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A Paradigm Shift: Using as a Means to Achieve Ecological and Agricultural Objectives

Annotated Bibliography

Achieving Ecological & Agricultural Objectives

Stephen L. Thomforde 2013

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Introduction: A Paradigm Shift: Using Grazing as a Means to Achieve Ecological and Agricultural Objectives Over the past half century, modern has become a preeminent adversary to variety of special interests, including environmental, food health, soci-economic, and groups. Recently though, grazing has emerged as a way to maintain agricultural production while satisfying a variety of objectives associated with these interest groups. This paper is focused on the environmental impacts of grazing livestock, and in particular, on topics that include: biological diversity, nutrient regulation, , and . The thesis I explore assumes grazing is a critical process to maintain ecosystem integrity in -savanna ecosystems, and removing grazing, or processes that mimic grazing such as haying, sets in motion a cascade of feedbacks that cause these highly functional ecosystems to rapidly transition into dysfunctional ecosystems.

This research reviews scholarly articles on the evolution, history, , strategies and environmental impacts of grazing. This analysis allows us to describe grazing as an important process to grassland savanna integrity with beneficial impacts on , nutrient regulation, water quality, and numerous additional ecological attributes. We suggest land managers embrace grazing or making as a viable cost efficient means to achieve numerous ecological objectives, while breaking barriers between agriculture and environmental interest groups. In so doing we unify ecology and agriculture, to the mutual benefit of one another through grazing.

Obstacles to unifying agricultural and environmental groups involves antagonistic perceptions by both communities: environmentalist view grazing domestic animals as incompatible to their objectives and agriculture producers view grazing as non-profitable. These perceptions are reinforced by historic mismanagement of grazing animals often resulting in , and by agro-economic models based on high-input gross production instead of net returns. Old perceptions die hard, but advancements in ecological theory and research, renewed interests in local foodsheds, and the increasing socio-ecological costs associated petroleum based high-input agriculture have allowed once opposing forces, and environmentalist, to unite in ways that benefit the , the land and our communities.

The research reviewed is categorized: 1) evolution and ecology of grazing ecosystems, 2) grazing impacts on biodiversity, 3) grazing impacts on general ecological attributes such as nutrient regulation and water quality and, 4) grazing and environmental policy.

Synopsis of Articles: If we sum the acreage of plant communities that exhibit a strong graminoid component, including tropical and temperate grassland-savannas, semi-arid grass-shrublands, coastal plains, chaparral, tundra, parklands, and alpine , we find that grassland savanna systems historically covered 55-60% of the terrestrial planet. The names of these are as ancient as their human civilizations and include such places as the Africana Serengeti & Veld, the Eurasian Steppes and Heathlands, the South American Pampas, Cerrado, and Llanos, the

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Southern Mediterranean Dehesa, and the North American Great Plains, Palouse, Prairies, Savannas, Groves, and Openings.

These grassland-savanna ecosystems, especially true savanna, represent the most functional- productive terrestrial ecosystems ever to exist. Grassland-savannas grazing ecosystems emerge after the Cretaceous-Paleogene extinction 65 million years ago (mya), when flowering plants and refill the void once occupied by dinosaurs and non-flowering plants. Over the next several million years, flowering plants and coevolve in a grand symbiosis where and organism become mutually dependent upon one another. By the end of the Eocene 34 mya, major linages of grassland savanna plants and herbivores had emerged and by the early , 25 mya, the African, South and North American, and Eurasian continents were dominated by grassland savanna biotic communities composed of diverse plant guilds feeding diverse grazing guilds feeding diverse guilds. mammals, including , cervids, camels, beaver, apes, and other herbivores which in turn hunted by a diverse group of .

Through this grand evolving symbiosis of plants feeding animals, energy and matter flows became increasingly regulated through a set of biotic controls, in other words, organisms regulated nutrient flows to the mutual benefit of the entire biota. Stronger biotic regulation on energy flow equates to higher ecosystem function and production (E-FP). This is not coincidental but is rather the result of intra-species evolution, DNA linking across organisms in time and space, evolving the entire towards greater ecosystem fitness. It began 2.7 billion years ago, when ancient chloroplasts capture and regulate the flow of sunlight, radically transforming inorganic carbon into biochemical energy, glucose. Herbivory provides a mechanism to transform the energy into a higher trophic state, placing another set of bio-controls over energy and nutrient flow, thus increasing E-FP. Likewise, carnivory provides yet another transformation, more control, and greater E-FP. Longer food chains evolve, increasing order by exporting chaos (entropy) back to space. By passing energy to higher tropic levels, major nutrient cycles come under strong biotic regulation over the essential nutrients, including nitrogen, phosphorus and carbon cycles. By the time humans show up, 250, 000, years ago, grassland-savannas and grazing animals dominate the terrestrial planet.

At the beginning of the Antropocence The dominate plant communities were composed of edible angiosperms feeding herbivores a variety of products including; nectar, pollen, ediasomes, seeds, berries, nuts, , and tubers. In return, the herbivores performed services that benefited the plants, such as pollination, seed dispersal, and reduction of overgrowth to help the edible plants maintain community membership. Plant communities evolved to tolerate, embrace, and eventually becoming obligate to grazing, and later fire and grazing. Humans soon learn to manage grassland savannas in order to maximize potentials. Fire is employed to promote edibility and expand the range.

With grazing these ecosystems provision high quality food and fiber, stabilize soils, regulate nutrients, purify water, increase biological diversity, and sequester carbon. Without grazing these ecosystems no longer function properly and therefore do not provision any of the afore mentioned services, and in fact, without grazing, these ecosystems can actually accelerate soil

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erosion, carbon export to the atmosphere, nutrient slough, pollute waters, and supply no food or fiber to any living organism except maybe low quality fungi and bacteria.

The transition from functional to dysfunctional ecosystems due to the lack of grazing is a global phenomenon and marks a devolution of highly complex terrestrial ecosystems, anywhere land had been grazed for millions of years before Homo sapiens, and more recently by Homo sapiens who managed the landscape through fire to increase grazing. It has been said, the true mediated by fire is when fire was removed from the ecosystem and the plant community spins out of control. The same is true for grazing, and sense grazing preceded fire as the primary constraint on plant community configuration by several million years, the loss of grazing is far more perilous to ecosystem integrity than the loss of fire. Therefore, restoring the land to its most recent most functional configuration requires the restoration of both grazing and fire. by land no-longer grazed, includes our cherished conservation reserves and parks, where we prohibit grazing, but continue to fight an unsustainable battle to maintain a semblance of some native vegetation. The story which unfolds from the literature review shows us how we can enhance our conservation efforts through grazing, and other harvest processes including haymaking. In this scenario, we increase ecosystem integrity through agricultural production, while providing high quality food and fiber and jobs that accompany the local foodshed value added emerging markets. .

The following text summarizes 84 peer reviewed articles concerning the ecological benefits of grazing livestock. The articles are divided into five sections that include: 1) Evolution of Grazing Ecosystems, 2) Grazing Impacts on Biodiversity, 3) Environmental Impacts of Grazing, 4) Management for Ecological and Agricultural Objectives, 5) Policy, Programs, and Research Needs.

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Evolution of Grazing Ecosystems

1) Rise of the Grassland Biome, Central North-America Axelrod, D. (1985). Botanical Review, 51(2), 163-201. Summary: The author uses paleoecological evidence to explain the rise of the grassland biome in North America. Evidence includes paleo-pollen analysis, plant and animal fossils, current ranges for a variety of plant species, and disjunctive plant populations. Evidence indicates glasslands first emerged in the western portion of the North American continent, along the rain shadow created by the Cordillera uplift (Rocky Mountains) 40 million years ago (mya). Grasslands expand eastward into the Midwest during an arid period in the late Miocene early Pliocene 10 mya. Grasslands rapidly expand eastward, to the Atlantic states with the advent of humans and fire at the end of the Pleistocene. The author concludes the modern grassland biome is the product of feedbacks between an increasingly arid environment, vegetation, herbivorous animals, and humans using fire.

2) A Postulated Natural Origin for the Open Landscape of Upland Scotland Fenton, J. H. C. (2008). Plant Ecology & Diversity, 1(1), 115-127. Summary: This paper challenges the dominant ecological perception that the treeless Scottish uplands are a product of humans grazing livestock, tree cutting, and burning, and that without these disturbances, the Scottish highlands would have been forest. The paper investigates historical feedbacks between vegetation, soils, herbivores, fires and tree-felling to identify plausible factors to account for the open landscape without inferring human influence as the primary driver. The author proposes the current open state is equivalent to previous interglacial periods where expansion is followed by woodland regression. If this analysis is correct, upland Scottish could be one of the most natural landscapes in . This concept has major implications for Scottish Highland conservation planning, where to date forest ‘restoration’ is dominant narrative.

3) The Ecology of the Earth's Grazing Ecosystems Frank, D.A., McNaughton, S. J., Tracy, B. F. (1998). Bioscience, 48(7), 513-521 Summary: This paper summarizes the relationship between grassland vegetation and grazing animals. The authors conclude that are an important component of energy and nutrient flows in grazing ecosystems. When ungulates are removed from grasslands, the functional character of the system changes, edible plants are soon replaced by inedible plants, and the shifts from -carnivore to . The result is a less functional ecosystem.

