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1
IS PATCH-BURN GRAZING DAMAGING
MISSOURI’S NATIVE PRAIRIE?
DON KURZ
November 2010
SUMMARY
The Missouri Department of Conservation (MDC) has recently embarked on a potentially
damaging prairie management technique, the success of which is measured by weight gain of
cattle, variation in vegetation structure, and use by grassland birds. This procedure, Patch-Burn
Grazing (PBG), applies burning in patches, which attracts grazing cattle that in turn creates
vegetation structure attractive to some grassland birds. The technique is said to have no lasting
impact on prairie vegetation composition. However, PBG was developed on Oklahoma
grasslands that previously had a century of cattle grazing, followed by treatments with broadleaf
herbicides. This prior treatment obfuscates interpretation of how PBG impacts high quality
prairies. The recent application of PBG on high quality prairies in Missouri has been poorly
studied and interpreted, but the research is being used to justify its ongoing application. This
report reviews those studies and the potential impacts on continued PBG application to high
quality prairies.
─ Niawathe Prairie Natural Area, Dade County, Missouri was one of the PBG study areas. This
was one of Missouri’s flagship public prairies known for its high natural quality.
─Niawathe Prairie and Taberville Prairie, two of the five prairies used in the PBG study, are
state designated natural areas that represent some of the best, and last, examples of the state’s
original natural landscape. These natural areas represent fragments of formerly widespread
grasslands, and may not recover from grazing impacts.
─ Of the 15 million acres of prairie that once covered approximately one-third of Missouri, less
than one percent (fewer than 90,000 acres) remains intact. These remnants are priceless
examples of an imperiled ecosystem and an example of the state's natural heritage. They must be
protected and not used in short-term experiments. Priorities are askew in comparison to MDC’s
Missouri Ozark Forest Ecosystem Project (MOFEP), a 100-year study on a thriving, expanding
forest. Missouri has 14 million acres of forest land, and ranks seventh out of the 20 northeastern
states in the amount of forested acreage.
2
─Livestock overgrazing is well known for its damaging effect on vegetation, causing declines of
plants sought after by cattle and an increase in unpalatable plants, including alien and invasive
species. No comparative data have been used to support stocking rates on the PBG treatments on
Missouri prairies.
─Livestock grazing can also increase soil erosion and cause adverse water quality impacts from
increased runoff from the animal’s urine and feces. Antibiotics administered to cattle are readily
absorbed by plants from the cattle’ manure. Whether this is causing damage to insect herbivores,
pollinators, and others in the prairie ecosystem is unknown.
─ The original PBG report provided little useful information on either bird or vegetation
responses to grazing. Its most important finding was an average 17.46 bird species occurring on
burn vs. 20.17 species on the burn + graze units. However, almost 80% of the birds occurring
only in the grazing units are not prairie birds
─ The study did not consider the size of the five prairies studied and how nest predation and
brood parasitism might have influenced the monitoring results, nor did it include demographic
information, such as nesting attempts and nesting success.
─ Cattle grazing impacts on plant abundance are greatly influenced by stocking rates and
duration, factors that were overlooked in the Missouri study.
─During the four-year monitoring program, there was no analysis of individual plant species
abundance between grazed and ungrazed treatments.
─ Given the short duration of the MDC study and the methods of analysis used, the results are
not all that clear. It is also unknown whether the conclusion that PBG does not significantly
impact the vegetative community would remain valid when compared to a longer term study.
Don Kurz has had over 30 years of experience inventorying prairies and recruiting, training and
supervising staff to monitor and evaluate prairies. He was Natural History Lands Specialist for the MDC,
responsible for a comprehensive county-by-county Natural Features Inventory to locate the best
remaining examples of our natural heritage, including a complete survey of the state’s prairies. He has
also examined and evaluated tallgrass prairies throughout the ecosystem’s 13-state range. He coordinated
acquisition of high quality natural areas, including prairies, for the state of Missouri, which involved
setting acquisition priorities, evaluating areas, preparing acquisition proposals and Conservation
Commission actions, and working with area managers to set management goals. This acquisition work
resulted in state-wide protection of 80 special sites totaling 17,020 acres, including acquisition of 25
prairies totaling 5,710 acres. He also served on the Missouri Natural Areas Committee and the Missouri
Ozark Forest Ecosystem Project's long-range task force.
─Don Kurz, Jefferson City, MO; [email protected]
3
INTRODUCTION
Yet the more we love this place as it is, the more we feel the pain of what it so recently was. The
wild prairie ecosystem is gone. And this tragedy is compounded by the realization that we don’t
even know exactly what it is that we have lost.
─ Candace Savage (2004)
At the time of European settlement, approximately 360 million acres of shortgrass, mixed-grass,
and tallgrass prairie spread across the mid-continent from Canada to Mexico, stretching from the
foot of the Rocky Mountains to the great deciduous forests of the East. Today, these native
grasslands have been plowed, paved, overgrazed, and drained into mere fragments of their
former selves.
One group of animals that has suffered greatly from this process is prairie birds. Three out of
four grassland bird species have declined in abundance over the last 30 years, and these birds
have exhibited the steepest population declines of any North American birds (Nickens 2010). In
an effort to benefit prairie birds, the Missouri Department of Conservation (MDC), initiated a
program known as Patch-Burn Grazing (PBG). Developed on the western edge of the tallgrass
prairie in the Flint Hills of Oklahoma, PBG applies burning in rotated patches, where grazing
creates variability in vegetation structure that provides improved habitat for grassland birds
(Jamison and Underwood 2008).
The basis for MDC’s PBG program comes from a four-year (2005 to 2008) study (Jamison and
Underwood 2008) conducted on five prairies owned by MDC and/or The Nature Conservancy
(TNC). This report questions the methodology and findings of that study.
4
Using overgrazed prairie as unreliable benchmarks
Resolved, that none of us know, or care to know, anything about grasses, native or otherwise,
outside the fact that for the present there are lots of them, the best on record, and we are after
getting the most out of them while they last.
─A resolution by a West Texas cattleman's organization in 1898 quoted in Paul Shepard's book
Nature and Madness.
Much of the early PBG research was conducted in Oklahoma (Fuhlendorf and Engle 2001,
2004), a state that has had a long history of prairies being grazed by cattle. Unfortunately, little
information about past grazing history and its effect on prairies appears in PBG studies. Daniel
Licht (1997) wrote, ―The factors responsible for the destruction of the grassland ecosystem have
been so multi-pronged and so interconnected that it is difficult to know where an examination of
them should start.‖ It is important to understand the past use of these study sites, so one can get a
better understanding of how to interpret and apply the results of PBG. For example:
Tallgrass Prairie Preserve, Oklahoma
In 1989, The Nature Conservancy purchased the 30,000-acre Barnard Ranch in the southern part
of the Flint Hills. This acquisition became the Tallgrass Prairie Preserve, the largest remaining
protected prairie. The vast prairie landscape is an incredible sight but, unfortunately, it is mostly
grass, with little forb diversity. The area, as has most of Oklahoma’s prairies, been subjected to
well over 100 years of moderate to intense grazing by cattle along with late spring burns. This
has resulted in a landscape where the number (richness) and abundance (population size of
species) of plants and animals typically found on ungrazed or high quality prairies are greatly
reduced. The resulting difference between the Tallgrass Prairie Preserve and a high quality
prairie in Missouri is obvious even to the amateur prairie enthusiast. In addition, the 30,000 acres
was aerial sprayed with a broadleaf herbicide prior to the rancher’s selling the property to TNC.
This information is not found in TNC’s brochures nor is it mentioned in published studies except
in Hamilton (2007): ―Aerial application of broadleaf herbicides on a 4- to 5-year rotation was
practiced since the 1950s until the ranch was purchased by the Conservancy, and is still a
common regional range management practice.‖ The chemicals triclopyr and 2,4-D were
commonly applied for woody brush control and broadleaf plants (forbs) (Nelson, 1978).
In 1993, I was asked to consult on a film for the National Geographic Society using TNC’s
Tallgrass Prairie Preserve for the film location. The producer and principal cinematographer,
Maryan Smith, was having trouble finding sites on the preserve to film showy aspects of the
prairie. There were plenty of grasses but the forbs were few and far between. With the assistance
of Tom Toney, MDC’s prairie biologist, we located suitable areas on some MDC prairies where
they could film. Later, I visited the film crew at the Tallgrass Prairie Preserve and was amazed at
how few forbs there were on the prairie. Another visit to the preserve this past July 2010 (17
years later), revealed little improvement in the diversity and abundance of the forbs. And, in
most areas of the vast prairie, the undesirable nonnative white sweet clover had become a
dominant forb.
5
The filming was a success and resulted in a National Geographic Explorer special called ―Fire
and Thunder.‖ It aired June 25, 1995, on the TBS Superstation. Had not some of Missouri’s high
quality prairies been available, the film wouldn’t have been able to showcase one of the most
outstanding features of the tallgrass prairie.
