands eventually eliminates the matrix of different habitat-types in an area and thus removes ecological boundaries that allow greater diversity of species to exist across a landscape.
Research at Bandelier National Monument showed that thinning piñon/juniper and distributing the slash was a very effective way to slow erosion and restore native grasses (Hastings et al. 2003). The slash/mulch increased soil moisture and created favorable microclimates for the re-establishment of forbs and grasses (Jacobs et al. 2002). Canopy reductions greater than 95% in Bandelier increased herbaceous cover by 3 to 7-fold (Jacobs et al. 2002). Such projects at Rio Mora NWR would also supply graduate students with research. Removing piñon and juniper from grasslands could test changes in sheet erosion, changes in soil chemistry, and compare methods of dealing with slash such as effects on soil of mulching, lopping and scattering, or removal for firewood.
Another graduate project could look at the soil moisture / water table changes due to tree removal. One study suggested that 17 inches of rainfall per year is necessary to see increased water yield in ephemeral ponds following juniper removal; there would only be increases in soil moisture below that level of rainfall (Hibbert 1983). But Debroodt et al. (2009) showed changes in soil moisture and water retention in an area with 13 inches per year.
This leads to the next effort in restoration, the effect of bison on grassland health.
While juniper expansion onto grasslands is furthered by drought, heavy livestock grazing, and changes in the fire regime, we propose another mechanism: the absence of the native mega-herbivore, bison. The return of the bison can reestablish health to a badly abused grassland system. It would reestablish hope, culture, and traditional values to western tribes. Our partnership with tribes around the bison is strong.
In a preliminary test, bison destroyed 90 per 100 of the yucca on the Rio Mora NWR compared to a mean 6.4 per 100 with cattle on five neighboring ranches (mostly Great Plains yucca or Yucca glauca). They typically horn the yucca up, although we have seen bison chewing on the leaves of young yucca. Similarly, bison have damaged 91 per 100 of the piñon/juniper on the Rio Mora NWR compared to a mean of 8.8 per 100 with cattle on five neighboring ranches. Those differences are statistically significant (p < 0.0001). On a grassland with neither cattle nor bison, but intermittent grazing by wild elk (Cervus elaphus), 4 per 100 yucca were damaged and 7 per 100 piñon/juniper were damaged. There was no statistical difference between this control grassland and the grasslands grazed by cattle.
Frequent low-level fires were characteristic of savannas and helped maintain grasses (Arno and Fiedler 2005). Bison may have also played a key part, like elephants in Africa, in keeping grasslands in grass. During the Pleistocene, grazing pressure was undoubtedly much higher than it is today. There probably wasn’t much grass to carry a good fire. On the other hand, there was a suite of browsers, like 5 species of proboscidians, camels, rhinos, ground sloths, etc., that probably reduced woody species on grasslands. Fire and megafauna may have also interacted. Damage to piñon/juniper causes an effusion of sap, which provides more flammable substance. This could help carry a fire when grasses are low.
In addition, to horning trees and shrubs, bison horn head-cuts and turn the dry waterfalls into slopes. When they horn chunks of sod, which fall to the base of the head-cut, the slopes become vegetated. That slows the flow of water and begins to heal effects of past erosion. It seems like bison can only be effective on head-cuts less than four feet high.
Relying only on bison for restoration may have its limits because many of the piñon/juniper are too big for either bison or fire to kill, and many of the headcuts are already too deep. We will have to help the process by physical manipulation. Once grasses are restored, we speculate that bison will play a role in keeping the grassland from becoming a woodland, thus preventing erosive forces from degrading the soils. And, while bison horn up yucca fairly quickly (a matter of months), it is harder to kill the trees. Those trees need return visits, although damage undoubtedly reduces a tree’s vigor. Nevertheless, it seems that bison may have played a role in keeping a grassland in good health by preventing the entry of trees.
