Tayside Biodiversity Partnership Local Action Plan

Hedgerows and Treelines

DEFINITION
Hedgerows are generally classified as continuous linear scrub less than 4m high. Within the context of this Habitat Action Plan hedges will include boundary features such as hedgerow trees and treelines. Extended hedges are lengths of hedgerow adjoined by wide grassy margins left unploughed in arable areas and fenced off in areas grazed by livestock.

CURRENT STATUS AND EXTENT OF HABITAT
Hedgerows remain an integral part of the lowland farm landscape in Tayside. Whilst important for cultural and landscape reasons, hedges play a vital part in maintaining the biodiversity of Tayside. Significant lengths of hedgerow exist
throughout the region, although the length of hedge lost between 1940 and 1980 was around 1,000km - 25% of the estimated total of 4,000km.

Whilst conservation management techniques for hedgerows are generally well known, neglect and decline in the quality and quantity of hedgerows still occurs in Tayside and throughout the UK.

KEY SPECIES

P = UK Priority species C = UK species of conservation concern

Mammals	Stoat	Mustela erminae	C
	Weasel	Mustela nivalis	C
	Common shrew	Sorex araneaus	C
Birds	Grey partridge	Perdix perdix	P
	Bullfinch	Acanthis cannabina	P
	Linnet	Pyrrhula pyrrhula	P
	Reed bunting	Emberiza schoeniclus	P
	Song thrush	Turdus philomelos	P
	Yellowhammer	Emberzia citrinalla	C
	Tree sparrow	Passer montanus	P
Invertebrates	Ringlet butterfly	Aphantopus hyperantus
Plants	Oak	Quercus robur
	Ash	Fraxinus excelsio
	Hawthorn	Crataegus monogyna
	Blackthorn	Prunus spinosa
	Common knapweed	Centaurea nigra

NATURE CONSERVATION IMPORTANCE
Lengths of hedgerow play an important role in the maintenance of species diversity. Much of the land in Tayside consists of cultivated arable or intensively managed grassland. These land use types provide only a limited amount of habitat for invertebrate, bird and mammal species. Therefore field boundary features have an extremely important role to play in terms of maintaining farmland biodiversity. Over 600 species of plant, 1,500 of insects, 65 birds and 20 species of mammals have been recorded feeding or living in hedgerows at some point in their life cycle.

Sympathetic management also determines the conservation importance of hedges. Large, wide, bushy hedges support about 19 different species of bird whilst mechanically tidy, frequently cut hedges support only about 8 breeding species.

Hawthorn

Our word for hedge derives directly from the Saxon “ haeg”; hawthorn means “hedge-thorn” having been intrinsically part of our hedgerow tradition for well over a millennia. Many plants and animals are eponymously associated with hedges – Hedgehog Erinaceus europaeus and Hedge parsley Torilis spp. to name but two. There are in fact over forty traditional hedge names used for a wide variety of species throughout the UK including the ‘hedge sparrow’, a name once commonly used for the Dunnock Prunella modularis.

Much planted during the 18th century, the hawthorn is still used as the main shrub in our hedges today as its spiny character deters livestock from straying. Left to grow on, the hawthorn becomes a small bushy tree much loved for its ‘may blossom’. There are over 1,000 different species of Hawthorn throughout the world.

“ The Bread and Butter” Tree has long been used by man not only to stave off hunger, but since the 19th century it has been widely used on a global scale as a heart tonic to regulate circulation. It also helps lower cholesterol, aids digestion and has a mild sedative action. Over 200 European commercial medicines use hawthorn as their main constituent.

Hedgerows can offer nest sites for UK Biodiversity Action Plan species such as Song thrush Turdus philomelos and Linnet Pyrrhula pyrrhula, whilst Grey partridge Perdix perdix and Yellowhammer Emberzia citrinalla often nest on the ground in the bottom of hedges, particularly where there is a wide grass margin. Yellowhammers and Song thrushes also rely on hedgerow trees as song posts, whilst Kestrels Falco tinnunculs and Barn owls Tyto alba often use them for hunting. Old trees often found in hedgerows and treelines provide important roost sites for bats such as Pipistrelle Pipistrellus pipistrellus, Natterer’s Myotis nattereri and Daubenton’s Myotis daubentoni. Birds, including the Tree sparrow Passer montanus, whose numbers have plummeted to only 11% of their original population, use holes in dead trees for nesting. Many invertebrate, lichen and fungi species are associated with old hedgerow trees, especially oak.

Hedges are also excellent ways of linking different wildlife sites providing ‘wildlife corridors’. Bats use hedges as navigation aids and prefer flying along hedges and treelines than to flying across large fields. Other species, particularly invertebrates such as spiders, ground beetles and hoverflies are often found in hedge bottoms and tussocky field margins. All these insects are significant in assisting with pest control, the hoverflies also
playing an important role as pollinators. Whilst hedgerow trees and treelines can enhance biodiversity there are some situations where their
introduction is less desirable. Ground nesting birds such as the Grey partridge will avoid areas where trees are present. Wading birds such as
Lapwing Vanellus vanellus and Redshank Tringa totanus and songbirds such as Skylark Alauda arvensis need open areas for nesting: they avoid
wooded areas in order to reduce their risk of nest predation. In areas of Grey partridge habitat hedgerow trees should be no closer than one
every 100 metres.

Yellowhammer

The Yellowhammer is found on farmland throughout the UK.

Slightly larger than a chaffinch it is notable for its yellow head and rusty red rump. It generally nests in hedges, scrub, grassy margins and small plantations and feeds on seeds and berries.

Together with the Song Thrush, it relies on mature hedgerow trees which it uses as song posts to reinforce its territory during the breeding season.

The population has seen a decline of 5% in the last 25 years.

NATIONAL BIODIVERSITY CONTEXT

“The UK Biodiversity target for hedgerows is to halt all loss of ancient and species-rich hedgerow by 2005. A target has been set for the favourable
management of 50% of species-rich and ancient hedgerows by 2005.”

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