Sheep grazing significantly influences landscapes across the globe, acting as both a vital resource and a driver of ecological change. The environmental impact of this practice is complex, presenting both benefits and risks. Understanding these interactions is essential for creating sustainable land management strategies that balance agricultural productivity with ecological well-being.
The Two Sides of Sheep Grazing
The environmental consequences of sheep grazing are highly dependent on factors like grazing intensity, ecosystem type, and management practices. Overgrazing, often resulting from high stocking densities, can cause soil erosion, biodiversity loss, and grassland degradation. Fragile environments, such as the mountainous regions of the North Atlantic, are particularly vulnerable due to thin soils and slow biological processes. Research in Iceland highlights widespread erosion linked to intensive grazing, especially in volcanically active areas (PURE Faroe Islands).
Soil Erosion
In the North Atlantic region, high sheep densities can significantly impact ecosystem structure and function. Mountainous areas, with steep slopes and thin soils, are particularly susceptible to the impacts of overgrazing. Erosion has been linked to high-intensity sheep grazing in places like the Faroe Islands, Greenland and Iceland. The slow biological processes in these regions make recovery from grazing-induced degradation a long and arduous process. In Iceland, for example, erosion affects a significant portion of the land, with recovery proving especially slow in volcanically active zones (PMC).
The Benefits of Strategic Grazing
Sustainably managed sheep grazing, however, can offer substantial environmental benefits. Strategic grazing can be a valuable tool for habitat management, enhancing biodiversity, and even assisting in pest control. Integrating sheep into arable farming systems also provides numerous advantages. Sheep manure naturally fertilises the soil, enriching it with organic matter, and lessens the need for synthetic fertilisers, which carry significant environmental risks (Agricology). Sheep also effectively control weeds, reducing herbicide use and minimising soil and water contamination risks.
Sheep and Plant Life
Sheep’s dietary preferences significantly influence plant community composition. They tend to favour graminoids (grasses, sedges, and rushes – grass-like plants) over dwarf shrubs, which can alter vegetation structure over time (Rangelands Gateway). This selective grazing can be advantageous in specific situations, such as controlling invasive species like common ragwort.
Controlling Invasive Plants
A study in Northern Germany showed that sheep can effectively reduce ragwort populations, encouraging the growth of other herb species and promoting a more diverse vegetation structure (MDPI). Sheep displayed a preference for ragwort with higher sugar content, leading to a significant decrease in its proportion in the pasture over two grazing seasons. This demonstrates the potential of using sheep as a natural method of controlling unwanted plant species.
Impact on Biodiversity
The relationship between sheep grazing and biodiversity is multifaceted. While intense grazing can reduce plant diversity, leading to dominance by grazing-tolerant species, moderate grazing can sometimes enhance it. By creating varied habitats and food sources, well-managed sheep grazing can support a range of insects, pollinators, small mammals, and farmland birds. For example, in diverse swards, the presence of leguminous species (plants that fix nitrogen) naturally enriches the soil, reducing reliance on synthetic nitrogen fertilisers (Agricology).
Long-Term Effects
However, research in the British uplands indicates that the negative impacts of sheep grazing on plant biodiversity can persist for decades, even after the removal of sheep (University of Liverpool). This long-term study, comparing grazed and ungrazed plots, found that vegetation in ungrazed areas had significantly higher nutritional quality and decomposed faster, highlighting the profound and lasting impact of sheep on these ecosystems. The recovery of key plant species can take up to 60 years, emphasizing the need for long-term restoration efforts.
Effects on Grasslands
In lowland Britain, the effect of sheep grazing on unimproved neutral grasslands, like the valuable MG5 ‘old meadow’ pasture, is subject to ongoing debate. While moderate grazing is generally considered beneficial, concerns exist that high-intensity sheep grazing may reduce forb diversity (herbaceous flowering plants other than grasses) compared to cattle grazing. A systematic review has emphasized the importance of managing grazing intensity, which is often a more crucial factor than the type of livestock (Environmental Evidence). The review suggests that moderate grazing levels are generally most beneficial for plant species conservation. However, the data directly comparing sheep and cattle grazing on MG5 pasture is limited, making it difficult to draw definitive conclusions.
Greenhouse Gases and Carbon
Beyond the direct impact on vegetation, sheep grazing also contributes to broader environmental concerns, such as greenhouse gas emissions. Livestock farming, including sheep, is a significant contributor to global greenhouse gas emissions. As ruminant animals, sheep produce methane during digestion, and manure management practices further add to these emissions (Our World in Data).