To return life to a degraded grassland, soils must recover the ability to hold water. Restoring plants slows air movement, provides shade, reduces evaporation, slows water flow, holds soil in place, and the ground litter from plants adds organic content (Zeedyk and Jansens 2004). The piñon/juniper woodlands in Bandelier National Monument were too degraded to recover on-their-own (Jacobs et al. 2002). When disturbance exceeds a threshold, or tolerance level, the landscape undergoes non-linear structural and functional changes which prevent recovery to pre-disturbance condition by natural succession or rest (Davenport 1998).
Here we propose some predictions for bison research. Such research will increase knowledge of the role bison played in maintaining healthy grasslands. Most studies on bison have concentrated on genetics, autecology, and the history of bison decline. Because bison, like prairie dogs, were largely eliminated before there was interest or understanding of ecological roles, knowledge of bison/grassland interactions has been limited to grazing. From our pilot studies, that role appears to be much more. At present, students in the lab of Dr. Jesús Rivas (New Mexico Highlands University) are assessing the genetics of the bison on the Rio Mora NWR.
Bison and invasion of trees and shrubs onto grasslands.
We predict that bison activities will decrease the spread (recruitment/colonization rates) and abundance of piñon /juniper, yucca, and cactus (Opuntia spp.) onto grasslands.
All questions hinge on a foundation of how extensively bison affect tree and shrub invasion from rocky, shallow soils onto the deep soils of a grassland. We have preliminary data on bison and yucca and bison and piñon/juniper (see above). We compared the rates of damage by bison to trees and shrubs on the Wind River Ranch with rates of damage to trees and shrubs on five neighboring ranches with cattle. At present, Roger Griego is testing these ideas further as a Masters student at New Mexico Highlands University.
By working with tribes as they receive bison, we could make similar spatial comparisons, plus a temporal comparison of before and after bison are added. We will have plots on the Rio Mora NWR where piñon/juniper are removed, and we can quantify the interaction of bison with young trees and shrubs sprouting on the grassland.
Breaking trees and shrubs is a role for bison in grasslands that largely has been overlooked. Most comparisons between bison and cattle have focused on grazing activities and dietary overlap. That overlap is about 72% (Holochek et al. 2004) leading some to speculate that cattle can be a close ecological surrogate for bison. But it appears that bison interactions with grasslands extend far past the act of grazing, a factor that may influence surrogate status. We predict that the processes tested in this experiment will not be duplicated by cattle grazed at similar densities as bison.
Bison, vegetation, and soil.
We predict that the diversity of grasses and forbs (broad-leaved herbaceous plants), primary productivity, soil porosity, water retention, and soil retention will benefit from the activities of bison.
We can test this prediction by a series of experiments on treatment and control plots that will be selected by soil type, density of trees, and size of trees. Our small plots could be one hectare in size. We can also try to establish a paired-watershed approach of larger size (see Jacobs et al. 2002; Debroodt et al. 2009). The smaller (1-ha) plots will receive two treatments: one where trees are removed and branches are used for slash/mulch and one where trees are removed without slash/mulch. Treatments will be matched to a control plot where trees remain.
Vegetation and soil cover can be measured by permanent line transect routes. This would include pre-treatment as well as post-treatment monitoring. Quadrats of 1 m2 would be a method of measuring density and biomass of plants. Biomass would involve clipping, sorting by species, drying, and weighing to estimate productivity by species (Higgins et al. 2005).
In a functional ecosystem, water and nutrients are retained within the system; when run-off occurs, it is redistributed within the system—trapped and stored locally (Reid et al. 1999). Soil moisture can be measured directly by probes or indirectly by soil conductance of an electromagnetic energy pulse (Jacobs et al. 2002). Run-off can be measured by sediment traps, with sediment dried and weighed to measure sediment concentration (Reid et al. 1999) or by sediment bridges (Jacobs et al. 2002). This can be calibrated against rainfall per unit time. Soil nutrients can be measured following Jacobs et al. (2002)
A companion study on the Rio Mora NWR will look at the value of placing one-rock dams in arroyos and canyons to arrest gulley erosion in existing gullies. That study can measure the effects of bison-horning on headcuts at the start of gullies.
