What’s in a hedge?

What’s in a hedge?  

 

 

It will come as no surprise to most of you that I have an interest in hedges at present. I have recently spent many happy weekend hours in a damp, muddy field digging little holes in stony ground and inserting wee whips of hawthorn, hazel, rose, whitebeam, dogwood and blackthorn.  

 

Northern Ireland has the highest density of field boundary hedges in the UK which gives us the impression of a wooded landscape whereas, in fact, the island of Ireland has the lowest native woodland cover in Europe. So, the abundance of hedgerows goes some way to making up for the lack of deciduous woodland and hedgerows are an important habitat for a wide range of wildlife, supporting all levels of the food chain. 

Although there are some ancient hedges in Northern Ireland, most are substantially younger than in the rest of Britain where hedges can be upwards of 1000 years old, Northern Ireland’s hedges typically originate from between 1750 and 1850. These hedges form the traditional boundaries between parcels of land: townlands, parishes and individual fields. As a general rule, the older the hedge, the greater the variety of tree and shrub species it contains and will be better support for a wide variety of woodland plants. 

The majority of hedges in Northern Ireland are composed of native flowering and fruiting trees and shrubs with hawthorn (aka whitethorn or May tree) being the most abundant species but they may also include a mixture of blackthorn, elder, hazel, wild rose, honeysuckle, ash, oak, rowan etc. According to the UK Action Habitat Plan, a hedge which contains five or more native tree species in a 30m length is considered to be species rich. 

A hedge containing a richness of plant species in turn supports a wide range of wildlife. Some of the native species of tree common in Northern Ireland hedges support a huge array of fauna. Hawthorn has more than two hundred species of insects which depend entirely on it as a food source and it can support around 300 species (including carrion eating pollinators attracted to the sickly scent of its blossom which is said to be reminiscent of rotting flesh, the connection with death could be the reason that it is considered unlucky to bring hawthorn into the home).   

Willow and oak trees within a hedgerow can support over 400 invertebrate species each. In comparison the non-native sycamore, field maple and horse chestnut will support fewer than fifty species of insect each.  

In turn the invertebrate population of moth, butterfly and fly larvae, the spiders, beetles and other insects support a population of carnivorous and omnivorous birds and mammals including bats, hedgehogs and larger itinerant mammals.  

According to the Countryside Bird Survey in Ireland, 110 bird species use hedges for roosting, breeding, nesting, feeding and perching on song posts.  Hedgerow fruit feeds blackbirds and thrushes from late summer into winter however a migratory flock of redwing can put an abrupt end to other thrush species feeding on hawthorn as a large flock can completely clear a hedge of berries within half an hour of a landing. Herbivores such as field mice, dormice (spreading quickly from Co Kildare since 2010), voles use all layers of a hedge and ground dwellers, like rabbits thrive in the under hedge. Hedges are in constant use as primary or secondary habitat, as shelter from weather and predators and a safe passage along the sides of roads and across countryside. 

In the past 50 years the number of healthy hedgerows in Northern Ireland has declined radically, most lost to housing developments and road widening schemes. Many older field hedges have been neglected and left unmaintained or over cut with tractor mounted hedge flails which destroy the fruiting branches leaving them vulnerable to disease. Many were replaced by wire fencing but in recent years, owners of agricultural land in Ireland, both north and south, have been offered grants to plant new species rich hedges.  

 

My undertaking in the field of hedges doesn’t fit into any of the current schemes and incentives as I’m filling gaps between old hawthorns rather than creating entirely new hedges. But I’ll just carry on, maybe in 50 years my efforts will be seen to have had a positive impact!