4) The Origin of Grass-dominated Ecosystems Jacobs, B., Kingston, J., & Jacobs, L. (1999). Annals of the Missouri Botanical Garden, 86(2), 590-643. Summary: Approximately half of the Earth's vegetative cover comprises savannas, grasslands, and other graminoid-dominated ecosystems. Grasses are known from all continents except Antarctica. Fossil evidence and stable isotope analysis suggest five stages in the origin of grass- dominated ecosystems: (1) the late Paleocene origin of 55 mya, (2) the transition of Paleocene-Eocene forests into open woodland in the early Tertiary 45 mya, (3) an increase in C(3) grasses 35 mya, (4) the origin of C(4) grasses in the middle Miocene 15 mya, and (5) the

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spread of C(4) grass-dominated ecosystems in the late Miocene 7 mya. Herbivore morphology conducive to grass-dominated ecosystems first appears in South America at the Eocene- Oligocene boundary 35 mya, and later in northern continents in the early Miocene 20 mya. By 7 mya, savanna grassland grazing ecosystems are the most advanced and ecologically functional terrestrial ecosystems ever to have existed on the earth.

5) The Origins and Evolution of the North American Grassland Biome: The Story from the Hoofed Mammals Janis, C.M., Damuth, J., Theodora. 2002. Palaeogeography, Palaeoclimatology, Palaeoecology, Vol. 177, Issues 1–2. Summary: The authors suggest the North American grassland biome emerged 18 million years ago (mya) where the fossil record indicates a shift in mammal tooth formula from a diet change to a grazing diet. This suggests the South American and North America grasslands have coevolved with grazing animals for 45 to 18 mya respectively.

6) Grazing - Animals in , Plant Form, and Coevolution McNaughton, S.J. 1984. American Naturalist 124 (6), Pages: 863-886. Summary: The concept of the “Gazing ”as a plant community is introduced to the scientific community in this classic paper. Grazing lawns occur when herbivores frequent particular landscapes in a predictable time space pattern. For example, herbivores frequent shade created by open-grown trees during sunny hot summer days. The shade pools are subsequently subjected to periods of intense grazing. Over time, plant and animal communities associated with grazing lawns evolve particular traits that reinforce each other through a series of complex mutualistic feedbacks. The author concludes grazing lawns represent highly evolved biotic- communities, where plants and animals are dependent upon one another, in fact, plant species associated with grazing lawns can be considered “graze obligates”. Interestingly, the grazing lawn concept has not caught on in North America, where plant and animal relationships are viewed instead under the context of predator prey relationships.

7) Coevolution of Grasses and Herbivores Stebbins, G.L. 1981. Annals of the Missouri Botanical Garden, Vol. 68, No. 1, 1981 Summary: The author conducts a literature review to determine when biomes on different continents transitioned from forest communities with browsing animals to savanna grasslands with grazing animals. Evidence indicates grasses and herbivores mutualistically coevolved starting first in South America during the Eocene 55-45 million years ago (mya) and in North America 25 mya. The paper provides an excellent summary for the emergence of keystone grass and animal species.

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Grazing Impacts on Biodiversity

8) The Effect of Grazing on the Spatial Heterogeneity of Vegetation. Adler, P.B., Raff, D., and Lauenroth, W. 2001. Oecologia 128(4):465-479. Summary: This study suggests grazing alters the spatial heterogeneity of vegetation, creating a patchy pasture mosaic which in turn increases ecosystem function. This study attempts to model how and why grazing increases or decreases spatial heterogeneity. The study finds continuous and no grazing decreases heterogeneity while intermediate grazing increases heterogeneity. The study also indicates landscape attributes, such as shade pools and watering stations that constrain grazing frequency, intensity, and duration also increases spatial heterogeneity. In conclusion, how often a patch is grazed determines spatial heterogeneity of vegetation, but how often a site is gazed is determined by landscape patterns.

9) Plant Species Diversity and Grazing in the Scandinavian Mountains - Patterns and Processes at Different Spatial Scales Austrheim, G., and Eriksson, O. (2001). Ecography, 24(6), 683-695. Summary: There is a long tradition of grazing semi-domestic reindeer and in alpine and sub-alpine Scandinavian habitats. Current conservation ideology calls into question the practice of grazing and instead recommends grazing exclusion. This paper suggests the high plant diversity associated in Scandinavian mountain meadows is the result of humans grazing animals for thousands of years. The author concludes grazing is a key process for maintaining biodiversity in the Scandinavian mountains, and the practice of grazing needs to continue.

10) Farmland Biodiversity: Is Habitat Heterogeneity Key? Benton, T.G., Vickery, J.A., and Wilson, J.D. 2003. Trends in Ecology & Evolution 18(4):182- 188. Summary: This study examines the literature concerning agricultural intensification and the widespread decline in farmland biodiversity in temperate agricultural regions. The authors conclude the loss of ecological heterogeneity is a universal consequence of agricultural intensification. The author concludes that attempts to reverse declines in farmland biological diversity will include policy frameworks that benefit both the producer and biodiversity.

11) Establishing Grazing and Grazing-Excluded Patches Increases Plant and Invertebrate Diversity in a Mediterranean Oak Woodland Bugalho, M. N., Lecomte, X., Goncalves, M., Caldeira, M. C., and Branco, M. 2011. Forest Ecology and Management, 261(11), 2133-2139. Summary: Grazing is an important ecological process in Mediterranean ecosystems but, there is little information about grazing impacts on biodiversity. This study conducts an experiment to assess the impacts of grazing and grazing-exclusion on plant and invertebrate diversity in a Mediterranean evergreen oak woodland. While total diversity between the two treatments did not differ, the floristic composition between the two treatments differed significantly. Some plant species and invertebrate taxa were recorded exclusively in grazed or ungrazed plots. Management practices that maintain grazing and small scale grazing-excluded areas can increase habitat heterogeneity and promote plant and invertebrate diversity.

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12) Effects of on Nesting Ducks in California Carroll, L.C., Arnold, T.W., and Beam J.A. 2007. The Journal of Wildlife Management 71(3):902-905. Summary: This study challenges the current narrative concerning the detrimental impacts of grazing on waterfowl production. Duck nest success is compared between grazed and un-grazed units for two seasons in Central California. Results conclude no difference in duck nest survival between graze and un-graze units. In certain circumstances, grazing may enhance waterfowl production by creating corridors that allow newly hatched upland nesting waterfowl more efficient access to open water. Likewise, herbivore dung piles attract insects which serve as a key food component to young and molting waterfowl. The authors conclude grazing should be considered as a management procedure on Federal, State, and private waterfowl production lands.

13) Effects of Patch-burn Management on Dickcissel Nest Success in a Churchwell, R. T., Davis, C. A., Fuhlendorf, S. D., and Engle, D. M. (2008). Journal of Wildlife Management, 72(7), 1596-1604. Summary: Grassland bird populations have declined more dramatically than any other North American bird community. Grassland birds evolved within heterogeneous patchy biotic communities structured through interactions between fire and grazing. Current grassland management diminishes this patchiness while favoring homogenous biotic communities. For example, continuous grazing promotes homogeneous stands of short vegetation, while “natural” area management such as Conservation Reserve, favors homogenous stands of tall vegetation. The authors suggest management which promotes homogenous biotic communities at the expense of patchiness might be responsible for declines in grassland bird populations. The authors examine the impacts of burning and grazing (patch burn grazing) verses traditional management (annual burning or continuous grazing) on the reproductive success of the grassland bird dickcissels (Spiza americana) in tallgrass prairie in Oklahoma. Dickcissel nest success was higher in patch-burn grazed units than in traditional management units. The positive response of dickcissel nest success to patch-burn management provides further evidence that patch burn grazing offers a useful tool for grassland bird conservation and should be encouraged as a conservation strategy for grassland bird conservation.

14) Effects of Fire, Grazing and Topographic Variation on Vegetation Structure in Tallgrass Prairie. Collins, S. L., and Calabrese, L. B. (2012). Journal of Vegetation Science, 23(3), 563-575. Summary: This study identifies the impacts on plant diversity following 20 of years burning and 13 years of grazing. Results indicate species diversity is maximized in sites infrequently burned and grazed, while diversity was lowest on frequently burned and ungrazed sites. In general, grass cover was highest in infrequently burned ungrazed sites and lowest on frequently burned grazed sites, while forb richness was highest in infrequently burned and grazed sites. Frequent burning favored C4 grasses, which reduced the abundance of C3 forbs. Responses of dominant grasses and forbs to fire and grazing varied depending on topographic position. Community stability was positively correlated with species richness. The authors conclude a combination of bison grazing and periodic fire is necessary to maximize diversity and community stability.

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15) Avian Community Response to Vegetation and Structural Features in Grasslands Managed with Fire and Grazing. Coppedge, B.R., S.D. Fuhlendorf, W.C. Harrell and Engle D.M. 2008. Biological Conservation 141:1196-1203. Summary: This study compares bird communities between grazed and un-grazed, burned and unburned grasslands from 2001 to 2003 in Oklahoma. Bird diversity is higher in burned and grazed units at various stages of succession and lowest in units not grazed and not burned. Managers interested in grassland bird communities are encouraged to consider patch burn grazing management to increase both bird diversity and palatable forage. This study also examines the role of manmade structures, such as roads, stock-ponds and shelter-belts on bird community composition, and concludes pasture management to increase landscape heterogeneity in terms of vegetation and structure, correlates to increases bird diversity.