bison horned headcut one month after rain
A Piñon Pine Damaged by Bison Horning
Bison and wildlife
Grassland birds have been declining more severely than any other guild (Knopf 1993). We can sample birds in treated and control plots of the paired watershed using line transect or point counts (Lancia et al. 2005). Small mammals can be sampled in the paired watershed studies by means of live-traps and capture/recapture models (Lancia et al. 2005). Large mammals can be monitored by automatic cameras (Silveira et al. 2003). Arthropods can be sampled by direct capture and pitfall traps (Murkin et al. 1996). Monitoring wetland flora and fauna may be particularly interesting if soil moisture changes enough to affect the size and durability of seeps, springs, and ponds. The Denver Zoological Foundation is presently implementing such a study.
Bison and Climate Change.
We predict that increased grassland health will increase carbon sequestration at a level that will mitigate the effects of climate change.
Healthy grasslands can be a factor in removing carbon from the atmosphere, taking an average of 2,000 pounds of carbon per acre per year and putting it into the soil (an unpublished study of 1,500 grasslands by Rebecca Phillips; www.earthsky.org.radioshows/52522/grasslands-soak-up-carbon-to-slow-climate-change). According to a United Nations panel of experts, restoring health to 5 to 10% of the grasslands could mitigate 2 to 8% of the climate change effect by the year 2020 (FAO 2009). On the contrary, a study on 36 plots in northern California showed minimal impacts on grassland productivity from increased temperatures, precipitation, and carbon levels; they suggest that there may be little impact on climate change (Anonymous 2005). There is a clear need for more research into the role of bison on grassland health and global warming by measuring carbon levels in the soil of treated and control plots.
Interactions between bison and fire
First, there is no history of fire intervals in the area, and those intervals differed among piñon/juniper savannas, woodlands, and forests (Dick-Peddie 1993; Arno and Fielder 2005; Shinneman and Baker 2009). Fire history can be interpreted by taking piñon/juniper core samples from older trees. Timing of fires for maximum benefit to grasslands can be experimentally determined through controlled burns on selected plots.
Second, a graduate student could look at changes in vegetation density and diversity where bison and fire interact, bison graze alone, and fire occurs without grazing.
Bison are an integral part of the prairie grassland (Knapp et al. 1999; Truitt et al. 2001). The present grassland was formed largely due to the activities of prairie dogs and bison, two highly interactive species (Lott 2002; Kotliar et al. 2006). In their absence, grassland health declined, despite the introduction of another large grazer, domestic cattle.
While much of the difference between cattle and bison is due to management practices by humans, some differences are also due to evolution, morphology, and behavior. We propose that these differences give the bison an advantage over domestic cattle in the West. While there is a high overlap of diet between bison and cattle, the two species produce very different ecological effects (Freese et al. 2007).
Cattle are exotic to the U.S. and native to wetter areas, whereas bison evolved in the drought-driven conditions of the Great Plains. Indeed, bison are the only member of the Bovini line that is not represented at some level in the tropics (McDonald 1981). Perhaps because of this evolutionary history, cattle tend to stay closer to water than bison (Van Vuren 1983). Experiments have shown that grazing intensity of cattle is inversely related to the distance from water (Soltero et al. 1989; Holochek et al. 2004). Unless fencing, water development, or herding has prevented cows from staying near water, cattle have denuded the nearby grasses, trampled stream banks, harmed water quality, and degraded riparian areas (US GAO 1988; US EPA 1998).
Bison are more efficient with water than cattle. Bison typically come to get a drink once a day (Peden et al. 1974; Norland 1984). They leave after the drink, spending about an hour near water (Norden 1984; Wilkerson 2007). This may be due to predator avoidance strategies or the tight social structure of family groups within a larger herd (Wilkerson 2007). Having bison thus avoids the management costs of preventing riparian damage, and it also reduces demand on the declining aquifer.