Konza Prairie, Kansas
The 8,600-acre Konza Prairie also has a grazing history. It was purchased by The Nature
Conservancy in 1977 and deeded to the Division of Biology, Kansas State University for
operation as a Biological Station and long-term ecological research site. Unlike the Tallgrass
Prairie Preserve, this preserve is now grazed by bison. However, the preserve was once part of
the 10,000-acre Dewey Ranch, which was acquired and operated by C.P. Dewey and his son,
Chauncey, from 1872 to 1926. The prairie has had a long history of cattle grazing including
Dewey annually buying cattle in Texas and shipping them by rail to stockyards on the east side
of Manhattan, Kansas. From there they were driven and kept at the ranch, as many as 2,000 at a
time (Konza Prairie Biological Station 2010).
The histories of both of these research prairies illustrate an important factor. Over 100 years of
moderate to heavy grazing by confined cattle sets an unnatural baseline that is not taken into
account when conducting present research on the flora and fauna of the site. Critical questions
are: What was the composition of such prairies before extensive cattle grazing, how do they
compare with ungrazed prairies, and how do their current conditions affect the results of grazing
research? For example, might positive responses of species (to grazing) that have been selected
by a century of grazing give the impression that grazing has a positive effect on prairie? The
same question applies to species that have been selected by frequent aerial spraying with
broadleaf herbicides.
Grazing and the natural quality of prairies
Survey work for grading prairie vegetation was pioneered by Dr. Robert F. Betz and first applied
statewide by the Illinois Natural Areas Inventory, and subsequently in Indiana and in Missouri.
Quality grades are based on vegetation composition linked with evidence of human disturbance.
Grade A represents undisturbed late successional vegetation, grade B represents moderately
disturbed mid-successional, grade C heavily disturbed early successional, and grade D very
heavily disturbed early successional (White 1978). These grades also correspond to levels of
species richness, with grade A prairies having greatest small scale species richness, and fewer
alien plants (Bowles and Jones 2006). Multiple human factors may cause these changes,
including soil disturbance, herbicide application, and fire protection. A primary disturbance
affecting grades is the intensity and duration of past grazing by cattle, which is well known for
its effect on "increaser" and "decreaser" plant species (e.g., Drew 1947). Research in western
tallgrass prairie with a grazing history, such as Konza, suggests that grazing may select for
increasing species richness (Knapp et al. 1998). In reference to the natural quality of the
Tallgrass Prairie Preserve and Konza Prairie, both are grade C (Kurz, pers. obs.).
6
Ungrazed prairies as benchmarks
Table 1. Size in acres of Missouri prairies being impacted by patch-burn grazing.
Site Name Owner Grazing Unit Control Unit
Bethel Prairie Conservation Area
Hi Lonesome Prairie Conservation Area
Niawathe Prairie Natural Area
Taberville Prairie Natural Area
Wah’Kon-Tah Prairie
MDC
MDC
MDC/TNC
MDC
MDC/TNC
154
262
173
242
243
104
213
145
218
240
Niawathe Prairie Natural Area, Missouri:
“Niawathe” means “the life giver” in the Osage Indian language, and in spring and early
summer Missouri’s Niawathe Prairie gives life to fields of pale purple coneflowers.
─John Madson (1993)
Niawathe Prairie Natural Area, Dade County, Missouri was one of the PBG study areas (See
Table 1). This is (was) one of Missouri’s flagship public prairies with 160 acres owned by MDC
and 160 acres by TNC. The prairie has a recent history of hay mowing and burning. The north 80
acres had a natural quality rating of grade A, the central 160 acres had zones of grade A and B,
and the south 80 acres was grade C. The latter unit has lower forb richness and abundance
suggesting that a broadleaf herbicide was used by a previous owner (Toney 2010). A review of
MDC’s Missouri Natural Features Inventory for the five prairies in the PBG study would have
found a range of natural quality ratings from grades A to C-. These differences in composition
and quality might confound interpretation of PBG effects.
Niawathe Prairie was widely known by prairie enthusiasts and professional researchers as an
exceptional prairie with areas of high natural quality and scenic appeal (Fig. 1, 2, 3, and 4). This
prairie was one of only a few MDC prairies that were selected for ―Prairie Days,‖ a special
annual event that was conducted for a decade or so to celebrate the beauty and diversity of the
prairie ecosystem. The public was invited for a day on the prairie with interpretive walks, living
history reenactments, and featured specialists with live prairie animals. Niawathe Prairie was a
special place that generated amazement and inspiration in those that appreciate high quality
prairies.
7
Fig. 1. Niawathe Prairie pre-PBG with coneflowers. (Photo taken June 1995)
Fig. 2. Niawathe Prairie showing PBG results with a solitary coneflower and an
abundance of ashy sunflowers, an increaser. (Photo taken June 7, 2010)
8
Fig. 3. Niawathe Prairie pre-PBG with tall blazing stars. (Photo taken July 1995)
Fig. 4. Niawathe Prairie PBG results showing no tall blazing stars (Photo taken July 10, 2010)
9
State Designated Natural Areas:
Niawathe Prairie and Taberville Prairie are two of the five prairies used in the PBG study. Both
are state designated natural areas. Natural areas represent some of the best, and last, examples of
the state’s original natural landscape, each offering an exemplary model of Missouri’s
outstanding biological and geological features. They are special places where native vegetation
remains in a relatively undisturbed condition with many to most of their biological constituents
and processes intact.
Natural areas are repositories of genetic diversity contained in plants and animals that have high
scientific value, and may one day reveal important medical or economic values as well. Natural
areas provide important ―living laboratories‖ and ―outdoor classrooms‖ for scientists and
teachers to use for research and teaching. They provide ecological benchmarks and seed sources
for restoration projects of already degraded land. Many natural areas provide essential habitat for
species of conservation concern. Natural areas are important sites that protect remnants of the
state's natural heritage for aesthetic, scientific, and even economic reasons (Missouri Department
of Conservation 2010b).
The future of Niawathe Prairie Natural Area is uncertain (Fig. 5). The north end, which is (was)
grade A, will be subjected to its third year (2011) of grazing following the PBG study (Hedges
2010, Leahy 2010). This strategy does not follow the recommended management cycle for PBG
sites. There is a concern that too much responsibility is being given to area managers that may
not be aware or understand what a healthy functioning prairie ecosystem looks like. This lack of
understanding is reinforced by MDC’s maintaining a low priority interest in doing research on
what the ideal rest period is for grazing-sensitive prairie plant species, or the impact on possibly
sensitive insect species (i.e., prairie mole cricket), or possibly sensitive stream biota, or
acceptable soil bulk density values. These data gaps in using PBG are given low priority for
future study (Leahy and Underwood 2010). It also apparently gives an inappropriate message to
prairie visitors and adjacent landowners that repeated grazing is an acceptable conservation
management strategy. Niawathe Prairie, like all fragmented prairies, can be compared to an
island but instead of being surrounded by an ocean, the prairie is bordered by a sea of crop fields,
roads, and pastures. Some plants and animals may have been stressed beyond recovery. A four-
year study may not provide enough information to assess such damage.
10
Fig. 5. The future of Niawathe Prairie Natural Area is uncertain. (Photo taken June 7, 2010)
Endangered Prairie Ecosystem:
Every American has the right as part of his cultural heritage to stand in grass as high as his
head in order to feel some small measure of history coursing his veins and personally establish
an aesthetic bond with the past.
─William H. Elder (1961) Needs and Problems of Grassland Preservation
Of the 15 million acres of prairie that once covered approximately one-third of Missouri, a 1999
estimate stated that fewer than 90,000 acres or less than 0.6 of one percent, remains today (Kurz
2003). Compare that to the state’s more than 14 million acres of forest land, which ranks seventh
out of the 20 northeastern states in the amount of forested acreage (Missouri Department of
Conservation 2010a). Priorities are askew when comparing a four-year PBG study on prairie, an
imperiled ecosystem, against a 100-year study on a thriving, expanding forest. MDC’s Missouri
Ozark Forest Ecosystem Project (MOFEP), is one of the most comprehensive ecological
investigations of forest response to timber harvest ever undertaken in upland oak ecosystems.
Unlike the PBG study, great attention has been given to the design and duration of the MOFEP
experiment and to coordination of the numerous associated research studies. In all, scientists are
currently conducting 12 far-reaching studies on MOFEP sites, and new studies will be added
throughout the life of the 100-year project. Some of the research involves examining vegetation
dynamics, downed wood, fungi, birds, small mammals, herpetofauna, invertebrates, and genetics.
Soil, geolandforms, ecological land types, and climate at the sites are also studied (Missouri
Department of Conservation 2007).
11
Such a detailed and long-ranged study has not been initiated on any of North America’s prairies
with the exception of ongoing scientific research on western tallgrass prairie at Konza Prairie.
Konza Prairie is a transitional Flint Hills type of prairie that has a history of heavy grazing by
cattle. A critical question is whether the controversial PBG application, based on short-ranged
and incomplete research, is making major changes to the composition and natural integrity of
many of the best remaining prairies across the prairie region.
