Surveying Hedgerows
Hedgerows crisscross the Norfolk countryside. They add beauty to our landscape, provide corridors for wildlife to move along, and are vital wildlife habitats in their own right. Some may be many hundreds of years old, marking the position of ancient boundaries, others will have been planted at the time of the Enclosure Acts (1750 – 1860), and many will be of recent origin.
Norfolk has lost nearly half of all its hedgerows; many grubbed out in the decades after the Second World War. Thankfully hedgerow removal is much rarer today now their wildlife and landscape value is recognised. Not only are hedgerows important for the plants that they may contain, but they are also a valuable habitat for many animals, including over 125 of the UK’s most threatened species.
The future role of hedgerows is no longer seen as just a way of enclosing fields. They have an important role to play in helping us to respond to climate change. These linear habitats provide protection to soil, livestock and property from extreme weather; help wildlife to move in relative safety from one habitat to another and they even help to lock up carbon.
Let’s hear it for hedges…
A 2km hedgerow has the potential to store between 1,200 to 1,600kg of carbon dioxide, and there are more than 475,000km of managed hedgerow in Britain. The average car generates this much carbon dioxide by travelling 6,000 miles.
When is a hedge a hedge?
Generally a hedgerow is defined as any line of trees or shrubs, over 1m talk and over 20m long, less than 5m wide at the base and with less than 30% of the hedgerow being gaps.
Hedges function to create boundaries, and most have been developed by farming activity, many as stock-proof barriers to control livestock. Hedgerows are also commonly planted to form boundaries both within and between gardens, and these are also important for wildlife.
Hedges provide not just one habitat for wildlife but many: from dark, twiggy interiors, sunny outside edges, to dead wood and deep piles of fallen leaves. These varied habitats, a bit like a woodland edge, support a huge diversity of wildlife.
To view the Norfolk Habitat Action Plan for hedgerows visit
www.norfolkbiodiversity.org
Why not start a simple survey today?
Do not be daunted by the idea of a hedgerow survey. Start with a simple survey – no one is expecting you to survey hedgerow in your parish. Begin by making a few decisions:
1) Where is your survey area?
Mark your survey area on a map and then decide how much you are going to survey. You do not need to include every hedgerow, if you are working on your own you may just want to do a sample survey – surveying just one or two hedgerows.
2) Over what period of time are you going to carry out your hedgerow survey?
Do you want to carry out the survey over one year, or do you see it as more of a long-term project? The amount of time you can spend on the project will definitely influence how many hedgerows you can survey.
Hedgerows are usually surveyed between April and October, with June and July being the best months – especially if you are recording ground flora.
3) How much of the hedgerow are you going to survey?
(include pictures of different hedges and the sizes)
4) Which side of the hedge should you survey?
There is no wrong or right answer to this question. Ideally both sides of the hedge should be surveyed, but if this is not possible survey the side that has the easiest access. If the hedge is bordered on one side by a road, for health and safety reasons, you may wish to record the opposite side. The key thing to remember is to make a note of which side you surveyed.
Equipment
- Ordnance Survey maps 1:25,000 and 1:10,000
- Compass – to measure the direction the hedge side you survey is facing
- Tape measure to measure survey area
- 1m x 1m quadrat to record ground flora
- Hand lens
- Identification guides
- Camera
Need some inspiration?
Discover just some of the hedgerow surveys people have been carry out in Norfolk.
Would you like to tell us about your hedgerow survey?
Click here.
Get snap happy…
A digital camera can be quite useful during surveying either to record the character of the hedge, or to take photographs of an animal and plant that needs to be identified.
Need help identifying that mystery animal or plant?
Hedge your bets…
Take part in a workshop to help improve your plant and animal identification skills. Check out our
event section for further information.
For all your hedgerow surveying needs…
You may find the following books, dvds, cds and equipment helpful when carrying out a hedgerow survey:
Please watch this space we will be updating this section shortly.
Get the low down on Norfolk hedgerow wildlife
Related questions
Surveying hedgerows – How do we find out if our parish used to have more hedgerows?
Comparing old maps with more recent maps and aerial photographs can help reveal what has happened to the hedgerows in your parish. Looking at tithe maps, enclosure maps, estate maps and early editions of the Ordnance Survey may help you create a picture of where hedgerows were planted in your parish. The Norfolk Records Office would be a good starting point in your search for old maps, or you may like to take a look at these websites:
First edition Ordnance Survey Maps –
www.old-maps.co.uk
Faden’s Map of Norfolk (1797) –
www.fadensmapofnorfolk.co.uk
Norfolk Domesday Book –
www.domesdaybook.co.uk/norfolk.html
Your research may reveal hedges in your parish that are quite old (dating before the enclosure acts of 1750 – 1860). Some hedges may even be formed from remnants of ancient woodland; surveying hedgerows such as these is definitely worthwhile.