Bison digest roughage better than cattle can, and bison thus can better utilize low-protein forage (Plumb and Dodd 1993; Truitt et al. 2001). This gives bison a competitive advantage over cattle on native grasslands. Being able to use lower quality forage allows bison to graze farther from the moist areas. Bison hides have better insulation than cattle, which makes their energy intake more efficient during winter. Bison can swing their heads to clear snow from the grass and can thus graze in deep snow (Meagher 1973), whereas cattle need to be subsidized under such conditions.
When confronted with a large predator, bison will be better equipped to protect themselves than cattle. Bison also evolved a cantering gait which gives them the ability to run long distances; this may be a way to escape predators on the prairie (Geist 1996).
Bison break trees and yucca that are growing on the grassland. This has also been noticed in Yellowstone National Park, where trees entering grasslands were affected by the horning and thrashing of bison (Reynolds et al. 1982). Meager (1973) speculated that such behavior by bison may inhibit the spread of trees onto the prairie and thus help maintain grasslands. Elk do this during the rut, but both sexes of bison do it on the Wind River Ranch throughout the year. Although fire played a large role in keeping shrubs out of grasslands, bison probably also contributed.
The wallowing of bison creates depressions in the prairie. These depressions can hold water, at least seasonally, and that benefits amphibians, mesic vegetation, and wildlife in general (Knapp et al. 1999; Truett et al. 2001). The localized wallows contribute to different patches of habitat across a landscape, thus promoting species diversity (Truett et al. 2001).
We have not had problems with bison breaking fences, and we use standard four or five wire fences that are 42 inches high. But, bison do handle much differently than cattle. You need patience to move them. On the positive side, you do not need a system of fenced paddocks for bison, nor do you have to rotate them through different pastures. Bison move themselves. Instead of rotational grazing, you can simply remove internal fences and let bison move themselves. Indeed, bison grazing and moving patterns contribute to habitat heterogeneity, and they produce a diversity of grass heights and species (Truett et al. 2001).
Finally, bison meat is healthier than domestic meats, particularly for people with diabetes or high cholesterol. Bison meat is low in cholesterol because there is no marbling of fat (Inter-Tribal Buffalo Council). Bison, meat and otherwise, are important to restoring cultures for many tribes (Inter-Tribal Buffalo Council).
In addition, bison may improve grassland health over use by cattle, but for people to switch from raising cattle to bison there must be a market for the meat. Balancing a market for bison with objectives of improving grassland health will require a great deal of thought and investigation (if it is possible at all). Given the market economy and low profit margins, there will be pressure to further domesticate bison (Freese et al. 2007). At present about 96% of the 500,000 bison in North America are bred and managed for commodity production (Freese et al. 2007). This means the bison is functionally extinct in the wild (Freese et al. 2007). While still present taxonomically, the bison does not exist in density or distribution that is sufficient for the species to reclaim its role as a highly interactive species of the prairie (Soulé et al. 2005). Restoring such species to population levels where they can again assert their role in ecological and evolutionary function is a prime goal of conservation; such population levels are typically much higher than numbers needed to retain viable populations, particularly minimum viable numbers (Soulé et al. 2005). Tribal initiatives, facilitated by the Inter-Tribal Buffalo Council, may present one of the best opportunities to restore free-ranging bison to their former function.
The Wind River Ranch now has a colony of Gunnison’s prairie dogs, thanks to fund-raising and labor by People for Native Ecosystems. Paula Martin headed the project. People for Native Ecosystems brought 300 prairie dogs to the ranch in 2006 and 2007. Those animals had been scheduled for poisoning in Santa Fe. The Gunnison’s prairie dog has just been classified as a Candidate Species for protection under the Endangered Species Act. Bison and prairie dogs largely created the grasslands that we use today and for their efforts they were shot and poisoned.
