Why are we thinking about grazing at Brimham Rocks?
Grazing will improve the habitat on Brimham Moor, especially because the cattle will:
1. Browse off the young birch saplings and the coarser grasses
This will create a varied age structure throughout the heather, grass and scrub mosaic. It will also prevent scrub from maturing to woodland and shading/drying out the heathland vegetation, turning it into grassland. It will also maintain a varied age structure of scrub to provide cover for our bird species.
With the cattle impacting on the saplings we can reduce the use of petrol driven machinery, the use of herbicides on site and the damage to the soil through use of heavy machinery.
2. Maintain a varied structure of heather to improve the habitat for ground nesting birds
Studies show (Natural England, 2013) that meadow pipits favour intermediate heather cover mixed with grasses and skylark densities are highest on short grass moorland. Grouse and stonechat are affected by a loss of heather cover. When we introduce grazing at Brimham birch incursion will be kept under control and loss of heather cover will be stopped. We must try and create as many niches as possible. The random and wide raging nature of cattle grazing is best suited to this job. Species which require areas of short, open and diverse vegetation, notably curlew and other waders, will also benefit from cattle grazing to provide the habitat they require. These species are less common at Brimham but we are keen to encourage them to safeguard their numbers. It is well known that wader numbers are struggling and if we can provide them breeding grounds free from large scale disturbance we hope we might be able to help conserve their numbers.
3. Prevent the further growth of large trees which dry out the moor
A wet moor is of more benefit to carbon sequestration than a dry one. Bog forming plants, namely the sphagnum mosses require continuously wet conditions to grow, as they do they lock away carbon, the peat must stay wet and unexposed to the atmosphere to help keep the carbon locked away. Brimham is not 100% covered in bog or peat soils, but we must protect what we have, and increase the site’s potential to support the ground level of the moor. There is strong evidence that water tables are shallower (i.e. closer to the surface) on grazed sites and this is attributed to reduced vegetation development (Natural England, 2013). Also, if we increase our site’s capacity to hold water, it will be of more benefit to the surrounding land by holding water back on top of the hill and releasing it slowly into watercourses, rather than it all rushing straight off.
4. Introduce droppings and poach the ground to diversify the habitat for invertebrates
This will provide more food for birds and small mammals. There is strong evidence (Natural England) that uniformly tall swards (grassy turfs) and ungrazed swards limits the availability of invertebrate prey to moorland birds such as the meadow pipit, and the removal of vegetation through grazing increases invertebrate abundance.
5. Improve soil quality by increasing bacteria and fungi content
It is suggested that low to intermediate level grazing adds to the levels of microbial biomass in the soil, so improving the health of the soils and the nutrient cycling within the habitat, but not too much that fungal decomposition is suppressed. Healthy soils are important globally as soils contain three times the carbon that vegetation does, and twice that in the atmosphere (Natural England, 2012).