16) The Presence of Sheep Leads to Increases in Plant Diversity and Reductions in the Impact of Deer on Heather DeGabriel, J. L., Albon, S. D., Fielding, D. A., Riach, D. J., Westaway, S., and Irvine, R. J. (2011). Journal of Applied Ecology, 48(5), 1269-1277 Summary: Management of grazing herbivores is an important tool for maintaining biodiversity in many ecosystems. Mixed grazing by sheep and deer appears beneficial for increasing diversity and minimizing damage to heather in the uplands. Results indicate that reducing livestock may alter the impacts of wild grazers on their habitats and drive changes in diversity, whereas mixed grazing can enhance habitat quality and maintain plant diversity.

17) Livestock as Ecosystem Engineers for Grassland Bird Habitat in the Western Great Plains of North America Derner, J.D., W.K. Lauenroth, P. Stapp and D.J. Augustine. 2009. Ecology & Management 62(2):111-118. Summary: This study examines the potential for livestock to act as “ecological engineers” to achieve desired habitat modification for declining grassland bird populations. The research concludes using livestock as ecosystem engineers to modify vegetation is feasible and more research on using livestock to achieve desired grassland bird habitat in relationship to financial feasibility on public and private lands should be conducted.

18) Effect of Grazing a Species-Rich Mountain Pasture under Different Stocking Rates on the Dynamics of Diet Selection and Sward Structure Dumont, B., Garel, J. P., Ginane, C., Decuq, F., Farruggia, A., Pradel, P. (2007). Animal, 1(7), 1042-1052. Summary: Stocking rate is a key management variable influencing the structure and composition of . Few studies analyzed seasonal patterns of pasture use. This study examines 3 different stocking rates over 3 years. Data included diet selection, plot use, and impact on sward structure and quality in a species-rich mountain pasture of central France. Heifers selected for legumes & forbs, and against reproductive grass whatever the stocking rate or season. Neither diet quality nor individual animal performance was affected by the stocking rates. Sward heterogeneity was highest in moderately grazed plots, suggesting a potential optimal balance between livestock production and conservation management.

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19) Restoring Heterogeneity on : Ecosystem Management Based on Evolutionary Grazing Patterns. 2001. Fuhlendorf, S.D. and Engle D.M.. 2001. BioScience 51(8):625-632. Summary This paper proposes a pasture paradigm to enhance diversity instead of homogeneity on rangelands grazed by livestock. The concept implied is called “patch-burn grazing” and is designed to mimic historic interactions between fire and large herbivores. The two disturbances, fire and grazing are constrained by time and edaphic attributes to create a landscape patchiness of shifting biotic communities that enhance biodiversity, productivity, and ecosystem function. The authors suggest patch burn grazing replace the current “uniform disturbance” pasture management narrative in areas with multiple objectives such as biodiversity and agricultural production.

20) Application of the Fire—Grazing Interaction to Restore a Shifting Mosaic on Tallgrass Prairie. Fuhlendorf, S.D., D.M. Engle. 2004. Journal of Applied Ecology 41(4):604-614. Summary: This paper explores feedbacks between fire and grazing that creates a shifting vegetative mosaic that increases biodiversity, productivity, and ecosystem function in Oklahoma grasslands. This research attempts to restore a historic disturbance regime, where landscape patterns influence fire intensities and subsequently grazing intensities. Results show patch-burn grazing management increases community heterogeneity, biodiversity, productivity and ecosystem function. The authors suggests patch-burn grazing be employed on lands seeking to satisfy biodiversity and agricultural production objectives.

21) Should Heterogeneity be the Basis for Conservation? Grassland Bird Response to Fire and Grazing. Fuhlendorf, S.D., Harrell, W.C., Engle, D.M., Hamilton, R.G., Davis, C.A., Leslie, D.M. Jr. 2006. Ecological Applications 16(5):1706-1716. Summary: This paper examines the effects of “patch-burn grazing” on grassland bird diversity in tallgrass prairie. The results indicate different plant species associate with different intensities of fire and grazing and different bird species correspond with different vegetation. Some plant and bird species show a preference to intensely burned and grazed treatments, while other plant and bird species show preference to infrequently burned and grazed treatments, and still other plant and bird species seem to prefer in-between intensities of fire and herbivory. The authors conclude that agricultural (i.e. grazing) and ecological objectives (i.e. bird diversity) can be achieved through management strategies that mimic historic shifting disturbance regimes that include both fire and herbivory.

22) Pyric Herbivory: Rewilding Landscapes Through the Recoupling of Fire and Grazing Fuhlendorf, S. D., Engle, D. M., Kerby, J., Hamilton, R. (2009). Conservation Biology, 23(3), 588-598. Summary: This study examines the relationship between fire and grazing over time and space. The authors conclude the ecological interaction of fire and grazing are dependent opon one another and over time, create a shifting mosaic were community patches vary in composition depending upon the time since the last fire and or grazing event occurred. The authors call this

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process pyric herbivory and conclude grazing and fire through a series of positive and negative feedbacks establish a predictable burning-grazing pattern on the landscape. 23) Effects of Bison Grazing, Fire, and Topography on Floristic Diversity in Tallgrass Prairie Hartnett, D., Hickman, K., Walter, L. (1996). Journal of Range Management, 49(5), 413-420. Summary: The authors sample plant diversity on grazed and ungrazed sites subjected to different fire frequencies in the Konza Prairie in northeast Kansas. The objective was to determine the effects of bison grazing on plant community composition in sites with contrasting fire frequencies. The study found some plant species increased and some species decreased with grazing. Total diversity was significantly higher in grazed sites versus ungrazed sites. Increases in plant diversity associated with bison grazing were greater in annually burned than occasionally burned sites.

24) Diversity and Invasion: Implications for Conservation. Hobbs, R.J. L.F. Huenneke. 1992. Conservation Biology 6(3):324-337. Summary: This paper summarizes how different disturbance regimes (i.e. fire, grazing, soil disturbance, and nutrient additions) affect plant diversity. Disturbance regimes that closely mimic historic disturbance regimes tend to maintain intact functional diverse ecosystems. Likewise, disturbance regimes that differ from historic regimes, including type of disturbance, intensity, frequency and duration can decrease ecosystem integrity, function, and diversity. Ecosystems outside historic disturbance patterns are vulnerable to invasion by undesirable species and subsequent rapid transitions from functional to dysfunctional ecosystems.

25) Grazers, browsers, and Fire Influence the Extent and Spatial Pattern of Tree Cover in the Serengeti Holdo, R. M., Holt, R. D., Fryxell, J. M. (2009). Ecological Applications, 19(1), 95-109. Summary: African savanna acts as a model to help us better understand how savanna ecosystems functioned prior to intensive antropocation. Some argue African savannas are different than temperate savannas of North America and Eurasia; however, both systems are adapted to predictable seasonal climates: African systems senesce during hot dry periods, temperate savannas senesce during cold dry periods, and animals in both systems adjust their movements accordingly. This study develops a dynamic simulation model to better understand feedbacks between vegetation, fire, and herbivores. Results show grazers in open migratory ecosystems, can regulate the impact of fire and thus exert strong controls on landscape tree patterns.

26) Herbivore-induced Coexistence of Competing Plant Species Ishii, R., Crawley, M. J. (2011). Journal of Theoretical Biology, 268(1), 50-61. Summary: This paper uses a lottery model to understand feedbacks between two competing plant species, one palatable and the other non-palatable, in a homogeneous habitat grazed by large herbivores. The non-palatable species suffers from low reproductive success due to trade- offs for being non-palatable. Coexistence of the two plants cannot occur when the herbivore density is very low; the palatable plant always wins, or when the herbivore density is very high; the non-palatable plant always wins. Intermediate herbivore densities facilitate plant coexistence, even in a homogeneous environment. Herbivore forage-selection depends on average palatability and both plant populations are stabilized and coexistence is promoted. The authors conclude

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biodiversity objectives in grasslands are dependent on herbivore identity, density, duration and frequency.

27) Direct and Indirect Effects of Livestock Grazing Intensity on Processes Regulating Grassland Bird Populations. Johnson, T.N. 2011. Dissertation. Summary: This dissertation examines impacts of grazing intensity on vegetation structure and grassland songbird demography in a Northwest USA bunch-grass prairie. Different treatments receive different intensities of grazing. Results show songbird diversity does not change between grazing intensity, but songbird community composition differs significantly between treatments. This suggests different songbird species prefer different vegetation structure resulting from different grazing intensities. The research also identifies changes in songbird food (i.e. insects) quality, with declines in heavily grazed paddocks leading to nesting failures. The research concludes by suggesting good grazing management can maintain diverse grassland bird populations and agriculture production.