Surveying hedgerows – How do I find out where the hedgerows are in my parish?
Aerial photographs can give you a birds-eye-view of your parish and these can be viewed on such sites as:
www.maps.google.co.uk
www.bing.com/maps
The aerial photographs can be used to plot the hedgerow network in your parish and help you decide where to start surveying hedgerows.
Take care…
It can sometimes be hard to distinguish features on an aerial photograph. Low hedgerows may be confused with ditches and vice-versa. Aerial photographs are a good starting point to finding your parishes’ hedgerows, but before you plan a more detailed hedgerow survey you should visit the site to make sure it does actually exist.
Surveying hedgerows – How do I find out what wildlife is found in our hedgerow?
It should not be underestimated how important hedgerows are for many different species of wildlife. Wildlife that once lived in the woodland that covered much of Britain has now been pushed into these far more linear habitats.
In the UK over 1,500 species of insect, 65 species of bird and 20 species of mammal have been recorded living in hedgerows. Several declining bird species, including yellowhammer, corn bunting, tree sparrow and turtle dove, nest in or close to Norfolk's hedges.
These linear habitats are a valuable source of food for many animals and act as wildlife 'corridors', allowing animals to travel from one habitat to another. Once you have begun surveying hedgerows in general (survey form q) you may like to have a go at surveying butterflies, mammals or birds found along your hedgerow.
Surveying hedgerows – How do I carry out a simple hedgerow survey?
Once you have chosen the area in which you intend to be surveying hedgerows, start by marking on a map (this can be a sketch map you have drawn yourself) the following details:
- The hedgerow that you are surveying.
- The beginning and the end of the hedgerow.
- The direction in which you surveyed.
- The side of the hedge you surveyed.
Once these details are captured on the map you need to ask yourself these questions:
What is the shape of the hedgerow, and what condition is it in?
The physical structure of a hedge is important for wildlife. Dense, thick, tall hedges are much more wildlife friendly than short, thin, gappy hedges.
What habitat features surround the hedge?
Hedges are an important habitat for many different species. A hedge containing or adjacent to other habitats, such as tussocky grass or wet ditches, has the potential to attract a greater number of species.
What are the adjacent land use/features to the hedgerow?
The surrounding landscape of a hedge can impact on the wildlife value of a hedge; for example, a hedge surrounded by grass margins or a bank or stream is more likely to have a greater biodiversity then a hedge bordered by a busy road or an arable field which has been ploughed right to its edge.
Survey the hedgerow plants
First decide how much of the hedgerow you are going to survey and mark these areas on a map.
1) Record the trees and shrubs in each section
Use survey form r
- Identify all the woody species present.
- It is not necessary to count the number of individual plants of each species.
- If the species has been allowed to grow into a tree, describe it using the following key:
- N = newly planted
- S = standard tree
- C= coppiced
- P = pollard
- D = dead tree
- A = ancient tree
2) Record the climbing plants present in each section
Use survey form r
Identify all the climbing plant species present. There is no need to count each individual plant; simply tick the box to indicate that they are present.
3) Record the ground flora in each section
Use survey form s
Put down two quadrats (1m x 1m) as close to the base of the hedge as possible, within each 30m section; one at 10m and one at 20m.
Record all the species you see in the quadrat.
If may also be useful to estimate the species dominance using the DAFOR scale within the quadrat.
Surveying hedgerows – How do I find out how old a hedgerow is?
When surveying hedgerows you believe to be ancient, you might want to ask yourself these questions:
-
- 1) Does the hedge appear on an old map?
-
- 2) What shape is the hedge on a map? (Very ancient hedges are likely to have a wavy or irregular ‘s’ shape. Long, straight hedgerows are likely to be modern, or have originated during the enclosure acts.)
-
- 3) Are there any ancient woodland indicators at the base of your hedge?
-
- 4) Does your hedgerow contain an ancient tree?
-
- 5) Does your hedge contain spindle, dogwood, field maple or Midland hawthorn? (In Norfolk, the presence of these species may indicate that it is an ancient hedge - especially if several of the species are recorded. A hedge containing many different species of woody shrub is often older than a hedge with only one or two species.)
Remember that ancient hedges are one of the UKs most valuable wildlife habitats, so see if you can discover any local ones!