The Potential for Carbon Storage
However, sustainable grazing systems can play a role in carbon sequestration. Healthy grazing lands have the potential to act as carbon sinks, absorbing atmospheric carbon dioxide and storing it in the soil and vegetation. Regenerative grazing, a practice where livestock are moved between different pastures or ‘paddocks’, allows vegetation to recover between grazing periods. This prevents overgrazing, promotes plant diversity, and can improve soil health, enhancing its capacity to store carbon. Research by NEIKER in the Basque Country demonstrated a 4% increase in soil carbon sequestration under regenerative grazing compared to conventional methods, along with a 30% increase in grass production (Neiker).
Sheep in Sustainable Systems
Integrating sheep grazing into agro-ecological systems offers further environmental benefits. In minimum-till rotational cropping systems, sheep can reduce or replace the need for herbicides and mechanical tillage, minimising reliance on fossil fuels (National Agricultural Library). Research is also exploring the innovative combination of sheep grazing with solar arrays, investigating its potential to improve soil health, pollinator habitat, and vegetation biodiversity (Cornell University). This ‘solar grazing’ approach could offer a dual benefit: generating renewable energy and promoting sustainable land management.
A Case Study: The CAFRE Hill Farm
The CAFRE hill farm in Glenwherry, Co Antrim, provides a practical example of sustainable sheep farming in a hill environment. This 960-hectare farm demonstrates how sheep can be managed to enhance and protect diverse habitats within marginal farmland (Farmers Journal). The farm strategically uses different sheep breeds for specific purposes: pure Blackface ewes graze rough moorland and heather, contributing to the management of these habitats, while crossbred ewes maintain lower hill slopes, preventing the dominance of coarser vegetation and fostering a diverse grassland environment.
Integrating Conservation and Farming
The CAFRE farm actively integrates conservation practices with sheep farming. A significant area of 60 hectares, previously afforested with conifers, is being restored to blanket bog through re-wetting. Sheep grazing plays a role in maintaining the open nature of these bogs by preventing scrub and tree encroachment. Furthermore, 40 hectares of the farm are designated as a breeding site for waders and curlew. Sustainable grazing regimes in these areas are designed to minimise disturbance to nesting birds and maintain suitable habitat structure, demonstrating how farming and conservation can coexist effectively.
Sustainable Practices
Minimising negative impacts and maximising the benefits of sheep grazing hinges on sustainable management practices. This involves carefully controlling stocking rates, implementing rotational grazing systems, and considering the specific ecological context of the grazed area. The CAFRE farm exemplifies how sheep grazing can be integrated into landscape management to minimise harm and enhance environmental values (Farmers Journal).
A Holistic Approach
Achieving truly sustainable sheep grazing requires a holistic approach. This means considering ecological, economic, and social factors in decision-making. It necessitates a shift from a purely production-focused perspective to one that prioritises biodiversity, ecosystem services, and long-term landscape health. For instance, farmers need to consider the carrying capacity of their land, the nutritional needs of their sheep, and the potential impacts on local wildlife, all while maintaining a viable business. This may involve re-evaluating traditional practices, exploring alternative strategies such as mixed grazing (combining sheep with other livestock like cattle), and embracing innovative approaches like regenerative grazing. Even using sheep for ‘lawn mowing’ in urban areas is being explored, highlighting the versatile role these animals can play (UC Davis).
Economic Considerations
The economic viability of sustainable sheep grazing is also a crucial factor. While implementing sustainable practices may involve initial costs, such as fencing for rotational grazing or investing in different breeds, there can be long-term economic benefits. Improved soil health can lead to increased pasture productivity, reducing the need for supplementary feed. Furthermore, there is a growing market demand for sustainably produced lamb, which can command premium prices. Governments and organisations may also offer incentives or subsidies to support farmers adopting sustainable grazing practices.
Looking to the Future
The environmental impact of sheep grazing is a complex issue with both potential benefits and risks. While overgrazing can undoubtedly cause environmental damage, well-managed sheep grazing can be a valuable tool for habitat management, biodiversity conservation, and even climate change mitigation. The future of sheep farming and its impact on landscapes depends on adopting sustainable practices, prioritising ecosystem health, and acknowledging the interconnectedness of agriculture and the environment. Key recommendations include carefully controlling stocking densities, implementing rotational grazing systems tailored to the specific environment, continuous monitoring of vegetation and soil health to adapt management practices, and exploring innovative approaches like integrating sheep with renewable energy infrastructure. By embracing a holistic and adaptive approach, sheep grazing can contribute to a more sustainable and resilient future for our landscapes.