Like bison, prairie dogs probably also prevent the advance of trees and shrubs onto the grasslands. Everett (2002) found that shrub cover was 7.5 times higher outside of prairie dog colonies than inside of colonies in Wyoming. Similarly, mesquite (Prosopis spp.) increased from 27% to 61 % of the cover in the first 23 years after prairie dogs were removed from an area of Texas (Weltzin et al. 1997), and List (1997) saw a 14% increase in mesquite in the first 8 years after a prairie dog colony was poisoned in Chihuahua.
A grassland inhabited by prairie dogs provides a greater mosaic of vegetation structure, an abundance of prey for predators, burrow systems, and altered ecological processes (increased nitrogen content, succulence, productivity of plants, and macroporosity/chemistry of soils) than uninhabited grasslands. Such changes enrich patterns of species diversity for prairie plants and animals (Coppock et al. 1983; Ingham and Detling 1984; Krueger 1986; Whicker and Detling 1988; Detling 1998; 2006).
For example, species like black-footed ferrets, mountain plovers, ferruginous hawks, and forbs profit from prairie dog activities. On the other hand, shrubby species like mesquite and vertebrates associated with tall vegetation are limited by prairie dogs. The matrix of ecological boundaries created by prairie dog colonies improves overall diversity of life across a landscape (Miller et al. 2000; Kotlier et al. 2006). In the jargon, that is called Beta diversity.
Alpha diversity is basically species richness, or the number of species within a given patch of habitat. If there is only one habitat type across a landscape, then alpha diversity is all you will have. But, species like prairie dogs, bison, elephants, or beavers are ecosystem engineers, and they create differing patches of habitat across the landscape. Habitat A will have a set of species for its alpha diversity, whereas habitat B will have a different set of species for its alpha diversity. Both habitats may have the same number of species, but the species are different. Beta diversity is the number of species contained across those different habitat types. It is thus a better measure of ecosystem health.
In a recent review of 206 vertebrate species seen on prairie dog colonies, 9 had quantitative data indicating dependence on prairie dogs (Kotlier et al. 1999). An additional 20 species had abundance data indicating opportunistic use of prairie dog colonies, and another 117 species had no abundance data on or off colonies, but their life history indicated that they could potentially benefit from prairie dog activities (Kotlier et al. 1999). The prairie dog thus fits the general classification of a keystone species (Miller et al. 1994; 2000; 2007; Kotlier et al. 1999; 2006; Soulé et al. 2005). They affect ecosystem structure, function, and composition in a way that is not wholly duplicated by any other species.
The keystone concept means prairie dogs must be protected for more than their own intrinsic value. While intrinsic value is important, so is the impact on other species and processes. Species that are highly interactive should be maintained in distribution and density that is sufficient for them to exercise their ecological role—not just remain taxonomically represented (Soulé et al. 2005). As one example, a colony of prairie dogs covering 1,000 hectares may hold 5,000 prairie dogs. That number likely would be enough to maintain a taxonomic representation of prairie dogs. But a prairie dog colony of 1,000 hectares would only hold about 20 black-footed ferrets, a number so small that the ferrets would not be able to survive genetic, demographic, or chance events. It is possible to protect a small number of prairie dogs without conserving sufficient prairie dog area to maintain a viable population of black-footed ferrets (Miller et al. 2000). That is the importance of considering ecosystem effects in conservation plans.
Our small prairie dog colony will provide research into the role of prairie dogs on grasslands, into grazing interactions among species (including levels of competition among grazers), and disease transmission (e.g. plague, and exotic disease from Asia) among and within species.
Historically, the Mora River flowed across the center of a meadow in the canyon. At some point in history, the part of the river that flowed through that meadow was moved over against the canyon wall and diked. The river was also straightened. This produced a field for farming that was not bisected by the river. It also caused the channel to deepen, lowered the water table, increased erosion, removed the river from its natural floodplain, and increased the potential for flooding down-river.
