MANAGING COASTAL SOFT CLIFFS FOR INVERTEBRATES SUMMARY REPORT MAY 2007 FOREW0RD have a soft spot for soft cliffs. They form some of Introduction our country’s most scenic coasts and have a rare Coastal soft rock cliffs and slopes are home to many I quality of being wild and natural. For thousands rare insects, spiders and other invertebrates. This of years these cliffs have been actively shaped by the habitat is not just important for individual species, same processes of weathering, hydrology and sea soft cliff sites also support an incredible abundance erosion that are still active today. This is one of the and diversity of invertebrates. few habitats in the UK where pioneer communities of invertebrates have been able to survive without Soft cliffs have been rather neglected by naturalists disruption by man. and conservationists in the past, perhaps due to a lack of impressive sea bird colonies or because of It is perhaps nearly 60 years ago that I fi rst visited accessibility issues. Many nationally important sites Barton cliffs as a child, amazed that the seaside have been damaged or destroyed through coast could look so primeval. I was to become a geologist protection works or inappropriate management of in the Nature Conservancy, presenting at a public cliff tops. inquiry the case against the erection of coast protection on this geological Site of Special Scientifi c This summary of the Buglife report “Managing Interest of international importance: we won that Coastal Soft Cliffs for Invertebrates” describes the round. I then became responsible for invertebrates importance of coastal soft cliff sites for invertebrate in the re-named Nature Conservancy Council: some conservation in the UK, identifi es current and years later I went back to Barton cliffs to investigate future threats to soft cliff sites, and provides the insects and found that much of the cliffs had management guidance for protecting and been drained, terraced and defended from the enhancing the invertebrate faunas of soft cliff sea. We can never assume wild places and their sites. The full report provides further detail plus invertebrate fauna will remain natural. regional gazetteers and specifi c site management recommendations. It is intended to be an essential As both a geologist and an entomologist, the threats resource for coastal planners, conservation were all too obvious and the solutions had to be practitioners and land managers. more than just aiming for a natural look to the cliffs. In addition to the threat from coast protection, it has become clear that cliff top habitat quality, and restoration of cliff top herb-rich grasslands are a key factor in conserving soft cliff invertebrates. Naturalness of cliff and cliff top contribute to high , quality landscape for tourism, and an opportunity for people to appreciate coastal wildlife. son, The Art Agency We are very grateful to The Esmée Fairbairn Foundation for its grant to support our three year project. This report focuses on the resource and Cylindera germanica how to provide for its future. We believe it should be tle, an essential context document in coastal planning, water resource planning and in cliff top improvement for tourism, and sets a new basis for informing ff tiger bee conservation policy. , Cli Invertebrates, Artist: Ian Jack Soft Cliff Porth Neigwl on the Llyn Peninsula is the most important : site in Wales for soft cliff invertebrates. It is one of only two sites in the UK that support populations of the Alan Stubbs, Chairman, Buglife endangered mason bee Osmia xanthomelana. Cover: Eype, Dorset this page WHAT IS A SOFT ROCK CLIFF? SOFT CLIFFROCK CLIFFBIODIVERSITY BIODIVERSITY Coastal soft cliffs are cliffs in rocks that are poorly Where cliffs are colonised by plants, pioneer plant resistant to the natural processes of erosion communities rich in wildflowers such as Colt’s The Glanville foot (Tussilago farfara), Common Bird’s-foot Trefoil Fritillary that shape our coasts. These cliffs are formed of butterfly (Lotus corniculatus) and Wild Carrot (Daucus carota) rocks that have little resistance to erosion such as Melitaea cinxia clays, friable sands, shales and glacial deposits, often dominate. These plant communities provide is confined to contrasting with much more resistant ‘hard’ rocks. valuable nectar and pollen sources for bees and areas of short The cliffs are subject to frequent slumps and land other insects. The plants are also the food plants of grassland on slips caused by erosion by the sea, erosion by the phytophagous insects (such as the weevil Baris analis) south-facing rain, storms, and groundwater percolating through and their predators, including many of the solitary soft cliff slopes the cliff. Soft cliffs erode more quickly than hard wasps that nest on soft cliffs. and chines on cliffs and often have shallower gradients which the Isle allow far greater colonisation of vegetation and Hydrological features such as freshwater seepages of Wight. development of a wider range of habitats. and reedbeds accommodate invertebrates with aquatic stages in their life cycle including water substrate