28) Restoring Tallgrass Prairie and Grassland Bird Populations in Tall Fescue Pastures with Winter Grazing. Johnson, T.N. Sandercock, B.K. 2010. Rangeland Ecology & Management 63(6):679-688. Summary: This paper examines the potential to use grazing as a tool to restore warm season prairie plant species and how this might impact grassland bird communities. Experimental pastures are dominated by tall fescue (Schedonorus phoenix), a cool season exotic grass species. Treatments include: 1) grazing livestock year around so both cool and warm season species are defoliated and 2) grazing livestock only during the cool season so only the cool season species are defoliated. The experiment runs for five years. Results show cool season grazing significantly increases warm season prairie plant species dominance. Bird species respond differently; some species prefer continuous grazing while other species benefit from seasonal grazing. The author concludes that grazing and cessation of can provide an effective restoration tool for rangeland with objectives for both agriculture production and biodiversity.

29) Grazing Impact on Plant Spatial Distribution and Community Composition Kohyani, P. T., Bossuyt, B., Bonte, D., Hoffmann, M. (2011). Plant Ecology and Evolution, 144(1), 19-28. Summary: Land managers are increasingly interested in using grazing animals to help conserve the few remaining natural grasslands. In theory, grazing livestock helps prevent invasion and dominance by late successional low-quality plant species (i.e. plants which provide few ecosystem services such as food and fiber production, soil building, water infiltration and purification, and nutrient regulation). This study tests the effects of herbivores to reduce dominance by late successional low-quality species. Results indicate grazing is effective at reducing community dominance by late successional low-quality species while at the same time facilitating the emergent of less competitive high-quality plant species, and increasing total biological diversity.

30) How much does Grazing-induced Heterogeneity Impact Plant Diversity in Wet Grasslands? Marion, B., Bonis, A., Bouzille, J. (2010). Ecoscience, 17(3), 229-239.

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Summary: While much research exists indicating the positive impacts of grazing on grassland heterogeneity and biodiversity in plant communities, the mechanisms linked to this relationship remain unclear. This study examines 3 different wet-grassland communities situated along the French Atlantic that have been historically grazed by horses and cattle. Results show a positive correlation between grazing, patchiness, and species richness. The authors conclude grazing- induced patchiness entirely explained the increase in plant richness, and partially explained the recruitment of new species.

31) Rabbit Grazing as the Major Source of Intercanopy Heterogeneity in a Juniper Shrubland Marko, G., Onodi, G., Kertesz, M., Altbaecker, V. (2011). Arid Land Research and Management, 25(2), 176-193. Summary: Semi-arid shrublands are fire dependent communities; however, in recent time fire within these communities has increasingly become catastrophic: dense grass-shrub vegetation ignites, blows-up, and then spreads uncontrollably. Shrubs are more prone to ignition when intercanopy vegetation accumulates and contributes to excessive fuel loads. This study occurs in a semi-arid shrub community prone to high fire risk, where grass density under red cedars contributes high loads. The authors examine the relative significance of 3 main factors contributing to intercanopy plant cover and fuel loads including: allelopathy, shading, and herbivory. Test plots either contained or excluded grazing rabbits. Results indicate that neither shading nor allelopathy are as important as herbivory for reducing plant cover and fuel loads. The authors conclude local herbivore activity can affect the spatial heterogeneity of combustible materials, and moderate rabbit grazing can reduce catastrophic fire.

32) Long-term Impacts of Extensive Grazing and Abandonment on the Species Composition, Richness, Diversity and Productivity of Agricultural Grassland Marriot, C.A., Hood, K., Fisher J.M., Pakeman, R.J. 2009. Agriculture, Ecosystems & Environment 134(3-4):190-200. Summary: This paper examines the effectiveness of grassland extensification on addressing declines in biodiversity in agricultural landscapes. The study compares productivity, diversity, and species composition between grazed and ungrazed grasslands. Results indicate good grazing can maintain productivity, increase biodiversity, and maintain desirable species composition. Abandoned land shows no decline in biodiversity, but does show a significant change in species composition, with a trend towards rank low-quality weedy species, suggesting proper grazing promotes high quality vegetation.

33) Disturbance Response in Vegetation Towards a Global Perspective on Functional Traits McIntyre, S., Lavorel, S., Landsberg, J., Forbes, T. (1999). Journal of Vegetation Science, 10(5), 621-630. Summary: Functional trait analysis of plant communities provides an informative description as to why certain species inhabit a particular space in a particular time. Plants with similar functional traits inhabit similar environmental spaces. Functional trait diversity provides a more useful approach to quantifying biodiversity and is commonly employed in Europe and Australia, but has failed to gain acceptance in North America. This paper attempts to categorize plant species into functional groups based on their resilience to various grazing intensities. Increases

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in functional diversity, which equates to increases in ecosystem function and service, theoretically occurs in paddocks subjected to intermediate intensities of grazing at predictable times. The authors identify 3 functional groups tolerant to three intensities of grazing pressure and include: heavy, moderate, and low grazing groups, in both cool and warm seasons. The authors conclude functional trait analysis should provide explicit descriptions of evolutionary and ecological traits from a global perspective.

34) Spatial Heterogeneity and Plant Species Richness at Different Spatial Scales Under Rabbit Grazing Olofsson, J., de Mazancourt, C., & Crawley, M.J. 2008. Oecologia (2008) 156:825–834 Summary: This paper documents increases in spatial heterogeneity and species richness in a rabbit-grazed grassland. The research examines the relationship between spatial patterns of grazing intensity, rabbit droppings, plant height, plant biomass, soil water, and nutrient cycling in grazed and ungrazed treatments in southern England grasslands. Results indicate rabbit grazed sites contain 2 different plant assemblages: 1) heavily grazed patches with low vegetation (lawns) with high nutrient soils, and 2) ungrazed patches with high vegetation and nutrient-poor soils (tussocks). Rabbit grazing increases species richness at all spatial scales. Species richness was negatively correlated with plant height and positively correlated with diverse vegetation height, both low and high vegetation.

35) Different Grazing Strategies are Necessary to Conserve Endangered Grassland Birds in Short and Tall Salty Grasslands of the Flooding Pampas Pablo Isacch, J., and Augusto Cardoni, D. (2011). Condor, 113(4), 724-734. Summary: This study examines how grazing affects bird assemblages in coastal salt-grasslands in Argentina. Four different types of grazing (rotational, continuous, winter grazing, and graze exclusions) are examined. Results show different species of birds prefer different types of grazing. The authors propose diverse avian communities will require a system of heterogeneous grazing systems that optimizes both agri-production and conservation of grassland birds.

36) Comparison of Riparian Plant Communities under Four Land Management Systems in Southwestern Wisconsin. Paine, L.K., Ribic, C.A. 2002. Agriculture, Ecosystems & Environment 92(1):93-105. Summary: This study compares riparian plant communities under four types of management: 1) continuous grazing, 2) rotational grazing, 3) woody buffer strip, and 4) grassed buffer strip. Results indicate plant diversity is highest in woody buffer strip, rotational, and continuous grazing management regimes. Less desirable species, such as reed canary grass, display higher dominance in grassed and woody buffer strips, and are nearly absent in continuous and rotational grazing treatments. Native plant species display a higher frequency in both rotational and continuous grazing units. The authors conclude well managed grazing can achieve both agricultural production and ecosystem integrity objectives.

37) Another Tool in the Toolbox? Using Fire and Grazing to Promote Bird Diversity in Highly Fragmented Landscapes. Pillsbury, F.C., Miller, J.R., Debinski, D.M., & Engle, D.M. 2011. Ecosphere 2(3):Article 28. Summary: Patch-burn grazing (PBG) can increase grassland bird biodiversity in extensive grassland landscapes (i.e. landscapes dominated by un-fragmented grasslands); however the

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ability for PBG to amplify grassland bird diversity in fragmented landscapes (i.e. landscapes dominated by annual crops) is not understood. This study indicates restoration of diverse grassland bird communities in fragmented landscapes are less dependent on employment of PBG and more dependent on landscape context. The authors suggest restoration of diverse grassland bird communities in fragmented landscapes requires a reversal in fragmentation first and implementation of PBG second.

38) Grassland Bird Responses to Land Management in the Largest Remaining Tallgrass Prairie. Rahmig, C.J., Jensen W.E., & With, K.A. 2009. Conservation Biology 23(2):420-432. Summary: This paper examines impacts of grazing on grassland bird community composition in the Flint Hills of Kansas. Bird surveys occur in grazed, hayed, and CRP treatments. Results indicate the lowest bird diversity is correlated with CRP fields and different bird species prefer different management techniques. The author concludes diversification of land management, to include grazing, burning, resting, and haying would serve best to restore diverse grassland bird communities in the Flint Hills landscape.

39) Grassland Birds Associated with Agricultural Riparian Practices in Southwestern Wisconsin. Renfrew, R.B., Ribic C.A. 2001. Journal of Range Management 54(5):546-552. Summary: This paper examines four common types of land management impacts on bird diversity in riparian landscapes in Southwest, Wisconsin. The four types of land management include: 1) row crop production, 2) rotational grazing, 3) continuous grazing, and 4) grassed buffer strips. Results show no difference between bird diversity between land use types; however, bird species of management concerns are found more frequently in both grazing types, rotational and continuous continuous and rotational, but rarely in buffer strip and row crop land management types. The authors conclude different types of bird species prefer different types of vegetation associated with different types of land management.