PRAIRIE GRAZING
Many of the prairie’s flowers (“forbs” to the botanist) are “decreasers” that cannot tolerate
abuse by plow, cow, and mower. They tend to fade and fail in the course of agribusiness. Rugged
and successful as they are in climax prairie, they may never survive intense land-use
pressures─such as legumes that are avidly sought by livestock. Those plants have withstood
transient bison, but cannot live under the continuous trampling and overgrazing of most modern
pastures. ─John Madson (1993) Tallgrass Prairie
Fig. 6 Niawathe Prairie Natural Area showing impact from PBG. There is little vegetation
structure on this 80-acre TNC tract. (Photo taken July 16, 2009).
12
Bison vs. Cattle:
Native grazers historically inhabiting tallgrass prairie included bison, elk, white-tailed deer, mule
deer, and many small vertebrates and invertebrates. The extent to which herbivores, especially
bison, grazed tallgrass prairie is unclear (Steinauer and Collins 1996). The greatest numbers of
bison historically occurred in the mixed grass prairie region (McDonald 1981), and grazing
frequency and intensity were probably greatest in the western portions of the tallgrass prairies
close to the mixed grass region. Some suggest that bison were scarce in the Midwest later in the
summer because of the higher precipitation rates (more than 40 inches per year). Rain is known
to leach nutrients out of the grasses (Whitehead 2000, Schroeder 2010). Grazing in the Great
Plains offered more nutritious grasses due to lower precipitation rates (<20 inches per year)
(Gilmore 2009). One possible scenario for bison grazing in tallgrass prairie is many small
random herds in the dormant and early growing season with the majority migrating to mixed and
short-grass areas as the growing season progressed (Steinauer and Collins 1996). The frequency,
timing, and intensity of grazing by other herbivores in tallgrass prairie are also poorly known.
Bison are primarily graminoid feeders and consume higher proportions of the dominant grasses
than would be predicted based on grass availability in the landscape (Peden et al. 1974, Van
Vuren and Bray 1983, Steuter et al. 1995). Bison tend to avoid forbs and woody species, which
usually constitute less than 10% of their diet. Thus, within a bison grazing area, forbs are often
conspicuously left ungrazed and are surrounded by grazed grasses (Fahnestock and Knapp 1993,
Damhourehey and Hartnett 1997, Plumb and Dodd 1994, Steuter and Hidinger 1999). By grazing
predominantly on grasses and avoiding forbs, bison can increase plant species diversity by
suppressing the dominant grasses and releasing limited resources to a diverse array of forbs
(Steuter and Hidinger 1999).
Bison digest roughage better than cattle do and can subsist on forage of lower protein content,
for example (Truett et al. 2001). Bison, due to their social structure, also spend less time grazing
than cattle and more time in nonfeeding activities (Plumb and Dodd 1993). It is normal for bison
to graze, trample, and wallow at different intensities across landscapes. This creates a mosaic of
vegetative types and elevates plant species diversity. The nature of this mosaic may be altered by
availability of water, topography, previous grazing patterns, and fire (Truett et al. 2001).
Frank Mayer and Charles Roth (1996) described these social units in The Buffalo Harvest, a PBS
documentary. ―Do you remember reading about buffalo herds millions strong, moving in a solid
mass, and stopping trains and wagons? . . . . Of course the herd, this vast mass of animals, would
be under the leadership of a grand old buffalo bull, who would trot serenely at its head, issuing
orders and demanding instant and complete obedience.‖ But as they point out, these are
misconceptions. ―Most of the herds would run from 3 to 60 animals, with an average of around
15. In these small herds the buffalo traveled and fed, scattered over the plains, but each one
separate and apart from the other herds. Whenever they stampeded they did come together and
charged as one vast, solid herd. But when the fright passed they’d separate into their peculiar
small herd formation . . . . (whose) leader wasn’t a bull at all . . . . It was a cow, a sagacious old
cow who by the power of her intellect had made herself a leader. Buffalo society, you see, was a
matriarchy, and the cow was queen.‖
13
Cattle:
Livestock can be used as a management tool, like an AK-47 assault rifle can be used as a
hunting tool. Perhaps theoretically possible, but only with very careful control of the tool. With
either the cow or the assault rifle on fully automatic, bad things happen. At least the gun cannot
walk around and do what a gun does by itself.
─Andy Kerr (2010)
The MDC stocking rate on its public prairies is considered on the low end of the moderate range
(Leahy and Underwood 2010). This sounds relatively safe enough but there are no comparative
data to support light, medium, or heavy stocking rates on Missouri prairies. After reviewing the
before and after photos in this report, it seems appropriate to suggest that more study needs to be
conducted to determine what actually is a preferred stocking rate that meets MDC’s objectives
for prairie bird habitat and still safely accommodates the flora and the rest of the fauna that
constitutes a majority of the prairie ecosystem. One needs to take into consideration that plants
and microhabitats preferred by livestock receive excessive use even with light stocking rates
(Holechek et al. 2000). The most common practices that produce overgrazing are: (a) excessive
animal density on the land, (b) lack of rotation or longer residence time of grazers on a sub-plot
of the landscape unit, and (c) grazing at inappropriate times relative to the flora productivity
cycle (Hogan et al. 2009). Item (b) is claimed by PBG to buffer against this but burn patches may
be too small (or not enough of an attractant) to contain cattle, as they grazed only 64% of the
time in burn units in the MDC study (Jamison and Underwood 2008). In The Vegetation of
Wisconsin, John Curtis (1959) described the behavior of cattle when first put into tallgrass
prairie. Cattle seek out certain forbs ―like hidden candy at a child’s birthday party.‖
It is obvious that without proper land management practices the prairie ecosystem can be
damaged, as well as its biodiversity. Many species of plants and animals live in the tallgrass
prairie, so a disruption in their ecosystem can cause a decrease in the species’ density and
richness. With the loss of high quality prairie, many species especially of animals are at a greater
risk for predation and have a smaller food supply.
Cattle Country:
Missouri ranks second in the nation, second only to Texas, in total numbers of beef cows in
production, with over 2 million cows on 68,000 farms (University of Missouri 2010). To those
that are pro-conservation and concerned about the environment, that is not a bragging right. One
only needs to take a flight just about anywhere over Missouri and the extensive destruction and
conversion of natural habitat for grazing livestock becomes obvious. If demand for meat, poultry,
eggs, and dairy keeps pace with projections, by 2050 the environmental consequences of
livestock production could be responsible for 70 percent of the total greenhouse gas emissions
for the planet (Pelletier and Tyedmers 2010). Similarly, Pelletier and Tyedmers determined that
future livestock demand would consume 88% of all of the biomass that humans can safely
harvest from the Earth.
A recent report by the Food and Agriculture Organization of the United Nations (2006) calls
cattle the greatest threat to climate, forests, and wildlife. Cattle are ―responsible for 18% of
14
greenhouse gases, more than cars, planes and all other forms of transport put together.‖ This
includes the fuel burned making fertilizer, to produce the meat and transport it, as well as the
obvious cow flatulence and manure production of methane, 20 times more effective as a global
warmer than carbon dioxide (Alter 2006). Methane has gone up by 150% since the pre-industrial
period. Carbon dioxide has gone up about 30 percent. Methane is much more effective than
carbon dioxide at trapping heat in the atmosphere. The heating effects of methane emissions are
more than 60% greater than that of carbon dioxide (Harris 2010).
Globally, ruminant livestock produce about 80 million metric tons of methane annually,
accounting for about 28% of global methane emissions from human-related activities. An adult
cow may be a very small source by itself, emitting only 176-240 lbs of methane, but with 100
million cattle in the U.S. and 1.2 billion large ruminants in the world, ruminants are one of the
largest methane sources. In the U.S., cattle emit about 5.5 million metric tons of methane per
year into the atmosphere, accounting for 20% of U.S. methane emissions (Environmental
Protection Agency 2010).
Red meat consumption comes with a price; it produces 3.4 times as much greenhouse gas,
produces 17.5 times as much common water pollution, produces 4.5 times as much toxic water
pollution, and uses 4.9 times as much water and 20 times as much land as is needed to produce a
nutritionally equivalent amount of grain (Browner and Leon 1999).
Water consumption is also an important concern. To produce a single pound of meat takes an
average of 2,500 gallons of water—as much as a typical family uses for all its combined
household purposes in a month (Robbins 1998).
Livestock grazing can also increase soil erosion and cause adverse water quality impacts from
increased runoff. The animal’s urine and feces can enter ponded areas or be carried downstream
where they can affect aquatic life. There are possible negative effects of cattle on reproductive
success and post-metamorphic abundance of amphibians (Schmutzer et al. 2008, Murphy et al.
2003, Burton et al. 2009). Elevated ammonia, nitrite and nitrate from cattle have been shown to
decrease survival of amphibian embryos and larvae, negatively affect larval body size and
increase malformation rates (Jofre and Karasov 1999). Also, researchers have found that fish can
exhibit significant effects from cattle runoff pollution, e.g., females begin to exhibit male
characteristics, and vice versa, in areas of high hormone concentrations (Center for Food Safety
2010).
