Record significant damage to vegetation by M. Alexander, E. Stubbings and B. Bueche

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1 Record significant damage to vegetation by M. Alexander, E. Stubbings and B. Bueche There have been a number of quite significant incidents when areas of coastal vegetation have been damaged. The worst on record was at Skomer Head in 1975 when the vegetation was killed over an area extending from the headland to the ridge of rock north of the enclosure and from the cliff edge inland well beyond the current footpath. The vegetation took almost a decade to recover. The damage at Skomer head was attributed to an extreme gale during 1974 when the area was saturated with salt spray. However, this was by no means an unusual occurrence; Skomer Head is frequently drenched with sea water during the winter gales with no consequential dieback of vegetation. The damage, when it occurs, could be the concurrence of several different factors, these might include; dry conditions prior to the gale which allows the soil to become saturated with salt water, low rainfall after a gale with the consequence that the salt is not flushed away, and, the vegetation in a vulnerable state following prolonged dry or drought conditions. The entire area at Skomer Head was riddled with Shearwater burrows; this could have increased the impact of all of the other factors. In 2016 there was a major die off of vegetation at North Haven and the Neck. The 2016 incident was quite different to the Skomer head experience when all the vegetation was killed, in 2016 an excellent sequence of photographs, taken by the Warden, reveals that the die back was almost entirely restricted to Holcus lanatus, the maritime species, Silene and Armeria survived as did the deep rooted species, including Urtica dioica and Sonchus spp. Bracken was also unaffected. Following the winter 2016/17 the Holcus appears to have recovered. The slopes in North Haven were often bare during the latter half of the 1970s following the extreme drought years of 1975 and 76. Rainfall on Skomer was more or less average during 2016 with no obvious unusual or exceptional events. It is unlikely that the dieback could be attributed to drought. Rabbits are always a variable influence, in general they apparently avoid Holcus, it is not particularly palatable, however, on Skomer when there is nothing else available they will graze it. The species that survived are all unpalatable and avoided by rabbits. There is no obvious single factor that can be associated with the dieback. There is concern that the loss of vegetation can lead to the collapse of burrows and wind erosion of the soil, this is a particular problem when research sites are affected and the area becomes extremely fragile. It is possible that in the future a serious coincidence of factors could have a much more significant impact on the vegetation and in particular this could threaten the burrowing birds. It is important that all incidents are recorded. The standard for recording was established by the wardens in 2016 and this should be repeated whenever there is future cause for concern. 1. Photograph all the affected areas, once the damage becomes apparent, and at intervals of c 6 months following the initial damage. Continue with photography until the vegetation has recovered to a point where it is indistinguishable from neighbouring unaffected vegetation. 2. Map the affected areas as accurately as possible. 3. Consider the weather, in particular storms, periods of drought or other exceptional events, during the previous year or so and look for possible cause. 4. Establish additional permanent quadrats; see above, in any affected area. 5. Record any damage to burrows.

2 There is no obvious management action, but the reserve wardens should closely supervise any research activities in damaged areas to ensure that there is no unnecessary risk of damage to the burrows. In the event of a serious incident in the future, if recovery is slow, the managers should consider temporary rabbit exclusion. North Haven next to Warden s House

3 Hill behind Warden s House Slope behind Warden s House looking towards South Haven

4 Slope behind Warden s House towards Captain Kites Slope to landing

5 Slope to landing Neck overview

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