40) The Influence of Grazing Intensity and Landscape Composition on the Diversity and Abundance of Flower-visiting Insects Sjodin, N.E., Bengtsson, J., Ekbom, B. 2008. Journal of Applied Ecology 45(3):763-772. Summary: This study compares insect pollinator diversity under three different grazing intensities: 1) un-grazed, 2) moderate grazing, and 3) intense grazing in both extensive and fragmented landscapes. Results seem to indicate different types of pollinators prefer different grazing intensities; however, how different grazing intensities are arranged on the landscape seems more important to pollinator diversity then just different grazing intensities. The authors suggest grazing plans to encourage insect pollinator diversity should be developed at the landscape context and not for the individual pasture.

41) Feedback Loops in Ecological Hierarchies Following Urine Deposition in Tallgrass Prairie Steinauer, E., & Collins, S. (2001). Ecology, 82(5), 1319-1329. Summary: Ecologists often predict large-scale factors constrain small-scale factors, but the potential for small-scale events to impact large-scale structure is unclear. This study examines the effects of highly localized urine deposition on large-scale vegetation structure and

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composition in tallgrass prairie, and if urine deposition, plant community response, and grazing are related to one another through a series of feedbacks. Results indicate bison grazing was more intense on urine patches than off urine patches. Also, grazed patches on urine deposition sites expanded well beyond the area of urine deposition. The combination of urine patches plus grazing produced unique large-scale vegetation patches. Bison preferentially grazed urine patches, which eventually became “grazing lawns” that in turn attracted more grazing, thus establishing a positive feedback loop. The authors conclude urine patches are an example of a small-scale disturbance that constrains large-scale patch structure in tallgrass prairie. While this study identifies a unique positive feedback between urine deposition and grazing, the conclusion suggesting a small scale disturbance of urine patches constrains large scale vegetation patterns fails to consider movement is constrained by landscape features such as river crossings, saddles, shade pools, canyons, and etc. The landscape context allows us to understand how grazing animals choose preferential grazing lawns. In this case a “larger” feature, the landscape, constrains a smaller feature, urine patches.

42) The Relative Importance of Grazing Stock Type and Grazing Intensity for Conservation of Mesotrophic ‘Old ’ Pasture. Stewart, G.B. and A.S. Pullin. 2008. Journal for Nature Conservation 16(3):175-185. Summary: This study examines the potential of grazing livestock to maintain rare grassland communities in Britain that are threatened by conversion into row crop production and “improved” pasture. The authors conduct a literature review to conclude a significant lack of research makes it difficult to draw any general conclusions as to which type of livestock will achieve optimal conservation objectives. The only discernible pattern occurs between grazing intensity and vegetation composition where the evidence suggests intermediate grazing maximizes species richness. The authors suggest future research collect more accurate data on grazing intensities by different types of livestock in relationship to plant community composition.

43) Vegetation Trends in Tallgrass Prairie from Bison and Cattle Grazing Towne, E., Hartnett, D., Cochran, R. 2005. Ecological Applications, 15(5), 1550-1559. Summary: This paper summarizes a 10-year study to compare the differences in vegetation change between cattle and bison grazed treatments in a Kansas, USA tallgrass prairie. All treatments were burned and grazed and stocking rates were considered moderate. Grazing pressure was held constant by matching animal body mass in all pastures each year. Results show bison and cattle differentially modify vegetation composition and structure, but overall, plant communities in bison and cattle pastures were 85% similar after 10 years. The authors conclude measurable differences between cattle and bison-grazed pastures in tallgrass prairie are typically in response to contributing factors, such as stocking rates, frequencies, intensity and duration rather than differences between herbivore species.

44) Influence of Grazing and Fire Frequency on Small-scale Plant Community Structure and Resource Variability in Native Tallgrass Prairie Veen, G. F., Blair, J. M., Smith, M. D., Collins, S. L. 2008. Oikos, 117(6), 859-866. Summary: Grazing and fire are important forces affecting resource availability and plant community composition. It is not clear whether changes in community structure are the effects of disturbance (i.e. grazing and fire) or the indirect effects brought about by changes in resource

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availability (i.e. nutrients and sunlight). This research conducts a study to determine the effects of long-term fire and grazing regimes by bison on plant community structure and resource variability. Results show grazing increased light and nitrogen availability, reduced C-4 grass dominance, and increased species richness, diversity and heterogeneity. In contrast, annual fire increased C-4 grass dominance and decreased species richness and diversity, particularly in absence of grazing, but had no effect resource availability. The authors conclude the direct impacts of grazing and fire had more impact on community composition and structure than did the indirect effects of resource availability. The author’s conclusion is justified; however, it depends on the temporal and spatial scale we choose to observe the system. If we change scale, the dominant set of controls over community composition and structure, fire and grazing in this case, switch and resource availability becomes the constraining factor over plant community composition and structure.

45) Diet Selection Variation of a Large Herbivore in a Feeding Experiment with Increasing Species Numbers and Different Plant Functional Group Combinations Wang, L., Wang, D., Liu, J., Huang, Y., & Hodgkinson, K. C. 2011. Acta Oecologica- International Journal of Ecology, 37(3), 263-268. Summary: This study exams the impact of sheep grazing on plant functional diversity (e.g. plant guilds such as: spring ephemeral, cool season, warm season, graminoid herbaceous and so forth). The authors assume good grazing management can maintain high levels of plant functional diversity, but this research examines the role of plant functional diversity’s influence on grazing patterns. The experiment exposes sheep to increasingly higher levels of plant functional diversity. Results show preferential grazing declines as plant biodiversity increases, indicating a negative feedback between selectivity and diversity. In conclusion, the authors suggest that high levels of biodiversity tend to decrease selectivity by sheep while promoting uniform utilization of pasture which in turn reinforces a high level of diversity.

46) Megaherbivores and Southern Appalachian Grass Balds Weigl, P., & Knowles, T. (1995). Growth and Change, 26(3), 365-382. Summary: This study examines the persistence of high altitude treeless grass “balds” in the Southern Appalachians. The balds are historically described in both the Amerindian oral tradition and early accounts by early European settlers. Modernization of agriculture led to the abandonment of the balds, and subsequently, the balds are rapidly transitioning from open meadows into closed woodland. Despite the assemblage of rare and unique plants, the balds receive little conservation attention because they are considered a human artifact of tree felling. The authors conduct a review of literature to conclude the balds were a natural feature created by high intensity grazing over several million years, and most recently maintained as grazing lawns by Amerindians using fire. The authors conclude by suggesting the balds are worthy of conservation and grazing animals offers a viable management strategy.

Environmental Impacts of Grazing

47) Comparing the Environmental Impacts of Pasture-Based and Confinement-Based Dairy Systems in Nova Scotia (Canada) Using Life Cycle Assessment. Arsenault, N., Tyedmyers, P., Fredeen, A. 2009. International Journal of Agricultural 7(1):19-41.

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Summary: This study conducts a life cycle assessment (LCA) to compare environmental impacts between grazing and confinement dairy systems in Nova Scotia, Canada. Data on material and energy inputs and outputs are compared for 11 categories, such as the use of concentrate feeds, N , transport fuels, and land-use footprint. Surprisingly, grazing cows for five months per season (typical grazing periodicity in Nova Scotia) showed little overall environmental benefit compared to confinement. The authors conclude these findings are due to the greater amount of land (footprint) utilized by grazing verse confinement systems. While the conclusion suggests there’s little difference between energy inputs and outputs between the two different grazing systems, the study fails to include an ecological integrity index to compare the external environmental impacts between confinement and grazing.

48) The Impacts of Grazing Animals on the Quality of Soils, Vegetation, and Surface Waters in Intensively Managed Grasslands. Bilotta, G.S., R.E. Brazier, Haygarth, P.M. 2007. Advances in 94:237-280. Summary: This paper conducts a literature review concerning the impacts of grazing on soil and water quality. The review concludes well managed grazing has beneficial soil and water quality impacts, but intensive grazing can have negative soil water quality impacts. Causes and consequences of degradation are discussed and solutions to problems proposed.

49) Farm returns to carbon credit creation with intensive rotational grazing Bosch, D.J., Stephenson, K., Groover G., Hutchins, G. 2008. Journal of Soil and Water Conservation 63(2):91-98. Summary: This study compares carbon sequestration rates between rotational and conventional grazing systems. Carbon sequestration rates increase for intensive rotational grazing; however, current carbon offsets under rotational grazing do not warrant financial carbon-credit incentives enough to switch from conventional to managed grazing in Eastern USA livestock operations.

50) Environmental Impacts of grazed pastures. Eriksen, J., Ledgard, S., Lou, J., Schils, R., Rasmussen, J. 2010. Grassland Science in Europe 15:880-890. Summary: This study examines cycling rates and residence times for nitrogen (N) and (CH4) between grazed and confined livestock operations. The study concludes N in animal excreta can be high in localized patches which under poor management can increase the risk of N losses to waterways and the atmosphere; however, under good grazing management N can be recycled between forage and livestock to form a closed loop that decreases N loss. Management strategies to induce closed N loop cycling are discussed. Also, the research shows grazing can reduce CH3 emissions. In conclusion, good pasture management can reduce negative environmental impacts associated with N and CH4 loss from pasture systems compared to confinement systems.