Antibiotics administered to cattle may also affect the health of prairie organisms. Today, close to
70% of the total antibiotics and related drugs produced in the United States are fed to cattle, pigs
and poultry (Union of Concerned Scientists 2010). Although this practice sustains a growing
demand for meat, it also generates public health fears associated with the expanding presence of
antibiotics in the food chain. Plants have been found to readily absorb antibiotics from cattle
manure. Minnesota researchers planted corn, green onions, and cabbages in manure-treated soil
in 2005 to evaluate the environmental impacts of feeding antibiotics to livestock. Six weeks later,
the crops were analyzed and found to absorb chlortetracycline, a drug widely used to treat
diseases in livestock. In another study in 2007, corn, lettuce, and potatoes were planted in soil
treated with liquid hog manure. They, too, accumulated concentrations of an antibiotic, named
Sulfamethazine, also commonly used in livestock. Plants that become laced with drugs meant to
15
treat infections can promote resistant strains of bacteria in the environment (Cimitile 2009).
Whether this is causing damage to insect herbivores, pollinators, and others in the prairie
ecosystem, is uncertain but is not a matter of concern given the current PBG priorities.
PRAIRIE BIRDS
The tender plants, the sweet flowers, the fragrant fruits, the busy insects, all the swarming lives
which had been native here for untold centuries were utterly destroyed…[The prairie] had
vanished as if it had all been dreamed…The pigeons, the plover, the chickens, the vultures, the
cranes, the wolves—all gone—all gone!
─Hamlin Garland (1899) Boy Life on the Prairie
Rohrbaugh et al. (1999) wrote: ―It is socially and financially impossible today to try and recreate
what an ocean of prairie must have looked like so it is very important now to work towards
management that will be as close as possible to what once was. Although there is no way to
determine accurately how natural grazing and fire regimes affected grassland birds in past
centuries, we do assume that grazing and fire shaped the prairie into a mosaic of habitats that
probably differed spatially and temporally in age, structure, and flora and faunal compositions.
This mosaic presumably created suitable habitat for populations of wintering and breeding birds
with diverse habitat requirements.‖
And, an MDC perspective offers this press release: ―Patch-burn grazing gives both ranchers and
conservationists an effective, low-cost way to fatten cattle and favor prairie birds.‖ (Low 2008)
Instead of a more holistic approach to prairie ecosystem management, PBG narrows its focus to
providing an environment that is best suited for cattle and some prairie birds. However,
information and relevance of the benefits for the latter are not that clear. For example, Davit and
Alleger (2008) wrote in a review of the MDC work that ―Overall bird species diversity was
greater in grazed areas than in ungrazed areas, with 32 species of birds observed each year of the
PBG study in grazed areas versus 28 or 30 observed in ungrazed areas.‖ The difference between
28 or 30 is not clear, but if 30 bird species were using ungrazed prairies versus 32 species on
PBG prairies that does not appear to be statistically significant. Because numbers are that similar,
a subsequent year may see the numbers reversed or even matched. Of the 32 species observed in
the four-year PBG study, seven are defined as obligate grassland species (i.e. able to survive only
in a grassland).
The original PBG report by Jamison and Underwood (2008) says that the bird species richness
differed significantly between treatments, with an average 17.46 species occurring on burn vs
20.17 species on the burn + graze units. However, these values differ only by 2.17 bird species.
Further, almost 80% of the birds occurring only in the grazing units are not prairie birds, so the
16
small differences between the burn and burn + graze units could be due to variation in this group.
The non-grassland birds are: eastern bluebird, wood thrush, American robin, black-capped
chickadee, tufted titmouse, downy woodpecker, cedar waxwing, Baltimore oriole, Carolina wren,
pewee, and orchard oriole, which suggests that there must have been woody vegetation in or
close to the sampling areas. The herons must indicate that there was standing water or a stream
nearby.
Exact frequencies are not given for the obligate prairie birds upland sandpiper and greater
prairie-chicken, only that they ―occurred frequently‖ in graze units and less than three times in
burn units. As a result, it is difficult to understand differences in abundance. The obligate
grassland species for which specific abundance data are given are the dickcissel, grasshopper
sparrow, Henslow’s sparrow, and eastern meadowlark. Two of these, the dickcissel and
Henslow’s sparrow, actually prefer the burn treatments over grazing, one or two years after fire.
Grassland bird species are also not totally restricted to prairies however. MDC’s informative
management guides for maintaining grasslands (Tall Fescue and Missouri Wildlife; Managing
CRP Grasslands for Bobwhite Quail) include stands of tall fescue, orchard grass, and timothy, as
well as prairie. So these obligate prairie birds are known to occur on various grasslands and not
strictly prairie. It is probably not an acquired adaptation to new habitat, but that the other
grasslands represent the same structure as prairie vegetation preferred by the birds. Of course,
prairie birds have had to adapt to non-native grasslands because of the great reduction of native
prairie and increase in agricultural land. It is well understood that many of these species are on
the decline because of the loss of ideal habitat. But prairie ecosystems are being compromised by
emphasizing a few birds without adequately understanding the impact that PBG is having on
over a thousand other prairie species.
Missouri’s grassland obligate birds are: greater prairie-chicken, Henslow’s sparrow, dickcissel,
bobolink, grasshopper sparrow, eastern meadowlark and upland sandpiper (Fitzgerald et al.
2000, Fitzgerald and Pashley 2000). Of these seven birds, only the greater prairie-chicken and
the upland sandpiper have precocial young that require bare ground immediately after hatching,
with overhead cover 10-15 inches tall (Leahy and Underwood 2010). The other species raise
their young for an extended period in the nest until they fledge, and require vegetative structure
for nesting cover. However, they differ in their requirements, with dickcissels and Henslow’s
sparrows preferring habitats two to three years after a burn. The young do not need open, bare
ground because they are confined to their nests until they take flight. Two other species are
classified as grassland obligate birds, the northern harrier and short-eared owl but they
overwinter in the grasslands and are not summer residents.
Many variables affect nesting success for grassland birds including vegetation height, density or
cover, and variability in structure, or heterogeneity. Fire, grazing, and time since disturbances
affect these variables and affect how birds choose habitats. For example, in grazed prairies
Rohrbaugh et al. (1999) found that nesting success was lowered for eastern meadowlarks,
17
grasshopper sparrows, and dickcissels and that it was difficult to isolate the effects of grazing
from the effects of burning. He also found that 13.5% of eastern meadowlark nests failed
because of trampling by cattle. The effect of fire and/or grazing on grassland vegetation and the
breeding biology of birds has been the subject of several studies, including Wiens (1973),
Whitmore (1981), Johnson and Temple (1986, 1990), Zimmerman (1988, 1996), and Herkert
(1994). Specific management recommendations that may be drawn or inferred from these studies
are often interspecifically contradictory, with a particular burning or grazing regime benefiting
one species to the detriment of another.
Bird Density:
Leahy and Underwood (2010) state that ―PBG has definite positive impacts for true grassland
bird species in terms of increasing densities or diversity in units with this treatment.‖ However,
the report by Jamison and Underwood (2008) does not provide any bird density data, only counts
and richness. Density is usually expressed as the number of species or individual per unit area,
such as 10 dickcissels/acre. In the report, vegetative structure gets 17 figures, but no statistical
tests are applied to these data! Birds get 5 tables and 7 figures, with only a single statistical test
applied to overall differences in richness between treatments. (Plants, by the way, only get 1
table and 3 figures.)
Density also can be a misleading indicator of habitat quality if it does not reflect importance in
population maintenance (Van Horne 1983). A great amount of time and energy went into
creating and measuring vegetative structure for MDC’s PBG study as evidenced by Jamison and
Underwood’s final report (2008). Unfortunately, the PBG study did not include demographic
information, such as nesting attempts and nesting success, for obligate grassland birds and what
effects competition, predation and parasitism (e.g., from cowbirds) might have had in influencing
nesting success. As a result, there is actually no information on the effects of the PBG treatments
on populations of these species.
If vegetative structure is a measure of the importance of using PBG in grasslands for maintaining
obligate grassland birds, grassland quality should be defined in terms of survival and
reproduction, as well as the density of the species occupying that grassland. For example,
Fretwell (1969) reported ―no positive correlation between density and suitability‖ for breeding
field sparrows where suitability was measured in terms of breeding success; densities were
higher in an area where breeding success was lower. O’Connor (1981) summarized data for a
number of migrants and non-migrant bird species in Great Britain. The species showed a pattern
of filling only certain, presumably preferred, habitat when densities were low, but filled the less
preferred habitats when densities were high. Here, density would be a good measure of habitat
quality in years of low-overall density, but would be a misleading indicator in years of high-
overall density.
