Area: 45.3 hectares.
Description and Reasons for Notification:
Arlington is important for its rich lichen flora with many rare species. It also supports a good assemblage of invertebrates, including national rarities.
Lying within an altitude range of 100 matres to 180 metres the parkland has a mainly south-westerly aspect and the underlying Devonian slates provide a thin, well drained soil. The most important trees here include ash Fraxinus excelsior, oak Quercus spp., and beech Fagus sylvatica. The parkland slopes more steeply towards the valley bottom where the river Yeo flows in a southerly direction via a large lake. A dense carr has formed around the northern end of the lake with willows Salix spp., and alder Alnus glutinosa dominating the canopy. Further downstream there is an additional area of carr with ash, oak and hazel Corylus avellana becoming more frequent. There are several large, mature oaks here, some of which have collapsed, and there is an abundance of well-rotted trunks and limbs.
The diverse conditions of the ancient parkland and willow carr provide for a rich lichen vegetation with some rare western and old-forest indicator species. Of particular note here is the development of Cetrelia olivetorum and Heterodermia obscurata which is the best in south-west England. Also important is the presence of Teloschistes flavicans, one of only two localities for this species in Devon outside the southern coastal area. Rare species include Bombyliospora pachycarpa, Pannaria conoplea, Parmelia lacinatula, Sticta dufourii and Lecidea carrollii. The Lobarion community is well represented and the site is also noteworthy for an abundance of Usnea articulata.
Amongst the invertebrate fauna are two nationally scarce beetles Chrysolina haemoptera and Pterostichus oblongopunctatus and several local beetles including the rhinoceros beetle Sinodendron cylindricum, Biphyllus lunatus, Cerylon ferrugineum and Pediacus dermestoides. The nationally rare high brown fritillary butterfly Argynnis adippe and the local snail Zenobiella subrufescens have also been recorded.