51) Sequestration in Grazing Lands: Societal Benefits and Policy Implications. Follett, R.F., Reed, D.A. 2010. Rangeland Ecology & Management 63(1):4-15. Summary: This study examines the potential for pastures to act as a carbon sink. Carbon sequestration rates are tested in both grazed and un-grazed grasslands. Evidence suggests good pasture management offers a viable option to sequester and store atmospheric CO2. The authors conclude by suggesting that because grazing can sequester and act as a long term sink for CO2,

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and the numerous other positive environmental benefits associated with grazing, government environmental and agricultural agencies should establish policy and programs to encourage grazing.

52) Consumer Control of Grassland Plant Production Frank, D.A., Kuns, M.M., Guido, D.R. 2002. Ecology, 83(3), 2002, pp. 602–606 Summary: The authors conduct field research to determine the impact of herbivory from migrating ungulates on whole-plant net primary production. The authors measure both net above ground production (NAP) and net below ground production (NBP) from grazed and ungrazed treatments in Yellowstone National Park. Results indicate grazing stimulated aboveground, belowground, and whole-plant productivity by 21%, 35%, and 32%, respectively. Below ground production of root biomass was stimulated by grazing seven times more than above ground leaf and stem production. These results suggest historic migratory ungulates that grazed similar spaces in similar seasonalities, at similar frequencies, intensities, and durations, allowed the plant community evolve in ways that incorporate the disturbance to maximize ecosystem function and production, a process termed “pulsing” by H.T Odum. The extensive below ground root production might explain the phenomenon of organic-rich mollisols development in global savanna-grassland systems. Also, extensive below ground production would provide an effective sink for carbon, which may have reinforced Pleistocene glaciation

52) Grazing Impacts on Soil Carbon and Microbial Communities in a Mixed-Grass Ecosystem. Ingram, L.J., Stahl, P.D., Schuman, G.E., Buyer, J.S., Vance, G.F., Ganjegunte, G.K., Welker, J.M., Derner, J.D. 2008. Society of America Journal 72(4):939-948. Summary: This study examines the effects of different grazing intensities on soil carbon, nitrogen, and microbial communities. Treatments include no grazing, light grazing, and continuous grazing. Results show soil carbon increases in un-grazed and lightly grazed treatments, soil nitrogen levels increased in un-grazed and lightly grazed treatments and declined in continuously grazed treatments. The only change in microbial community composition occurs in continuously grazed treatments and only after prolonged drought. The authors’ conclude the relationship between grazing, soil carbon storage, and soil nitrogen are complex and change according to the spatial and temporal scale of observation. Likewise, soil microbial composition seems to be more influenced by abiotic factors, such as climate, than by biotic factors such as grazing; however, the complex array of feedbacks constraining microbial community configuration is difficult to understand in short time periods in small plots.

53) Grazing: A Natural Component of Grassland Ecozone Riparian Systems LaForge, K. 2004. Agriculture and Agri-Food Canada, Prairie Farm Rehabilitation Administration document Summary: The author concludes grazing ungulates are a natural feature of riparian grassland ecosystems. Unmanaged grazing can degrade riparian ecosystems, but properly managed grazing can mimic patterns of native grazing ungulates and improve riparian health and function. Good management requires developing site specific grazing plans.

56) A Framework to Predict the Effects of Livestock Grazing and Grazing Exclusion on

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Conservation Values in Natural Ecosystems in Australia Lunt, I.D., Eldridge, D.J., Morgan, J.W., Witt, G.B. 2007. Australian Journal of 54(4):401-415. Summary: Australian grasslands are unique in that they evolved in absence of large grazing herbivores. Introduced livestock have severely damaged many Australian landscapes; however, livestock are still used in some regions to maintain ecological integrity. This paper constructs a framework to inform natural resource managers on when grazing might be beneficial or detrimental to any particular landscape. The framework suggests grazing exclusion for intact ecosystems with shallow soils. The framework also suggests grazing be employed on lands that require biomass control, where grazing can prevent invasion by undesirable species, and when grazing can enhance biodiversity. 57) Grass Versus Trees: Managing Riparian Areas to Benefit Streams of Central North America. Lyons, J., Trimble, S.W., Paine, L.K. 2000. Journal of the American Water Resources Association 36(4):919-930. Summary: Forestation is common conservation practice along riparian areas in agricultural lands in central North America. Trees and shrubs can provide benefits to streams, but this type of management removes agriculture land from production. This paper examines the potential benefits of grassy riparian buffer strips. The study concludes grassy riparian buffer strips might be more effective in reducing erosion and trapping sediments than wooded buffers. Maintenance of grassy riparian vegetation requires management such as mowing, haying, or grazing to promote dense turfs. The authors suggest grassy buffer strips have potential to restore degraded stream ecosystems while still producing agricultural products.

58) Influence of Intensive Rotational Grazing on Bank Erosion, Fish Habitat Quality, and Fish Communities in Southwestern Wisconsin Trout Streams. Lyons, J., Weigel, B.M, Paine, L.K., Undersander, D.J. 2006. Journal of Soil and Water Conservation 55(3):271-276. Summary: This paper examines the potential for rotational grazing to rehabilitate degraded stream banks in agricultural regions of Central, North America. This study compares stream banks managed by grassed buffer strips, rotational grazing, continuous grazing, and wooded stream banks for their ability to reduce erosion and enhance fish biotic integrity indexes. Results indicate grassed buffer strips and rotational grazing provide effective management strategies to rehabilitate stream banks, reduce sediment inputs, and enhance fish biotic integrity indices.

59) Pathways of Grazing Effects on Soil Organic Carbon and Nitrogen. Pineiro, G., Paruelo, J.M., Oesterheld, O., Jobaggy, E.G. 2010. Rangeland Ecology and Management 63(1):109-119. Summary: This paper examines the impacts of grazing on the ability of soil to sequester atmospheric CO2. Results indicate carbon sequestration is more complex than can be explained by any one general model. Carbon dioxide sequestration rates are influenced by many factors including the nitrogen cycle, precipitation patterns, and soil bulk densities. Still, the authors’ conclude, in most cases, well managed grazing can increase both pasture productivity and CO2 sequestration rates, especially in conjunction with management procedures that impose strong controls on nitrogen cycling.

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60) Grazing Can Reduce the Environmental Impact of Dairy Production Systems. Rotz, C.A., Soder, K.J., Skinner, R.H., Dell, C.J., Kleinman, P.J., Schmidt, J.P., Bryant, R.B. 2009. Forage and Grazinglands. Summary: This study compares the environmental footprint of three different Pennsylvania dairy operations: 1) total confinement based production, 2) summer pasture - winter confinement production, and 3) summer pasture and winter forage production. Results indicate the summer pasture and winter forage production system had the lowest environmental impacts, reducing by 87%, sediment bound and soluble phosphorus losses by 80%, and reducing carbon output by 80%. The authors conclude environmental benefits of grass-based dairy systems should be used to encourage expansion of pasture/forage dairy operations.

Management for Ecological & Agricultural Objectives

61) Identification and Creation of Optimum Habitat Conditions for Livestock. Bailey, D.W. 2005. Rangeland Ecology and Management 58(2):109-118. Summary: Optimum Habitat Condition (OHC) is a concept used by wildlife managers to maximize target populations (e.g. ). The OHC model suggests animal performance is greater in heterogeneous landscape, especially at the lower end of . This study models OHC for livestock in pasture management. In order to maximize pasture livestock performance, managers need to consider both abiotic factors, such as topography, water availability, and thermal cover, and biotic factors, such as forage quality and quantity, spatial grazing preferences and animal performance. Managers can improve livestock habitat conditions by modifying pasture features, such as water systems, thermal regulation systems (both for warmth and cooling), and by changing pasture features through burning, fertilizing, varying stocking rates, and grazing intensities. Managers should also utilize livestock adapted to specific pasture conditions. Finally, the OHC model suggests managers need to employ multiple management practices to optimize use of livestock habitat.

62) Utilization of Heterogeneous Grasslands by Domestic Herbivores: Theory to Management. Bailey, D.W., Dumont, B., WallisDeVries, M.F. 1998. Annales de Zootechnie 47(5-6):321-333. Summary: Herbivores utilize heterogeneous grasslands unevenly which can create a pattern of degraded areas interspersed between under-utilized areas. Although this patchiness can be beneficial for biodiversity, it can also negatively impact production objectives. This study examines how livestock behavior management can maintain biodiversity while improving pasture utilization and therefore production. The authors suggest livestock have cognitive abilities to solve spatial tasks involving tradeoffs between travel costs and forage quality and quantity. The study concludes by listing management strategies to modify grazing distribution by providing water, supplement, salt, shade and shelter. 63) Rotational Grazing on Rangelands: Reconciliation of Perception and Experimental Evidence. Briske, D.D., Derner, J.D., Brown, J.R., Fuhlendorf, S.D., Teague, W.R., Havstad, K.M., Gillen, R.L., Ash, A.J., Willms, W.D. 2008. Rangeland Ecology & Management 61(1):3-17. Summary: This study conducts a literature review comparing ecological flora and fauna responses in pastures under two types of management: 1) continuous grazing, and 2) rotational grazing. Despite the allegiance for managed intensive rotational grazing (MIRG) as being

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ecologically and productively superior, the result of this synthesis fails to support this assumption. The authors suggest landscape attributes (e.g. slope, aspect, soils, sun-shade ratios) impose hierarchal constraints over grazing pressure and flora-fauna response, and that simply moving the herd in a consistent temporal management regime only establishes the control treatment in managed grazing. The authors conclude that knowledge of landscape feedbacks allows managers to consider other grazing strategies, that along with MIRG, can enhance and pasture production.