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Krebs (1971), Atwood (1980), and Carrick (1963) demonstrated that when breeding birds are
territorial and favorable habitat is limited, a surplus of adults of breeding age (floaters) may
accumulate in poor habitat where either no breeding takes place or where breeding attempts are
largely unsuccessful, resulting in a sink for the species. (A sink is low quality habitat where
excess individuals move to but fail to reproduce or increase population size.) Without
demographic information for prairie birds in grasslands, it may be difficult to accurately assess if
PBG is having definite positive impacts in terms of increasing densities or diversity in units with
this treatment. Further, studies at the species level indicate that remaining large grasslands may
not be sufficient to prevent declines of many grassland birds (With et al. 2008).
Fragmentation:
The change that had taken place in the interval, (1871-1883),was almost beyond belief. Instead
of an open prairie some six miles broad by ten in length, covered with its original characteristic
vegetation, there remained only 160 acres not under fence…The transformation was complete....
As a consequence, we searched in vain for the characteristic prairie birds…We left our beautiful
prairie with sad heart, disgusted with the change which civilization had wrought. The same is the
history of all the smaller prairies in many parts of the state; and it will probably not be many
years before a prairie in its primitive condition cannot be found within the limits of Illinois.
─Ridgway (1889) The ornithology of Illinois
The fragmentation of prairies that once made up tens of thousands of acres or more has had a
detrimental effect on both flora and fauna, especially prairie birds. However, the Missouri PBG
study did not consider the size of the five prairies studied and how nest predation and brood
parasitism (brown-headed cowbirds) might have influenced their monitoring results. Herkert et
al. (2003) measured rates of nest predation and brood parasitism for grasshopper sparrow,
Henslow’s sparrow, eastern meadowlark, and dickcissel in 39 prairie fragments ranging from 60
to 100,000 acres in size in five states in the mid-continental United States. Throughout the
region, nest-predation rates were significantly influenced by size of habitat fragments. Nest
predation was highest (78─84%) in small (less than 250 acres) fragments compared to 54─68%
in large (less than 2,500 acres) prairie fragments. The sizes of the grazing units used in MDC’s
PBG study (See Table 1, p. 6), would fit in the former category of highest vulnerability to
predation and brood parasitism.
Differences in nest-predation rates between large and small fragments suggest that fragmentation
of prairie habitats may be contributing to regional declines of grassland birds. Maintaining
grasslands for bird populations, therefore, may require protection and restoration of large prairie
areas.
Rates of brood parasitism by brown-headed cowbirds, however, are not consistently related to
fragment size but are significantly higher in regions with high cowbird abundance.
Unfortunately, the Missouri PBG study did not take into account the influence that cowbirds had
on the nesting success of prairie birds. Studies have shown that the presence of cattle greatly
attracts cowbirds (Shaffer et al. 2003). In a Kansas study, cowbirds were significantly more
abundant in moderately grazed, annually spring-burned tallgrass prairie than in ungrazed,
19
annually spring-burned CRP fields planted to native grasses (Klute 1994, Klute et al. 1997). To
aid in their reproductive success, cowbirds need perches on which to view bird activity and
potential nest sites in prairies. Livestock act as perches or are sought out for protective cover.
Cattle grazing also creates a short vegetation microhabitat favored for foraging by cowbirds. And
cattle flush up insects as they move along and graze (Goguen and Matthews 1999).
Methods for reducing cowbird parasitism include: (1) acquire and manage large, simple-shaped
tracts rather than small or irregular-shaped tracts to reduce amount of edge (Robinson et al. 1993,
Ortega 1998, Clotfelter et al. 1999, Davis and Sealy 2000); (2) remove potential perches such as
woody vegetation or unnecessary fences (Stauffer and Best 1980, Robinson et al. 1993, Davis
and Sealy 2000); (3) during peak breeding periods of cowbirds host species, remove cattle
(Goguen and Matthews 1999, and (4) eliminate the PBG program.
Another decline in grassland birds is attributed to predators. Predators on grassland bird nests
vary and include mice, snakes, ground squirrels, weasels, badgers, foxes, coyotes, skunks,
raccoons, deer, crows, and hawks (Herkert et al. 2003). Feral cats also play a significant role in
nest predation (Northern Prairie Wildlife Research Center 2010). Some of these nest predators
can be more common near edges in some landscapes (Dijak and Thompson 2000; Winter et al.
2000). Fragmentation of grassland habitats, especially native prairie, could be contributing to
regional declines of grassland birds as a result of increased nest-predation rates on small
fragments that make up most of Missouri’s prairies.
Even in large grassland remnants, current land-management practices may be exacerbating
grassland bird declines by degrading habitat. Habitat area is thus no guarantee of population
viability in landscapes managed predominantly for agricultural or livestock production (With et
al. 2008).
Greater Prairie-Chicken
Unfortunately, the plight of the greater prairie-chicken in Missouri is not new. Restoration efforts
began 50 years ago with the reintroduction of 25 birds at Swan Lake National Wildlife Refuge
followed by a release in Macon County. Both attempts failed (Robbins and Easterla 1991). More
recently MDC has allocated considerable time and money to create suitable habitat and life
sustaining strategies to halt the rapid decline of the birds. PBG represents the most recent
attempt. Although noteworthy, the greater prairie-chicken reintroduction efforts have not gone
well. In 1989, Missouri had 3,000 greater prairie-chickens left. In 1999, the bird was listed as a
state endangered species. Recently, it was announced that fewer than 100 native greater prairie-
chickens occur in the state (Alleger 2010).
Ongoing problems that continue to defeat the establishment of a successful greater prairie-
chicken population in Missouri are: loss of permanent grassland habitat, degradation of existing
grassland habitat, improved agricultural practices that leave less waste grain in the field for
winter feeding, reduced genetic diversity, and increased predation.
20
Habitat size:
Greater prairie-chickens require large grassland landscapes with high amounts of open space
(Schroeder and Robb 1993). Opinions vary about the spatial scale needed to sustain a viable
population of birds. Hamerstrom et al. (1957) and Sample and Mossman (1997) indicate that
management of greater prairie-chicken core areas should consist of the following landscape
components:
A large area (10,000 to 50,000 acres) of open landscape not more than 20% wooded with
wooded tracts in small, scattered blocks and a limited number of linear treelines.
A core of permanent managed grassland at least 2,000 acres in size for every 10,000
acres of greater prairie-chickens range.
A minimum of 30% of the open lands in permanent grassland, including the core and
scattered blocks of grassland at least 80 acres or larger.
Scattered blocks of long-term grass cover (e.g. CRP, CREP and pasture) totaling an
additional 15-20% of the open landscape.
Adequate winter food supply.
On the low end of the scale, the Missouri Department of Conservation’s (2006) Greater Prairie-
Chicken recovery plan calls for:
A 10,000-acre landscape (wooded acreage not identified).
A core of 2,000 acres of grassland.
An additional 2,000 acres of surrounding grasslands within the 10,000-acre landscape.
Even if core areas were established somewhere in the range between 10,000 and 50,000 acres,
the ability to sustain a strong, viable population of greater prairie-chickens is uncertain.
Populations of many endangered species are unlikely to persist in the face of global climate
change and habitat loss unless they number around 5,000 mature individuals or more (Traill et al.
2010). A longstanding idea in species restoration programs is the 50/500 rule. This states that at
least 50 breeding adults are required to avoid the damaging effects of inbreeding, and 500
breeding adults to avoid extinctions due to the inability to evolve to cope with environmental
change. Populations smaller than about 5,000 have unacceptably high extinction rates (Traill et
al. 2010).
Predators:
As grasslands have been carved and isolated, patches of optimum hunting areas for ground-nest
predators have increased. These predators have no pressure from upper level carnivores, which
have been eliminated. They include: coyote, fox, bobcat, skunk, raccoon, and opossum. Some
have suggested that the reduction of fur trapping has been correlated with the increase of
mammalian predator numbers.
21
Great horned owls and red-tailed hawks also play a significant role in greater prairie-chicken
predation. Early work by Burger (1988) identified the role of hawk kills on booming grounds and
owl predation on nesting female birds. The removal of ―perch trees‖ is now a recommended
practice although not always carried out. (See Fig. 7).
Fig. 7. Niawathe Prairie Natural Area with a grove of ―perch trees‖ several of which are now 20
feet tall. Also note the edge effect along the right boundary. (Photo taken June 7, 2010)
Without management practices designed to address and reduce ground-nest predators, greater
prairie-chickens will continue to be at a disadvantage. As this newspaper article in the Jefferson
City News Tribune on September 2, 2008, reported: ―Coyotes and other predators have picked
off many of the 45 male prairie chickens that were relocated from Kansas to a prairie in western
Missouri this spring in hopes of boosting the state’s plummeting population.‖
The greater prairie-chicken restoration program has a number of things working against it that
ensure that small, isolated pockets of birds, over time, will continue to die out. Re-introductions
represent an investment in a false hope. With the present economy, direction of agribusiness, and
human interests there is nothing positive on the horizon for the greater prairie-chicken’s future in
Missouri. Perhaps the thousands of work hours and millions of dollars spent in this restoration
22
program, including PBG, could be redirected to ensure that 99% of the other prairie flora and
fauna have high quality prairies in which to live and for our future generations to appreciate and
enjoy.
