How to Rewild

Inland Rock

Habitat Management Plan

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Inland Rock
Habitat Guide

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One of the least-studied British habitats, Inland Rock is, like Bog, home to a specialist community which thrive in these nutrient-poor habitats. This category takes in a range of seral ecosystems – over time they are colonised by plants. The way this happens depends on the habitat – we have both vertical and horizontal rock faces represented here.

Vertical faces – inland cliffs – degrade into smaller rocks, which fall into scree at the base of the slope. Horizontal faces – limestone pavements – were scraped clean by glaciers, but may succeed to scrub or woodland if there is low grazing pressure. Exposed rock habitats are also created by quarrying, and these may develop into similar ecosystems over time. One outlier here is Calaminarian Grassland, which forms atop toxic soils (rich in heavy metals from mining or natural processes) and occasionally on contaminated river sediment.

Sub Habitats

All inland cliffs and scree slopes formed by natural processes. Typically exposed rock with sparse vegetation cover.

Geological feature found in some areas of Northern England, Wales and Scotland. Exposed limestone rock with sparse vegetation cover, created by glacial scouring.

Unique community of plants found on soils which are rich in heavy metals. Typically found in mining waste deposits and sites contaminated by this waste, but also, rarely, from natural processes.

Typically non-natural rock formations, including quarries and other mining sites.

Value

The primary value of these habitats is in their unique plant, lichen and bryophyte (moss and liverwort) communities, though there are invertebrates and birds which can be found here, too. Inland Rock Outcrop and Scree Habitats include some of the UK’s wildest ecosystems, with very little human influence, and a relatively natural level of grazing pressure in some places. With such low value for resource extraction or agriculture due to the inaccessibility and hazardous rock face, these habitats have often benefited from benign neglect.

In contrast, Limestone Pavement tends to occur in areas with high levels of disturbance from tourism and grazing. Without these factors, the habitat has high potential for biodiversity, with lush communities of plants growing in the crevices, and a nutrient-poor sparse scrub habitat developing in well-managed areas.

Calaminarian Grassland is an odd habitat, typically found on spoil heaps of waste from mines. Here, the heavy metal-rich substrate acts like a nutrient-poor soil, resisting plant growth and resulting in a unique plant community which can also be found in certain scarce wild places with the same characteristics.

Other Inland Rock and Scree covers mining and quarrying operations, which could over time succeed to one of the habitats above, but at this stage have low vegetation cover. These habitats currently have low value for biodiversity, but in the case of disused sites they may already provide nesting opportunities for birds (Raven, Peregrine Falcon), and are likely to be of higher value in the future.

Goats on cliffside
A balanced population of goats can maintain a healthy inland rock ecosystem, but these animals can easily get out of control.

Protect

Horizontal and vertical rock faces suffer from two major threats – overtourism and overgrazing…

Overtourism includes climbing of vertical surfaces and use of horizontal surfaces for hiking and as secure locations for climbing anchors. The impact of climbers ‘gardening’ ledges to keep them clear of soil and vegetation is a reduction in biodiversity and a pause in successional processes in these locations. Some plants, like Dark-red Helleborine, are uniquely adapted to rocky ledges, and as pioneer species, they aid in the colonisation of these exposed outcrops, boosting their biodiversity value. Fencing-off sensitive habitats and creating informative signage that helps tourists understand the value of these rare species can aid in their protection.

Overgrazing (and undergrazing) can lead to a decline in the habitat quality of horizontal rock faces – i.e. Limestone Pavements. While this can also be an issue in scree and vertical habitats, the inaccessibility means that only nimble livestock like goats would pose a significant issue. When pavements are overgrazed, the lush vegetation typical of crevices in the rock is lost, and a sparse scrubland is not permitted to develop. However, low browsing pressure can lead to the succession of woodland habitat over time, and the loss of specialist rock-dwelling plant communities.

Calaminarian Grasslands are a unique habitat which also have some complications – with heavy metals present in the soil, and many sites in riparian (river edge) locations, there is an ongoing debate as to whether we should treat the toxic soils or conserve the habitat. If the habitat is to be protected, then sheep are the best livestock to graze here, as heavy metals are still bioavailable in their dung, unlike with cattle, which tend to ‘graze off’ the contaminants over time. If the area is grazed with sheep, the existing low sward can be maintained. But this habitat is seral in nature – it would naturally shift over time and be colonised by birch and gorse scrub.

Other Inland Rock and Scree sites have huge potential for future biodiversity if restored correctly, but even during productive operation, protection can help to ‘set up’ the habitat for the future. Experts recommend that certain quarry areas are set aside as protected zones, allowing for the colonisation of Inland Rock species – these can be introduced as seed from the local area or in soil from other mining sites (beware of invasive species). Alternatively, rotating mining operations across the site can allow pioneer species to take hold.

Where possible, non-native Buddleia should be controlled in Inland Rock habitats as it is highly invasive in these ecosystems. Flowerheads can be cut off in Autumn as seeds won’t set until the following year.

Polypody Fern on Scree Slope
Succession tends to happen very slowly on upper scree slopes, where the constant action of moving rock will keep plant growth under control.

Restore

In some cases, restoration of Inland Rock habitats is not necessary as these habitats are effectively self-managing. Remove any invasive species and bringing grazing pressure to a normal level will allow the habitat to recover by itself – vertical rock faces and scree are self-renewing, as they continuously evolve when more rock falls. However, other habitats here, like Calaminarian Grassland and Limestone Pavement, will gradually shift towards woodland due to succession. Whether or not to intervene in these processes depends on your philosophy of land management. Our recommendations below are based on what would naturally have occurred, in the absence of human disturbance and the presence of a healthy wild guild of herbivores.

With even relatively low levels of grazing pressure, as might be expected in a wild upland ecosystem, Limestone Pavement will remain exposed, or form a sparse scrubby ecosystem. In fact, our evidence for this comes from the present day existence of these relict habitats, which have survived intact since the last Ice Age. This makes maintaining a low level grazing presence seem like a logical management practice which ‘leans in’ to wild processes, working with, rather than against nature.

In contrast, Calaminarian Grasslands appear to succeed to scrub and then woodland over time in the absence of sheep. Given that sheep are not naturally present in the British Isles, and that the wild herbivores which would likely have been found here (bovids) lock up the heavy metals in their dung, then maintaining this habitat feels more like working against the force of nature than working with wild processes. Some of the methods used for restoration of these habitats appear to underline this… While it is possible to restore a ‘degraded’ Calaminarian Grassland, this involves stripping off woodland soil and felling trees, reversing the process of succession. We can maintain this habitat in good condition, and this may be desirable to preserve rare plants, but restoration is of questionable merit, given that it typically exposes toxic soil to the elements.

Restoration of quarry and mining sites post-operations tends to differ depending on the water table. Sites with a high water table are likely to be flooded, and this can, as is the case at Cotswolds Water Park, create a high value ecosystem, rich in biodiversity. However, sites which are above the water table may still be of value to nature, and interventions can improve the speed and quality of succession.

In high water table sites, rather than leaving the landscape to ‘rewild itself’, it is better to strategically plant native species which will develop into self-sustaining ecosystems. This active approach was taken at Cotswolds Water Park, with a diverse riparian community of trees planted which now protects the site from wind exposure and creates both structural diversity and biodiversity. At Attenborough Nature Reserve, supplementary planting of floating reedbeds and marginal vegetation enhanced the biodiversity of deepwater habitats. In low water table sites, strategic relocation of soils and seed from similar, high quality habitat elsewhere can help to establish threatened plant communities on exposed rock and gravel substrates.

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