64) Burning and Grazing to Promote Persistence of Warm-Season Grasses Sown into a Cool-Season Pasture Bouressa, E.L., Doll, J.E., Cates, R.L. Jr., Jackson, R.D. 2010. Ecological Rest. vol. 28 no. 1 40- 45 Summary: This experiment attempts to establish C-4 warm season grasses into an existing pasture dominated by cool season C-3 grasses in Wisconsin. Cool season species provide adequate forage during spring and fall periods, but fail to provide adequate forage during the hot dry summer months; therefore, establishing warm season grasses in C-3 dominated pastures should increase over-all annual production. The researchers seed warm season grasses into existing C-3 turf, and then defer grazing to allow C-4 grasses to establish. The plots were then subjected to grazing and burning treatments. Results indicate burning increased C-4 grass and rotational grazing had minimal impact on C-4 recruitment. The authors’ conclude the addition of the warm season species into existing cool season pasture is possible through grazing deferment during the establishment period and by using fire to stimulate C-4 growth.

65) Grazing Management and Microclimate Effects on Cattle Distribution Relative to a Cool Season Pasture Stream. Haan, M.M., Russell, J.R., Davis, J.D., Morrical, D.G. 2010. Rangeland Ecology & Management 63(5):572-580. Summary: This paper examines the relationship between pasture microclimates as measured by heat indexes and livestock utilization of streams for cooling. The researchers seek ways to minimize livestock use of cold water streams during warm periods. Results indicate a positive correlation between higher heat indexes and livestock utilization of streams. Pastures with cool areas, such as pools of shade, display less livestock stream utilization. Pastures with off-stream watering systems show no difference between heat and stream use. Pastures with steam restrictions show less stream utilization. The authors conclude that providing shade and stream restrictions are the best ways to keep livestock out of streams.

66) Persistence of Native C4 Grasses under High-Intensity, Short-Duration Summer Bison Grazing in the Eastern Tallgrass Prairie Jackson, R.D., Paine, L.K., Woodis, J.E. 2010. Restoration Ecology, Vol. 18, Issue 1, pages 65– 73. Summary: This paper examines the persistence of warm season C-4 grasses to grazing by bison in Southern Wisconsin. The authors tested 5 warm season C-4 species both in and in mixed units. The warm season grasses were allowed 2 seasons to establish. Bison were rotated through test plots 2-3 times each season for 8 years. Results show a decrease in cover by all 5 warm season species. Likewise, cool season C-3 grass species re-established their presence in all units. By the eighth season, warm season grasses remained the dominant cover with cool

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season species filling the interstitial spaces. The authors conclude that establishing warm seasons species in pastures dominated by cool season species increases functional diversity and productivity.

67) Ecosystem Management Based on Natural Disturbances: Hierarchical Context and Non-Equilibrium Paradigm Mori, A. S. (2011). Journal of Applied Ecology, 48(2), 280-292. Summary: This paper discusses the importance of “Disturbance Theory” in designing management strategies to increase ecosystem function. Although this review is not specific to pasture management, the associated general principles of disturbance ecology are discussed in ways to elucidate novel concepts that may increase pasture resilience and the associated benefits of maximizing diversity and sustainable production. The author concludes that restoration of ecosystem function matters, and that restoring degraded grassland-savanna systems is accomplished through restoration of keystone processes, such as fire and grazing.

68) Sustainable, Low-input, Warm-season, Grass-legume Grassland Mixtures: Mission (Nearly) Impossible? Muir, J. P., Pitman, W. D., & Foster, J. L. (2011). Grass and Forage Science, 66(3), 301-315. Summary: Ecological diversity and the associated resilience of North America pastures have declined under the current management paradigm that seeks to maximize production through species-poor forage mixtures based on a few species of grass and legumes. Promoting low diversity monocultures to achieve optimal sustained harvest defies ecological wisdom, whereby species poor systems lack resilience and are therefore vulnerable to rapid transitions from functional to dysfunctional ecosystems. This paper calls upon grazing research to consider maximizing pasture production and sustainability through increasing pasture plant diversity. The authors investigate the potential of a few native legumes to increase pasture production. Results indicate higher pasture production can be achieved by increasing species diversity. The authors suggest more research into which native species should be included in pasture seed mixes needs to occur. concludes this is the direction we need to move. For example, the upper Midwest, USA has approximately 250 species of grasses and 250 species of forbs, many of which should contribute to forage quality, are adapted to the indigenous climate and soils, and have fed herbivorous animals for millions of years.

69) Vegetation Response to Cattle Grazing in the Ethiopian Highlands. Mwendera, E.J., Saleem, M.A.M., Woldu, Z. 1997. Agriculture, Ecosystems & Environment 64(1):43-51. Summary: This paper examines the impacts of different grazing intensities on vegetation in the Ethiopian highlands. Treatments include light, moderate, heavy, and very heavy grazing intensities. Un-grazed plots act as a control. Results indicate heavy and very heavy grazing significantly reduces above ground biomass, and very heavy grazing changes plant species composition, and the community is increasingly dominated by unpalatable species. Species richness increased in all treatments when compared with the un-grazed treatment. Grazing during the dry period had a negative impact on productivity. The authors conclude stocking rate indexes need to consider seasonal climate patterns such as precipitation for good pasture management.

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70) The New-Forest, England - a Threatened Landscape of Global Significance Nelson, J. G. (1995). Natural Areas Journal, 15(2), 168-174. Summary: The of Southeastern England was established in tenth century and is today considered is a prominent natural and . The scenic qualities of New Forest have evolved over many centuries through a set of interactions between vegetation, animals, and a variety of human activities such as silviopasture, grazing and hunting. Grazing is considered to have a strong influence in maintaining a variety of communities including heath, grassland, and deciduous which in turn maintains a high level of biodiversity. Increases in tourism threaten to change existing management including reductions in grazing. The author is concerned loss of grazing will tragically alter the flora-fauna communities and reduce biodiversity. The author suggests new management plans should consider England’s New Forest as a United Nations ''World Heritage Site''. This designation would encourage management strategies similar to those practiced over millennia, which have helped New Forest achieve international recognition.

71) Pasture Growth, Production, and Quality under Rotational and Continuous Grazing Management Paine, L. K., Undersander, D., Casler, M. D. (1999). Journal of Production Agriculture, 12(4), 569-577. Summary: Management intensive rotational grazing (MIRG) is an established practice for livestock production in the Midwest, USA. MIRG is thought to increase pasture forage and production, yet despite this perception many livestock producers practice continuous (CON) grazing. The goal of this study is to examine forage production and quality between MIRG and CON grazing systems. Forage production and quality are monitored on 3 MIRG and 3 CON between 1994 and 1995. Results indicate forage production and quality for MIRG pastures was greater than CON pastures.

72) Restoration of Degraded Grazing Lands through Grazing Management: Can it Work? Papanastasis, V. P. (2009). Restoration Ecology, 17(4), 441-445. Summary: Over grazed land can become severely degraded. Restoration of degraded grazing lands often includes vegetation improvements such as reseeding, , reforestation, and grazing exclusion. These practices can be expensive and create additional ecological problems such as encroachment by late successional woody invasive species, undesirable species, exotic species, and unpalatable species. Management practices that encourage reforestation and grazing exclusion often facilitate “afforestation”, a process in which functional grasslands rapidly transition into dysfunctional woodlands. The author suggests many degraded pastures can be restored by a variety of practices including: reseeding, tree planting, and appropriate grazing management. The author concludes restoration of degraded pastures should never seek long- term grazing exclusion as a viable management strategy.

73) Abandonment in Grazing Systems: Consequences for Vegetation and Soil Peco, B., Sanchez, A., Azcarate, F. (2006). Agriculture Ecosystems & Environment, 113(1-4), 284-294. Summary: Ancient anthropomorphic Spanish savannas, or dehesa zones, are suffering from abandonment of traditional farming practices, including grazing. This study examines the impacts of abandonment on vegetation composition, richness and heterogeneity and also

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differences in soil and light resources. Results show ungrazed systems display less clay, organic matter, total nitrogen, and available water than grazed systems. Abandonment also reduces light availability in mesic and wet mesic sites. Species richness between grazed and ungrazed treatments did not differ significantly, but floristic composition between the two treatments changed dramatically, trending towards lower quality unpalatable species in ungrazed systems. Agri-environmental policy for Mediterranean grasslands needs to consider the negative ecological impacts associated with grazing abandonment. Policy should seek to promote the diversification of grazing systems to maximize species diversity and ecosystem services associated with low-density grazing (LDG) in this region.