OTHER PRAIRIE ANIMALS
Nowhere in the Great Plains does there exist a vestige of a naturally functioning grassland
ecosystem, or even a close simulacrum, because the prairie ecosystem has lost not only grass,
but also wildlife.
─Daniel S. Licht (1997) Ecology and Economics of the Great Plains
―Little data are available on the impacts of PBG to terrestrial invertebrates, small mammals, and
soils. However, the data that are available do not indicate there should be any undue concern for
the impacts of PBG to these resources. This is currently a low priority for future MDC research.‖
(Leahy and Underwood 2010)
In PBG, the emphasis on prairie birds overlooks other faunal and floral representation.
Management priorities need to address both generalists and specialists. That is why it is
important to conduct more detailed surveys and monitoring on prairies that are being selected to
be grazed by cattle. When considering generalists and specialists, management priorities need to
be established in favor of the latter (Swengel and Swengel 2001).
Unfortunately, there are a large number of animals to consider, many more than justifies the
priority of managing prairies for a few select birds. For example, all species of reptiles and
amphibians that exist on prairies are being overlooked by MDC’s PBG program. This also
applies to the PBG programs of other state and federal agencies, organizations, and academics.
23
Table 2. Amphibians and reptiles that inhabit Missouri’s prairies.
Salamanders
- Smallmouth Salamander
- *Eastern Tiger Salamander
Toads and Frogs
- Plains Spadefoot Toad
- Woodhouse’s Toad
- *Great Plains Narrowmouth Toad
- *Northern Crawfish Frog
- *Plains Leopard Frog
Turtles
- *Yellow Mud Turtle
- Ornate Box Turtle
Lizards
- *Great Plains Skink
- *Northern Prairie Skink
Snakes
- Prairie Ringneck Snake
- Great Plains Rat Snake
- Prairie Kingsnake
- Bull Snake
- Plains Garter Snake
- Blotched Water Snake
*Species of Conservation Concern (Missouri Species and Communities of Conservation
Concern, 2010)
From: Animal Management, Prairies. Missouri Department of Conservation Brochure
And, then there are the prairie mammals. Don Kaufman, professor of biology at Kansas State
University with 20 years of prairie research wrote: ―I realize that many people don’t think of
managing mice and other small mammals in the same way that they might agree with managing
deer or species like that. Even though the small mammals might not seem very important in one
way, their presence, in some natural sense, suggests that we’re trying to maintain the integrity of
our world, too.‖ He then goes on to say: ―The grazing of tallgrass prairies is another factor that
can greatly affect small mammal populations.‖ Much like the seasonal burning of the grasses,
heavy grazing by bison or cattle can lead to a decrease in the foliage upon which the small
mammal populations depend for survival (K-State Perspectives 2002). (Fig. 8)
24
Fig. 8. Sparse ground cover due to grazing over the 360-acre prairie provides little habitat for
small mammals and ground nesters. (Niawathe Prairie Natural Area, Photo taken May 2, 2010)
Table 3. Small mammals that inhabit prairies.
- Least Shrew
- Plains Pocket Gopher
- Prairie Vole
- Meadow Jumping Mouse
- Deer Mouse
- *Plains Harvest Mouse
- *Franklin’s Ground Squirrel
- *Thirteen-lined Ground Squirrel
- *Black-tailed Jack Rabbit
- *American Badger
- *Plains Spotted Skunk
*Species of Conservation Concern (Missouri Species and Communities of Conservation
Concern, 2010)
From: Schwartz, Charles. 1981. The Wild Mammals of Missouri. University of Missouri Press,
Columbia, Missouri. 356 pp.
25
PRAIRIE INSECTS
Much more work is needed in order to understand the effects that PBG has on hundreds of
species of prairie insects. A few species of butterflies have been selected in the past for study
with varying results, but a whole range of orders of insects are overlooked in the Missouri PBG
program. They include: true bugs, butterflies and moths, bees and wasps, ants, dragonflies and
damselflies, flies, leafhoppers, grasshoppers, and beetles. For example, one two-year study of a
tallgrass prairie in northeastern Oklahoma found 3,000 insect species (Risser et al. 1981) while in
a shortgrass prairie in Colorado, more than 1,600 insect species were found and this list is
incomplete (Kumar et al. 1976).
Prairies with a high species richness and abundance of insects are an important food source for
other animals, especially prairie birds and their young. Many of these insects are not very mobile
and do not range great distances, so if a prairie is abused from overgrazing and their food sources
are greatly reduced resulting in weakening or extirpating an insect population, it is very unlikely
that insect will be able to repopulate from another prairie miles away (Packard and Mutel 1997).
Using fire as a management tool can have positive effects on insect fauna. For example, fire has
been shown to increase insect abundance with both grasshoppers and beetles becoming more
abundant after a fire (Reinking 2006). Grazing as a management tool can also produce varied
effects depending upon management objectives. Fay (2003) found in grazed management units at
the Tallgrass Prairie Preserve (Oklahoma) and the Niobrara Valley Preserve (Nebraska) that
insect species richness and diversity were significantly higher in burned (Tallgrass) and
unburned (Niobrara) portions of bison units compared with their respective cattle units,
suggesting that habitat heterogeneity in terms of plant productivity, composition, and structure
were higher in bison versus cattle and ungrazed management units.
The following are some examples of how the intensity of grazing activity can greatly influence
the richness and abundance of prairie insects:
Prairie Mole Cricket: The largest mole cricket in North America and a species of conservation
concern (Missouri Natural Heritage Program 2010), prairie mole crickets are historically found
in only tallgrass prairies of four states: Missouri, Kansas, Oklahoma, and Arkansas. The species
was presumed extinct but in 1986, Dennis Figg and Paul Calvert conducted a systematic search
and found several populations of the prairie mole cricket on Missouri prairies (Figg and Calvert
1987).
Studies have shown that the male prairie mole cricket constructs an acoustical chamber that
amplifies its distinctive call in order to attract females. The chambers are arranged in a lek,
which is a gathering of males of certain animal species for competitive mating display. These
chambers are constructed on more recently burned sites (Howard and Hill 2007).
Since the PBG program focuses on spring burns to attract cattle to feed on the subsequent growth
of prairie vegetation, there could very well be a conflict with prairie mole crickets that depend on
trample-free chambers from April to June as an important element towards completion of their
reproductive cycle.
26
Prairie mole crickets are no longer present in the Flint Hills although this landform contains the
most tallgrass prairie remnant remaining today. Once historically known to occur there, these
insects do not tolerate cattle grazing (Figg and Calvert 1987) even though bison and elk once fed
there. Grazing may have once eliminated local populations of the prairie mole cricket, but the
disturbance was short-lived and the ungulates moved on (Figg and Calvert 1987). Private prairies
that were hayed and with no history of modern grazing are the reason these insects have not gone
extinct. Fire and haying are management tools that appear to have no adverse effects on prairie
mole cricket populations. Has this federally threatened species become extirpated from Niawathe
Prairie Natural Area due to the current grazing practices?
Bees: Bees are the most important pollinators of forbs which are an integral part to prairie
diversity. Andres and Rider (2007) examined the effects of prairie management on prairie bees in
western Minnesota. Their results showed that managing a prairie by burning and haying
produced the highest species richness (71 species on burned prairie and 53 species on hayed
prairie). Grazed and unmanaged prairie showed low species richness (27 and 26 species
respectively).
Regal Fritillary Butterfly: A species of conservation concern (Missouri Natural Heritage
Program 2010), the regal fritillary is declining across its range. During the PBG study, the regal
fritillary was twice as abundant on either the grazed or the grazed and burned units versus the
burn-only units (Leahy and Underwood 2010). However, according to Moranz et al. (2007),
who monitored the MDC PBG units, patches within burned and grazed units were almost
completely devoid of butterflies for much of the summer, whereas patches within burned
ungrazed units supported large populations of butterflies. This was also the situation in 2009 and
2010 at Niawathe Prairie, especially for the regal fritillary due to cattle being allowed to graze
the entire 360-acre prairie.
Regal fritillaries emerge from their overwintering larval (caterpillar) state in late May with the
males emerging a week before the females (Northern Prairie Wildlife Research Center 1995).
Their emergence in Missouri’s tallgrass prairies coincides with blooming of the pale purple
coneflower (Echinacea pallida), which flowers for about three weeks beginning in late May
through the middle of June. Unfortunately, the grazing intensity at Niawathe Prairie Natural Area
in 2009 and 2010 resulted in less than a dozen pale purple coneflowers (its main nectar source)
flowering where thousands had bloomed in the past. After mating, eggs are laid on suitable
larval food plants, which are primarily prairie violet (Viola pedatifida), birdsfoot violet (V.
pedata), and arrowleaf violet (V. sagittata) (Wisconsin Department of Natural Resources 1999).
The survival of these violets as host plants could be a problem because of the intensity of grazing
at Niawathe Prairie. Visits to Niawathe Prairie Natural Area in June of 2009 and 2010 found no
regal fritillaries occupying the prairie due to a lack of pale purple coneflowers.