Constructed Wetland Arial View of Wetland
The old river channel still carries water below-ground. Bill Zeedyk (Zeedyk Ecological Consulting) and Craig Sponholtz (Drylands Solutions) designed a way to restore that former wetland by building four small ponds. The ponds and associated soils cover about 35 acres in total. Two of the ponds are open for waterfowl and are surrounded by grasses and coyote and peachleaf willow. The other two are near a cottonwood bosque, and we are planting coyote willow, peachleaf willow, black willow, and cottonwoods around those ponds. The different levels of canopy should attract the endangered Southwestern willow flycatcher to nest. We have recorded willow flycatchers on the ranch, including some during summer, but we have not positively identified a nest.
The wetland, along with associated plants, will also benefit neotropical migrant birds, waterfowl, turkeys, ungulates, raptors, and carnivores. The cost of the ponds were covered by the Landowners Incentive Program grant.
The ponds offer research opportunities to monitor changes in flora and fauna that come with the wetland restoration.
Approximately 75 years ago, a one kilometer segment of the Mora River on the Wind River Ranch was straightened for agriculture. As a result, the river has deepened its channel and no longer has access to its traditional flood plain (an incised channel). The water table has lowered, and erosion has increased.
Stable rivers that meander across valley floors have functional floodplains, or areas that occur naturally along the stream where the river deposits water during flood events. Floodplains are thus pressure relief valves for a river (Zeedyk and Clothier 2009). When flood waters spread across the vegetated floodplain, it spreads the energy of the river and creates resistance. By dissipating energy and slowing flows, floodplains reduce erosion of the bank and bed of a flooding river. Flooding deposits rich sediments onto the floodplain, recharges water tables, creates diverse habitats, and sustains communities of plants and animals (Zeedyk and Clothier 2009). A river confined to its channel is a river that is deprived of its ecological function.
We have restored meander to the segment of the Mora River that was straightened about 75 years ago. Quivira Coalition, Dryland Solutions, and Zeedyk Ecological Consulting secured an EPA grant, and we secured grants from the U.S. Fish and Wildlife Service’s Partners for Fish and Wildlife and the Denver Zoo to restore that area of river. This was done by a technique called induced meandering, which is a method of transforming incised channels by guiding the river’s energy.
Induced meandering relies on geology, hydrology, biology, and ecology to understand and use the river’s processes and rules, stressing that the river’s force is to be respected, not coerced. Induced meandering tweaks the system to help water flows speed the natural process to create a meandering channel. Structures include vanes and baffles to deflect water into walls to help create a meander. Structures to maintain the river bed (prevent further incision) are one-rock dams, cobble run-downs, cross-vanes, and filter dams. Structures are made of natural materials such as boulders, cobble, posts, tree trunks, and living materials gathered from the area.
The first step is an assessment to view the present conditions and cause of the problem. If the problem isn’t addressed, it makes little sense to build structures. A Rosgen (2008) survey to determine the type of stream channel is next. This will reveal the slope of the river, the bank-full width (width at which the river should spill into the floodplain), maximum bank-full depth, sources of sediment, type of riverbed, meander length, distance from riffle to riffle and pool to pool, watershed area, and vegetation structure. An intact reference section of the river can serve as a model for restoration of an incised channel. If no segment of the river is intact, or no section of any of the surrounding rivers is intact, the straightened channel can be restored using mathematical formulas to model predicted results because river rules can be explained mathematically. The complete meander wavelength generally is equal to the bank-full width of the river multiplied by 12 to 15 times, depending on site conditions. A meander will form an S pattern, so a complete wavelength would be the distance from the top of the meander on one bank to the top of the next meander on that same side of the river. For more detail on the formulas that can be employed, and the circumstances under which the different formulas should be used, see Zeedyk and Clothier (2008). Induced meander techniques only work on incised channels with a slope of less than 4 degrees.