compaction, and water availability. It is Unprotected soft rock cliffs are a scarce resource beetles, craneflies and soldierflies; and provide often not the presence of one habitat feature but in the UK and are concentrated in England and Black Ven in Dorset is one of the most extensive landslip food plants and refuge for insects with specific the juxtaposition of a range of micro-habitats that Wales, which are estimated to have lengths of 256 systems in Europe, it is also one of the UK’s most associations with aquatic plants. Seepages and makes a site so important for a particular species. km and 101 km respectively. Far shorter lengths important invertebrate sites. pools provide wet muds that are required by Invertebrate species often rely upon a range of of soft rock cliffs occur in Scotland and Northern Soft cliff biodiversity many species of bees and wasps for nest habitat features to complete their life-cycles, if one Ireland. The UK holds a significant proportion of construction, these include the mason bee Osmia piece of this set of requirements is missing then a xanthomelana and Black-headed mason wasp site is not suitable for the species. For example, the habitat in north-western Europe. Some of the Coastal soft rock cliffs and slopes support rich Odynerus melanocephalus. burrowing bees require friable materials in which richest sites for invertebrates are the landslips invertebrate assemblages and are a refuge for to excavate nests, but also depend upon nectar along the coasts of Dorset and south Devon, the many rare species. In fact the main biodiversity On most soft cliff sites there are a range of these and pollen sources in close proximity. Sites which Isle of Wight, and the Gower and Llyn peninsulas in interest of soft cliffs is their invertebrate faunas. micro-habitats, plus others such as calcareous provide a range of micro-habitats on a small spatial Wales. These areas have considerable additional 29 invertebrate species are found only on soft rock interest in their geology, geomorphology and grassland and scrub. Habitat variation on a very scale are able to support a great range of species. cliffs in the UK, of these, 22 are Red Data Book small spatial scale can produce an incredibly scenery, exemplified by the recent designation of the species. Alongside those species restricted to soft complex environment in terms of temperature, The apparent concentration of invertebrate Dorset and East Devon Coast World Heritage Site. cliffs, there are at least another 75 invertebrates exposure, vegetation type and structure, stability, biodiversity at soft cliff localities can be partly We have identified many sites around the UK that have a strong affinity to the habitat. Well attributed to the loss of open habitats in the wider as being of national or international importance for represented groups are the Hymenoptera countryside through agricultural intensification. nature conservation. (bees and wasps), Coleoptera (beetles), Lepidoptera The Cliff tiger beetle The capacity of soft cliffs to offer a continuity of such (moths and butterflies), and Diptera (flies). Cylindera germanica habitats with such predictability is increasingly rare is only found on in the landscape and soft cliffs offer a refuge for The importance of coastal soft cliffs for the warm, south many once more widespread species. invertebrates hinges on their capacity to provide a facing soft cliffs historical continuity of micro-habitats rarely found of Dorset, Devon UK Biodiversity Action Plan and site with predictability elsewhere. Pioneer ecological and the Isle protection conditions and other micro-habitats provide ideal of Wight. The conditions for a range of species. The unstable adults are fast Coastal soft cliffs are a key component of the UK nature of soft cliffs and slopes constantly creates running predators and can be seen running over Biodiversity Action Plan (BAP) Priority Habitat bare ground and suppresses ecological succession. bare ground or sparsely vegetated areas. The larvae are found in burrows in damp sand. ‘Maritime Cliffs and Slopes’. The main biodiversity Whereas in other situations herb-rich pioneer importance of this habitat is often the invertebrate plant communities are ephemeral features – The ground fauna. A number of UKBAP Priority species are they naturally progress into closed grassland beetle Nebria dependent on the habitat, including the Cliff followed by scrub – the instability of soft cliff slopes livida is found at tiger beetle Cylindera germanica, the mining bee suppresses this change maintaining a continuity of the base Lasioglossum angusticeps, the Four-banded weevil early successional vegetation. of cliffs where it wasp Cerceris quadricincta and the Dotted bee-fly hides in cracks Bombylius discolor. Bare ground is a key soft cliff habitat which and under lumps of clay offers nesting sites for burrowing bees and during the day, Many soft cliff sites have been given statutory wasps, hunting grounds for visual predators emerging at protection as Sites of Special Scientific Interest such as ground beetles and the Cliff tiger beetle night to hunt.