1. Identification and Creation of Optimum Habitat Conditions for Livestock.
Bailey, D.W. 2005. Rangeland Ecology and Management 58(2):109-118.
Optimum Habitat Condition (OHC) is a concept used by wildlife managers to maximize target populations (e.g. elk). The OHC model suggests animal performance is greater in heterogeneous landscape, especially at the lower end of carrying capacity. 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.
2. 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.
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.
3. 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.
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 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 ecosystem service and pasture production.
4. 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
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.
5. 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.
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.
6. 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.
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 monocultures 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 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.
7. Ecosystem Management Based on Natural Disturbances: Hierarchical Context and Non-Equilibrium Paradigm
Mori, A. S. (2011). Journal of Applied Ecology, 48(2), 280-292.
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.
8. 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.
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.
9. 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.
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.
10. The New-Forest, England – a Threatened Landscape of Global Significance
Nelson, J. G. (1995). Natural Areas Journal, 15(2), 168-174.
The New Forest of Southeastern England was established in tenth century and is today considered is a prominent natural and cultural landscape. 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 woodlands 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.
11. 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.
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 farms between 1994 and 1995. Results indicate forage production and quality for MIRG pastures was greater than CON pastures.
12. Restoration of Degraded Grazing Lands through Grazing Management: Can it Work?
Papanastasis, V. P. (2009). Restoration Ecology, 17(4), 441-445.
Over grazed land can become severely degraded. Restoration of degraded grazing lands often includes vegetation improvements such as reseeding, weed control, 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.
13. Abandonment in Grazing Systems: Consequences for Vegetation and Soil
Peco, B., Sanchez, A., Azcarate, F. (2006). Agriculture Ecosystems & Environment, 113(1-4), 284-294.
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 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.
14. Twenty-Five Years of Paradox in Plant-Herbivore Interactions and “Sustainable” Grazing Management
Provenza, F. D. (2003). Rangelands, 25(6), 4-15.
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 learning 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.
15. Impact of Pruning Eastern Red Cedar (Juniperus virginiana)
Schmidt, T. L., & Wardle, T. D. (2002). Western Journal of Applied Forestry, 17(4), 189-193.
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.