More work needs to be done to better understand the influence that the PBG program is having
on prairies in regard to species richness and abundance of the thousand-plus prairie animal and
plant species that are being overlooked in favor of seven species of birds.
27
PRAIRIE PLANTS
The tallgrass prairie dazzles the eye with an unending array of blooming plants, and this
spectacle, with some seventeen new species coming into bloom each week, lasts from March until
October. The tallgrasses themselves, big bluestem, Indian grass, switchgrass, and cordgrass, to
name the common ones, are the most powerful, the most expansive, the most majestic of all the
prairie plants; they are the redwoods of the prairie.
─Patricia D. Duncan (1978) Tallgrass Prairie
Missouri prairies have an incredible diversity of native plants. The 186-acre Shelton L. Cook
Memorial Meadow, for example, has over 300 species of native plants (The Nature Conservancy
1991). Implementation of PBG on native high quality prairies such as Niawathe Prairie Natural
Area and Taberville Prairie Natural Area can have devastating effects on plant species, especially
when the outcome of such a practice focuses on vegetative structure over species richness and
floral abundance.
The conventional villain in the destruction of the grassland ecosystem is agriculture…[but it] is
not so much that agriculture has converted 43 percent of the prairie biome to cropland but that it
has fragmented virtually 100 percent of the entire prairie ecosystem.
─Daniel Licht (1997) Ecology and Economics of the Great Plains
As a result of fragmentation, isolated tallgrass prairie remnants may harbor greatly reduced
populations of both rare and common plant species. This process can lead to loss of genetic
diversity, reduced gene flow, and genetic drift (Karron 1989, Menges 1991, Heschel and Paige
1995, Stewart and Meingers 2010, Jennersten 1988). Inbreeding depression can then reduce
fitness by reducing plant size, seed numbers, and seed viability, and by increasing susceptibility
to environmental stress (Menges 1991, 1995). For plants with obligate outcrossing breeding
systems, fragmentation may also result in complete loss of reproduction if genetic diversity is
reduced to the point that plants are genetically uniform, such as single clones, or if they contain
only single self-incompatibility alleles.
Livestock grazing can directly impact plants through trampling and grazing, and indirectly by
compacting, exposing, and drying the soil. Such impacts most likely depend on grazing
frequency, length of grazing periods, and the stocking rate. These impacts are also affected by
management such as burning and mowing as well as environmental conditions such as
precipitation and depth to groundwater (Alexander 2006). Grazing may exacerbate fragmentation
effects on plant population viability by further reducing population sizes and health. Such factors
are being overlooked for the most part in PBG practices in Missouri, especially on high quality
prairies.
28
When it comes to studying plant responses to PBG, the emphasis is on vegetative structure for
bird habitat and not long-term survival of plant species, especially for prairie specialists.
Therefore, there is little information in the literature on the effects of grazing on plant species,
especially prairie specialists. The following are examples of some prairie specialists that may be
vulnerable to PBG:
Mead’s Milkweed (Asclepias meadii) ─Mead’s milkweed is an obligate outcrossing prairie
species that usually occurs in low population numbers (Tecic et al. 1998, Bowles et al. 1998). It
is a Missouri species of conservation concern and listed as endangered; it is classified as
threatened on the federal level (Missouri Natural Heritage Program 2010). Once found
throughout the middle and eastern part of the tallgrass prairie region, the species has dwindled to
extremely low numbers or has been extirpated from most states. In 1981, a survey at Niawathe
Prairie Natural Area yielded seven groups of plants for a total of 20 individuals. In 1983: 60
plants; 1984: 78 plants; 1985: 295 plants; and in 1986: 262 plants (Missouri Natural Heritage
Database). Although numbers at Niawathe Prairie Natural Area were encouraging in the past,
little is known about the impact PBG has on the survival of the species. I was told by the area
manager, in a somewhat humorous manner, that some of the plants were fenced inside cattle
exclosures but others were left to be grazed by cattle to see how they would hold up (Hedges
2009). Unfortunately, a loss of even a few flowering plants from grazing in this small population
could reduce the probability of successful outcrossing and seed set.
Western Prairie Fringed Orchid (Platanthera praeclara) ─ The western prairie fringed orchid
is a Missouri state endangered plant and federally threatened species (Missouri Natural Heritage
Program 2010). Alexander et al. (2010) monitored the effects of grazing on the survival of
orchids from flowering to mature seed capsule production, comparing plant height, flower
numbers, and seed capsule numbers from 2002 to 2004 in rotationally grazed prairies and non-
grazed sites. Mean orchid survival was 40% in grazed and 87% in non-grazed areas. Because this
perennial plant relies on carbohydrate reserves produced during the growing season to survive
winter dormancy and produce growth the next season, loss of above-ground photosynthetic parts
by grazing may disrupt the orchid life cycle, preventing flower production in subsequent seasons.
Without production of mature seeds, there is no contribution to the seed bank or recruitment of
orchids into the population (Alexander 2010, Bowles 1983).
Royal Catchfly (Silene regia) – In 1984 a survey at Niawathe Prairie Natural Area yielded
several hundred plants (Missouri Natural Heritage Database). This is another species of national
concern. Missouri is the epicenter for this species. Most other states throughout its former range
list royal catchfly as endangered or extirpated. Even in Missouri, its numbers are not secure. In
several locations in southwestern Missouri, these long-lived perennials are holding on in former
prairie that was converted to fescue pasture. Many have found protection along barbed wire
fences where they are less vulnerable, but these populations are in no way secure. There are few
prairies in the state where this species can still be found. Unfortunately, one of these once secure
populations occurs at Niawathe Prairie Natural Area. (Figs. 9, 10)
29
Fig. 9. Niawathe Prairie in southwest Missouri is among the showiest of Midwestern prairies
and one of the few having the rare royal catchfly. ─John Madson, 1993. (Photo taken July 2000)
Fig. 10. Winged sumac out-of-control after PBG study. Only one royal catchfly plant was
observed over two years and it did not flower. The color is from wicking using a herbicide. The
sumac dominated again the following year. (Photo taken July 10, 2009)
30
Oklahoma Grass Pink Orchid (Calopogon oklahomensis) – This recently described species is
not listed as a species of concern in Missouri. However, the status of this orchid may change in
the near future and warrant protection under the Endangered Species Act. A petition was
submitted by Douglas Goldman, who first described the orchid as a separate species (Greenwald
2010). The grass pink orchid (see Fig. 11) grows in upland prairies, where it requires frequent
burning and is under threat from forces like habitat destruction for urban and agriculture sprawl,
livestock grazing, and fire suppression. A population of this orchid occurs on the northwestern
part of Taberville Prairie Natural Area. Figure 12 illustrates the current status of this once high
quality prairie. The Oklahoma grass pink orchid is a prairie specialist that may be sensitive to
overgrazing and intense competition from prairie generalists. Unfortunately, once this population
is lost there will be no chance of recruitment from other fragmented prairies. If the reproductive
and growth cycle of this species is similar to the western prairie fringed orchid, it is vulnerable to
grazing.
Fig. 11. The showy Oklahoma Grass Pink Orchid, a species being considered for Federal
protection. (Photo taken June 1997)
31
More studies like the one conducted on the western prairie fringed orchid are needed in order to
fully understand the impact of what PBG is doing to these prairie specialists. However, the
deteriorating effects of repeated and concentrated grazing on obligate prairie species are obvious.
Effects of burning and grazing on prairie plants:
Prairies cannot survive without fire, but they may survive without grazing. Burning and grazing
have historically been the natural disturbance processes maintaining prairie ecosystems. When
prairies once occurred on a massive scale, plants and animals were able to recolonize following
local disturbances. Now that the prairie landscape has been fragmented, this process is not
possible. Much thought must be given to choosing which management tools to use and when to
deploy them. Burning has proven to be an extremely important method way to maintain prairie
vegetation because it increases cover and diversity of native species and reduces alien forb and
grass (predominately cool-season) species. For example, in an Iowa study, Brudvig et al. (2007)
found that burned units were dominated by native species and displayed the greatest cover of
warm-season grasses, native forbs, and shrubs as well as greater richness of these native species.
Conversely, grazed, and burned-and-grazed units had approximately 30% lower cover by native
species and, concomitantly, greater cover by exotic forbs and cool-season grasses compared with
burned units.
The PBG program promotes or tends to favor spring burns, a process that is known to stimulate
the growth of warm season grasses and suppress or diminish the growth of forbs (Knapp et al.
1998, 1999). Mid-to late spring fires (as practiced in Kansas and Oklahoma) can burn many
species of forbs that are beginning active growth, while leaving the still-dormant grasses
unharmed (Engle et al. 2000). This fire regime did not naturally occur routinely. Burning in the
summer or early fall to simulate the timing of lightning fire would favor plants that are
consistently infrequent or rare in many prairies (Howe 1994). So in order to achieve a more
natural condition that plants have evolved with, the timing of prairie burns should not be limited
to one particular season.