The structures that have been installed in the Mora River will reduce erosion and reverse the deepening of the channel. That will allow the Mora River access a floodplain, which should help raise the water table, making the surrounding grasslands more productive. Restoring moisture and plants to a degraded area slows air movement, provides shade, reduces evaporation, slows water flow, holds soil in place, and the ground litter from plants adds organic content. This structural change provides habitat for a host of vertebrates and invertebrates. Adding wetlands, as well as increasing vegetation cover, will improve habitat for the southwestern willow flycatcher, which is present on the ranch. Such wetlands are also a rich habitat for voles, an important prey item for many mammalian species and raptors.
River Before Restoration River After Restoration
Water Diverted to Place a Wetland in a New Floodplain
Despite Leopold’s half-century old advice on “intelligent tinkering” we have not kept “every cog and wheel.” Historical impacts over the last several hundred years have caused declines in species diversity. When “cogs or wheels” are lost, a system can fluctuate outside of the bounds to which it has adapted. Once such a vortex has been entered, secondary extinctions begin. It can become exceedingly difficult to reverse the decline in biodiversity.
As a basic step, we first need to know “what species are here.” Then, understanding abundance, distribution, habitat choice, and ecological interactions of vertebrates and invertebrates can promote management decisions that benefit overall ecosystem health. Monitoring programs that build an ecological model of the landscape, and assess the trends in relation to biotic and abiotic changes, are essential to adaptive management; yet such programs are not always a standard part of management activities (Noss and Cooperrider 1994; Lancia et al. 1996; Noss et al. 1996). Indeed, a conservation and management plan requires standardized ecological monitoring so that actions can be adjusted according to new information (Noss et al. 1996). The term monitoring implies data collection over multiple years. Taking long-term estimations of population composition before, during, and after biotic and abiotic changes provides needed information to assess the impacts of such changes and furnish useful options for management decisions (Sinclair 1991).
The refuge needs a detailed survey of flora and fauna that are present today. In examining the list of Species of Greatest Conservation Need (SCGN) for riparian areas and for western Great Plains shortgrass prairie (Thompson 2006-2007; Appendix A), we have present on the refuge: peregrine falcon (Falco pereginus) bald eagle (Haliaeetus leucocephalus), northern harrier (Circus cyaneus), ferruginus hawk (Buteo regalis), golden eagle (Aguila chrysetos), long-billed curlew (Numenius americanus), Band-tailed pigeon (Columba fasciata), mourning dove (Zenaida macroura), Lewis’ woodpecker (Melanerpes lewis), loggerhead shrike (Lanius ludovicianus), piñon jay (Gymnorhinus cyanocephalus), bank swallow (Riparia riparia), yellow warbler (Dendroica petechia), tiger salamander (Ambystoma tigrinum), puma (Puma concolor), and mule deer (Odocoileus hemionus). The New Mexico Audubon Society has declared the ranch as an Important Bird Area. mammals.
We intend to continue surveys for mammals, birds, herps, and insects using standard censustechniques.
Broom snakeweed (Gutierrezia sarothrae) is a native plant of the gasslands. It is poisonous to cattle and sheep, and it can supress other plants in the immediate area. It has become overabundant locally, perhaps as a result of fire supression and overgrazing during drought years.
In an experiment, McDaniel et al. (1997) compared burning grasslans with broom snakeweed in spring and in summer. During spring, fires were cooler and moved faster; in addition, broom snakeweed was in the bud stage. Summer fires had higher temperatures. McDaniel et al. (1997) found that spring fires killed 8% of the crown and 65% of the srubs while summer fires killed 66% of e crown and 92% of the shrubs.
McDaniel et al. (1997) tried to burn on consecutive yearts, but conditions made that difficult. They concluded that ideal conditions needed to converge for fire to be effective on snakeweed. Given that snakeweed declines can increase density of grasses, Dr. Edward Martínez (New Mexico Highlands University) and the Wind River Ranch Foundation are comparing mowing methods to see if that can reduce snakeweed and increase grasses. We presently have four years of data on is experiment. We are mowing in the summer when the energy is in the plant and not still stored in the root.
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