74) Twenty-Five Years of Paradox in Plant-Herbivore Interactions and "Sustainable" Grazing Management Provenza, F. D. (2003). Rangelands, 25(6), 4-15. Summary: The author describes the failures of continuous, moderate, and managed rotational grazing systems in semi-arid rangelands (e.g. west of the 100th meridian North America). The article suggests these failures can be ironically contributed by our focus to optimize production of key forage species in order to optimize animal rate gains. The failures are exacerbated by our utilization of singular herbivore species and rates of production that impede herbivore and culture. This type of management disallows our ability to comprehend complexities between plants and herbivores. The author concludes the best way to prevent the demise of rangeland isn’t through better technologies, but instead through developing better grazing cultures that include plants, animals and markets.

75) Impact of Pruning Eastern Red Cedar (Juniperus virginiana) Schmidt, T. L., & Wardle, T. D. (2002). Western Journal of Applied Forestry, 17(4), 189-193. Summary: Eastern red cedar (Juniperus virginiana) is often considered invasive in abandon landscapes and pastures. Typically, management for Eastern red cedar involves complete removal and elimination; practices which can impose excessive labor and associated costs. This paper suggests that instead of “total elimination”, managers should focus on control methods that enhance pasture production while reducing labor and costs. Control methods include pruning cedars to mimic fire-singe and browse lines at heights of 2-3 meters. This procedure enables enough sunlight to sustain intercanopy ground-layer vegetation. This type of management, control verse elimination, creates heterogeneous habitats for a variety of plant and animal species. Another benefit to this type of management is the creation of shade-pools for livestock and wildlife to escape excessive heat-stress. Finally, properly pruned red cedar can decrease wildfire threat and promote a lumber industry based on value-added-products.

Policy, Programs and Research Needs

76) The Cost of Policy Simplification in Conservation Incentive Programs Armsworth, P. R., Acs, S., Dallimer, M., Gaston, K. J., Hanley, N., Wilson, P. (2012). Ecology Letters, 15(5) Summary: This paper examines the effectiveness of simple incentive payments to farmers, such as the Conservation Reserve Program (CRP) to conserve biodiversity and enhance ecosystem services. The term “simple” refers to “a one-program to achieve all conservation objectives”

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instead of a variety of programs targeted for specific conservation objectives. The authors argue the sheer variety of conservation objectives demanded by the public tax dollar, including soil stabilization, increases in flora-fauna diversity, water infiltration, and carbon sequestration to name a few, can come nowhere close to being met by a simple program. The paper points out simplified programs are currently justified as a means to decrease administrative burden for designing and implementing more holistic management strategies. The author’s findings show policy simplifications result in a 50–100% loss in achieving environmental objectives, depending on the conservation target. The authors suggest that even though administration costs to design and implement more holistic agri-environment schemes might increase by 70%, additional costs for more complex policies are worth bearing.

77) Categorization of Grazing Systems to the Development of Land Use Policy in Aragon, Spain Barrantes, O., Ferrer, C., Reine, R., Broca, A. (2009). Grass and Forage Science, 64(1), 26-41. Summary: Low-input large-scale grazing systems constitute a substantial part of what is termed “High Nature Value” farmland in Europe. Despite the social-ecological advantages associated with grazing pastures, no government program exists to encourage this type of agriculture. Lack of incentive programs are partially due to the variety of grazing practices, including: grazing strategies such as low density continuous and high to moderate density intensive managed rotational, livestock variety including cattle, cows, , swine, and sheep, and product variety including dairy, , and fiber. This variety makes it difficult to design a simple incentive program suitable to all grazing types. The authors then develop categories (typologies) of livestock systems within their ecoregion to help inform policy formation. The authors conclude grazing advocates need to categorize regional grazing typologies to inform regional policy formation.

78) Southern European Grazing Lands: Production, Environmental and Landscape Management Aspects. Hadjigeorgiou, I., Osoro, K., Fragoso de Almeida, J.P., Molle, G. 2005. Livestock Production Science 96(1):51-59. Summary: The authors of this paper champion grazing as a sustainable form of food production and suggest the E.U. should focus upon creating policy and programs to encourage grazing over confinement livestock husbandry. Pro-grazing arguments are framed from a socio-ecological perspective. Challenges to grazing expansion in southern Europe are identified. The paramount challenge to grazing expansion is the inability for current confinement systems to switch to low input grazing systems. Confinement based systems list three primary reasons for their inability to switch over to low-input grazing operations, including: 1) the relentless debt burden associated with high-input confinement livestock husbandry, 2) perceptions of lower gross production associated with low-input grazing systems, and 3) lack of government policy to ease the transition.

79) Green futures for grassland: A regional case study on engagement to develop measures for improving environmental benefits on intensively managed grassland Hopkins, A., Lobley, M. (2007). In Vliegher A. d., Carlier L. (Eds.), Proceedings of the 14th Symposium of the European Grassland Federation, Ghent, Belgium, 3-5 September 2007.

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Summary: The goal of this project is to engage livestock farmers, environmentalists, processors, and consumers to find solutions that sustain agricultural production while improving ecosystem function and service. Through regional meetings, farmers identify management changes and financial implications as barriers to switching from confinement high-input based livestock production to grazing low-input based livestock production. Also, many current confinement based farmers lack the knowledge necessary to design, construct, and manage successful grazing operations. Likewise, processors and consumers lack information necessary to capitalize on emerging markets and benefits associated with pasture based agriculture. Meeting participants identified the need for local demonstration sites as important for the near- term expansion of grazing in Europe.

80) China's Grassland Contract Policy and its Impacts on Herder Ability to Benefit in Inner Mongolia: Tragic feedbacks Li, W., & Huntsinger, L. (2011). Ecology and Society, 16(2), 1. Summary: Ecological integrity and associated livestock production from Northern China grasslands has declined since the 1980s. The declines are associated with the implementation of the "grassland contracting policy" which re-allocated former grazing common-lands into quasi- private herder units. This paper examines the relationship between policy implementation and the declines in ecosystem integrity and grassland production in Northern China. The authors conclude the individual ownership policy in Northern China semi-arid regions has eroded local knowledge and associated social-ecological resilience. The quasi-private herder units place inflexible boundaries that prevent herders from adjusting to non-equilibrium conditions (e.g. extreme weather events) by removing the flexibility of “otor” or herd movement. The result of this inflexibility sets in motion a series of feedbacks which cause declines in pasture health, ecological integrity, and farmer-community prosperity. In conclusion, sectionalism in semi-arid regions disrupts biotic landscape patterns causing rapid and permanent declines in ecological integrity.

81) Management of Grasslands in Intensive Dairy Livestock Farming. Kristensen, T., Soegaard, K., Kristensen, I.S. 2005. Animal Production Science 96(1):61-73. Summary: Recent policy change in the E.U. potentially makes grass-based livestock production competitive with confinement based livestock production. This paper reviews different pasture production systems to extrapolate ideas on how to maximize dairy output. The question this paper proposes to answer concerns the ability for pasture based agriculture to supply the current E.U. dairy demand. The authors identify research needs that include: production of pasture and forage crops, the role of supplemental feeds, seasonal effects, livestock behavior, and the role of modern technology in pasturing. The paper concludes the lack of grazing knowledge makes it difficult to assess pasture based agriculture’s potential to meet E.U. demands.

82) Societal Expectations of Livestock Farming in Relation to Environmental Effects in Europe Milne, J. A. (2005). Livestock Production Science, 96(1), 3-9. Summary: The intensification of confined animal feeding operations (CAFOs) leads to adverse impacts in air and water quality. European countries regulate these impacts through a variety of mechanisms, which are viewed favorably by the public. Further reductions in adverse environmental impacts require additional regulation. Despite the publics’ acceptance of current regulation, the author suggests consumers are more motivated for additional regulation through

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their perception of human food quality and animal welfare instead of adverse effects on air and water quality, and these attitudes will likely to prevail into the next decade.

83) Low-intensity Livestock Systems in Europe: An Opportunity for Quality Products, Recreation Revenues and Environmental Conservation Sebastia, M. T., Canals, R. M., Marks, E., Llurba, R. (2008). In Hopkins A., Gustafsson T., Bertilsson J., Dalin G., Nilsdotter-Linde N. and Sporndly E. (Eds.). Conference proceedings: 22nd General Meeting of the European Grassland Federation, Uppsala, Sweden, 9-12 June 2008" Summary: This paper examines the role of low-intensity livestock operations as an innovative management procedure for future change scenarios. The authors suggest low-intensity livestock systems preserve biodiversity, provide ecosystem services, and offer an income source for marginal agricultural areas and for value added producers. Also, low-input requirements associated with low-intensity grazing can economically out-perform high intensity agriculture. The authors conclude low intensity livestock operations offer a resilient means to off-set future uncertainties associated with climate change and energy resources.

84) Barriers to the Adoption of Management-intensive Grazing Among Dairy Farmers in the Northeastern United States Winsten, J. R., Richardson, A., Kerchner, C. D., Lichau, A., Hyman, J. M. (2011). Renewable Agriculture and Food Systems, 26(2), 104-113. Summary: The authors use survey results from a 1000 dairy producers in northeastern US to determine perceived barriers to the adoption of management-intensive grazing (MIG). Survey results indicate 13% of respondents utilize MIG to feed their herd, while 47% use some form of pasture, and 40% are completely confinement based. Respondents report the lack of information and technical assistance is a minor barrier to adoption of MIG. More importantly, confinement based producers with higher debt ratios view the financially related barriers as significant obstacles.

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