PBG also may select for unpalatable woody vegetation, especially winged sumac (Rhus
copallina) (Leahy and Underwood 2010). After the four-year MDC PBG program, major stands
of winged sumac developed and considerable time and cost was devoted to treating the shrubs
through herbicide application (rope wicking) and brush hogging. (Note ─ Since sumacs are
rhizomatous, there could be herbicide translocation to other plants). Winged sumac forms large
clones and can shade out other plants. Winged sumac is also allelopathic (the chemical influence
of one plant by another), which causes a toxic environment for other plants that leads to stunted
growth, stress, failed seed germination, and poor survival (Willis 2007). Refer to Figures 9 and
10 to see the likely effects of winged sumac on royal catchfly. In years 2009 and 2010, only one
stunted stem of royal catchfly was observed under an extensive winged sumac thicket and it did
not flower.
Although PBG originated in the Flint Hills of the Great Plains, its management approach is being
encouraged by multiple agencies and organizations in the Midwest. However, research is needed
to understand the consequences of this practice without destroying high quality prairies in the
process. Variability in grassland community response to burning and grazing may be a function
32
of differences in geographic region, climate, topography, and initial species composition, as well
as the timing and type of management (Bazzaz and Parrish 1982). Leach et al. (1999) suggested
that historically bison were not as abundant in the more eastern portion of the tallgrass prairie, as
they were on the western portion of the tallgrass prairie and in mid-and shortgrass prairies. As a
consequence they suggested that a positive relationship did not evolve between grazers and
eastern tallgrass prairies, leaving some plant species vulnerable to grazing. However, this issue
remains unresolved (Howe 1999; Henderson 1999).
Not nearly enough research has been done in Missouri to validate PBG as the best management
tool available to maintain the diversity and quality of its remaining prairies.
PRAIRIE VEGETATION STUDY
We must somehow take a wider view, look at the whole landscape, really see it, and describe
what’s going on there.
─Annie Dillard (1998) Pilgrim at Tinker Creek
Analysis of prairie vegetation sampled during the PBG study found no significant impact on the
vegetative community (Jamison and Underwood 2008; Leahy and Underwood 2010; Underwood
2010). However, given the short duration of the study, the methods of analysis used, and lack of
analysis of changes in species composition, the results are uninformative. It is also unknown
whether the conclusion that PBG does not significantly impact the vegetative community would
remain valid when compared to a longer period study.
The primary analysis used is the Floristic Quality Index (FQI). It claims to measure the floristic
quality of plant communities by assigning each native plant species a coefficient of
conservatism, a subjective rating that describes its affinity for remnant natural communities
(Ladd 1997, Taft et al. 2006). The mean coefficient of conservatism (mean C) is multiplied by
the square root of the number of native species sampled to obtain the Index value. This statistic
can be calculated by weighting species abundance. Jamison and Underwood (2008) based their
calculations on unweighted samples, which are not sensitive to compositional differences among
species. More seriously, the assigned coefficients are not unbiased nor independent measures, as
they are based on circular reasoning and tend to give higher values to rare plants. Plants thought
to indicate high natural quality are given high coefficients, which are then used to evaluate
quality. In a study of high quality Illinois prairies, it was found that these values could not
differentiate prairie quality nor different levels of disturbance to prairie and were not sensitive to
effects of fire management (Bowles and Jones 2006). Likewise, in Iowa, Brudvig et al. (2007)
found that FQI could not separate between burning and grazing effects on native prairie, even
though the prairies differed in native species richness.
33
The Jamison and Underwood (2008) study also fails to explain the scale at which data were
analyzed, which may affect comparisons between treatments. The study illustrates a nested plot
sampling strategy using 0.01, 0.1, 1.0, and 10 square meter plots. But it is not explained how or
whether the data were recorded and analyzed within the nested plots, and it appears that all the
data were analyzed at the largest plot scale. This large scale makes it difficult or impossible to
detect significant change in vegetation composition and structure that occur at small scales with
the onset of grazing, and therefore the PBG analysis is biased toward finding no significant
results. For example, a significant drop in abundance of a vulnerable plant species detected at ¼
meter square would not occur if it remained present but rare at the 10-square-meter square scale.
At the same time, a single increaser (a prairie generalist) could occur in the plot, thereby
increasing total richness. During the four-year monitoring program, there was no analysis of
change in individual species abundance between grazed and ungrazed treatments.
A large part of the PBG monitoring program dealt with measuring vegetative structure achieved
by grazing. Structure units were divided into classes of vegetation measured by height, bare
ground, litter, forb cover, and grass cover (Fuhlendorf and Engle 2004, Jamison and Underwood
2008). Importance was given to the classes of vegetation structure and not the species
composition within those classes. Therefore, results of PBG monitoring highlight the success of
increasing vegetation structural heterogeneity (Jamison and Underwood 2008) but there is no
consideration for species composition within those vegetation structures. All species are treated
equally regardless of a species’ conservation needs. For example, summer vegetation structure
consists of grazing increasers (plant species less palatable to cattle). These are generalist plant
species with broad ecological amplitude that are not restricted to prairies (Figs. 12, 13). While
the more conservative, obligate species are grazed and weakened, the more aggressive generalist
species are allowed to produce seeds, increase their vigor, and generally flourish (Fahnestock
and Knapp 1993, Damhoureyeh and Hartnett 1997) thus lowering the natural quality of the
prairie. (Refer to Figs. 12 and 13 and Table 3 that show prairie increasers due to cattle grazing.)
Fig. 12. Taberville Prairie PBG unit showing dominance by prairie generalist species. (Photo
taken August 26, 2009)
34
Fig. 13. Niawathe Prairie PBG unit dominated by ashy sunflower, an allelopathic prairie
generalist. (Photo taken August 26, 2010)
Table 4. Summer increaser species found in PBG units at Taberville Prairie Natural Area and
Niawathe Prairie Natural Area on July 26, 2010.
Achillea millefolium (Yarrow)
Ambrosia artemisiifolia (Common Ragweed)
Amorpha canescens (Lead Plant)
Baptisia alba (Wild White Indigo)
Baptisia bracteata var. leucophaea (Cream
Wild Indigo)
Ceanothus americanus (New Jersey Tea)
Diodia teres (Buttonweed)
Erigeron annuus (Daisy Fleabane)
Eupatorium perfoliatum (Common Boneset)
Euthamia graminifolia (Flat-topped
Goldenrod)
Helenium flexuosum (Sneezeweed)
Helianthus mollis (Ashy Sunflower)
Polygala sanguinea (Field Milkwort)
Pycnanthemum tenuifolium (Slender Mountain
Mint)
Rhus copallina (Winged Sumac)
Rubus sp. (Blackberry)
Rudbeckia hirta (Black-eyed Susan)
Ruellia humilis (Wild Petunia)
Solidago altissima (Tall Goldenrod)
Solidago rigida (Stiff Goldenrod)
Symphyotrichum pilosum (White Heath Aster)
Vernonia arkansana (Arkansas Ironweed)
Vernonia baldwinii (Western Ironweed)
As mentioned earlier, according to Jamison and Underwood (2008), Underwood (2010), and
Leahy and Underwood (2010), ―Current data analysis shows that patch-burn grazing has had no
significant impact on the vegetative community.‖ After reviewing the summer photos and list of
standing vegetation, it should be impossible to conceive that there has been no significant impact
on the natural quality of the prairies receiving PBG.
35
CONCLUSION
PBG is a very controversial and untested tool for managing prairies with high species richness
and abundance. Short-term results brought forward by MDC are not in peer-reviewed papers─
while the media releases extol the benefits of using cattle on prairies without explaining or
examining the disadvantages of such actions. Although native grazers once performed an
important function, along with fire, in promoting a dynamic prairie ecosystem on a landscape
scale, that process is difficult, if not impossible, to replicate with cattle in a fragmented
landscape. Prairies have been reduced to mere fragments of their former character, and
ecosystem management need to be adjusted to ensure that species diversity, life form, and
individual species are not lost.
Intense grazing on such small prairie fragments is not working. Burned patches are so small that
they do not hold the cattle, and the entire prairie is being grazed. Large landscapes are needed
where cattle can be kept on the recently burned patch for an appropriate time. The practice is best
for already degraded grasslands where it is possible to diversify vegetative structure for obligate
prairie birds while providing a grazing resource. It is not sound ecosystem management to use
PBG on small high quality prairies. These prairies should be preserved as baseline areas of high
quality ecosystems for comparison with other lower quality areas and their management. I am
very concerned that MDC, which manages almost 13,000 acres of remnant (unplowed) prairie
has, as of 2009, deployed PBG with cattle on 11 prairie conservation areas; that is 17% of the
prairie conservation areas that MDC manages (Leahy and Underwood 2010). Current plans by
the MDC prairie-chicken recovery team (October 2009) are to introduce PBG to additional
prairies that will result in 30% of all MDC’s public prairies being grazed. The prairies, as those
selected in the past for PBG, will likely be some of the largest prairies in the system thus
impacting the best examples of near landscape-level prairies that remain in the state. This is a
bold step to take, given that PBG is only a partially-researched and questionable method for
maintaining healthy, viable prairie ecosystems.
36
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