Before you start the Great British Hedgerow Survey
Get permission - Whether you are surveying hedges as part of a wildlife group, a hedge group or contributing as an individual, if you do not own the land you will need to check with the landowner that they are happy for you to survey and send us this survey data. Please do not upload any data for which you have not got permission to share.
When to survey - For this survey it is important to be able to identify the woody species in your hedge, so we recommend doing this survey in any season that the hedges are in leaf, most likely April to October. Although it is possible to identify these species from their twigs, it is more likely that some species get missed and the hedge data doesn't reflect the true diversity of the hedge, it is also nearly impossible to accurately estimate the % coverage of species when their leaves are not out.
Check your tree ID skills - As part of the survey, we ask you to tell us which woody species are growing in a 30m sample of your hedge. Before you go out it may be worth checking that you are comfortable identifying the species on our survey form list. If not, this is a great opportunity to scratch up on your tree identification skills! There are many fantastic guides to help you identify native tree species, so if you have a favourite guide or book do take it with you. Alternatively there are some great online guides that might help you, like this A-Z of UK native trees from the Woodland Trust or download this rough guide to hedges from CPRE.
Some of the questions of this survey relate to observations of the whole of the hedge you are surveying, and other questions should be answered for a 30m sample of this same hedge. The survey form should make it clear which questions relate to the whole hedge and which relate to the sample.
What you will need
- A survey form (download here) for each hedge or complete the survey directly to this website
- A measuring stick, preferably 2m or so, marked at 10cm intervals
- An ID guide to common British plant and tree species
- Appropriate footwear
- Survey instructions
- Hedge structure key
How to survey
Where does the hedgerow start and end?
Hedgerows in the countryside form a network, with many hedges linked together. For the purposes of this survey, we need to define a ‘start’ and ‘end’ point for the hedge, which we will call ‘nodes’.
The circles on this diagram show the nodes. The numbers show the number of connections at each node circled.
- Where another hedge meets your hedge
- Where there is a gap in the hedge of 20m or more
- Where hedge structure changes dramatically for 20m or more
- Where your hedge meets another feature such as a wall or woodland
- Where your hedge turns a corner of 90 degrees or more
- The number of other hedges your hedge is connected to at each node.
- A hedgerow ending in woodland counts as two connections on that end.
- If there is a gateway or opening (less than 20m) at the node, count the hedge(s) that would otherwise have attached
Tip: When measuring out the length of the hedge, as well as your 30m section, it is helpful to know the average length of each step, or how many steps you take to reach 5m. This will be much easier than using a tape measure all the time.
ure of the hedge does not meet. Please include both small and large gaps in your calculations.
30m sample of hedge
Which 30m of this hedgerow do I survey?
The 30m sample of the hedge should be representative of the rest of the hedgerow, and ideally not at either end of the hedgerow. You can only know what is representative after walking the length of the hedgerow you are surveying.
How do I measure the height and width of the hedgerow?
Both the height and width measurements of the hedgerows should measure from the start of the woody vegetation. For example, if the hedge was on a bank, but the woody component of the hedge only started half way up the bank, then you would measure from this point to the top of the hedge. Herbaceous vegetation and brambles should not be counted in this measurement.
Tip: Taking a tape measure with you is important to these measurements, but also a stick up to 2m long can be a really useful tool to poke through hedges to measure their width and height. Even better is if this stick is marked at regular known intervals. A Second pair of eyes is also advisable, only this way will you know when your marker stick is through to the other side of the hedge, and they can get a better estimation of height if they step back for a better perspective.
What is the base canopy and how do I measure it?
The base canopy is the lowest leafy growth coming from the structural woody plants in the hedge. In cases where the hedge is extensively grazed, where it is overgrown and ‘leggy’ or where tree guards have been left on a young hedge too long, this base canopy may not extend to the ground. Please estimate the average height of this canopy from the floor, excluding herbaceous vegetation.
Hard knuckle at trim line
When repeatedly trimmed at the same level, the woody hedgerow plants develop a knuckle like appearance at this trim line. This is the accumulation of plant scar tissue, and can sometimes be seen by an increased number of shoots growing from this point.
Measuring undisturbed ground and perennial vegetation
Average width of undisturbed ground, ‘a’
Measure this from the trunks/bases of the woody component of the hedge to where there is any management that may damage the roots, such as ploughing or a road. Any hedgerow that is adjacent to any undisturbed vegetation such as permanent grassland or woodland will automatically get full marks for this.
Average width of perennial herbaceous vegetation, ‘b’
This is a measure of the perennial herbaceous habitat at the base of a hedge that is so important for shelter, foraging and nesting animals. This habitat may be reduced by intensive grazing or herbicide use. It may include brambles, grass or other perennial herbs.
In these images, distance ‘a’ denotes the undisturbed ground, distance ‘b’ the perennial herbaceous vegetation and the grey rectangle shows where ground disturbance starts.
Diagram 1 shows a hedge where the undisturbed ground and width of perennial herbaceous vegetation are the same.
Diagram 2 shows a hedge where the perennial herbaceous vegetation is narrower than the width of undisturbed ground as the ground under the hedge is bare through shading.
Column 1 - Shrubs present
Column 2 - % coverage of the top 5 most dominant species
Columns 3 & 4 - Isolated hedgerow trees
Please count and record the tree species in the whole hedge you are surveying.
Column 3 logs 'mature' trees; any tree more than 20cm diameter at breast height (dbh) should be logged as a mature tree for these purposes.
Column 4 logs 'young' trees; in this case we say that a tree
Please do not feel like you need to go in the hedge and physically measure each hedge, when you get an eye in for what 20cm dbh looks like, feel free to judge this by eye, with perhaps the occasional measurement to calibrate your judgement.
If you are looking at a multi-stemmed maiden tree, please just assess the dbh of the main stem. If the tree forks below breast height, measure the diameter below the fork. If you think you are looking at a coppiced tree, look at the diameter of the base of the coppice stool.
Please do not include woody shrubs that make up the structure of the hedge, only those that have a clear stem and are obvious as individual trees with isolated canopies above the height of the main hedge line.
This can be more challenging for hedges of H8 structure and above where the hedge structure plants have grown to a point that they could be described as ‘trees’. For the purposed of this survey, a ‘tree’ should be an individual that is obviously managed differently from the main body of the hedge. In an over-mature hedge do not count the individuals that make up the main body of the hedge, even if they approaching what could be classed as a tree, unless they are clearly identifiable as an isolated hedgerow tree distinct from the rest of the hedge structure.
These trees must be in the line of the hedgerow or the nearest point of the tree trunk must be less than 1m from the edge of the woody canopy of hedgerow.
Once complete, you will be given a review of the information you have added and the option to go back and edit any detail before submitting the data. When you submit the data, condition assessment and management advice will be generated from your results.
The management advice generated from this survey is based on the hedgerow management cycle and relies on you filling out each field of the survey. If you are aware of any plant insect or animal species in your hedge, rare or otherwise, that have more specific management requirements, please seek further advice before proceeding.
Management of a site should certainly take the landscape approach, and the local area should be considered before engaging in management. Taking the cycle approach to management means hedges over the site will be in different stages of their lifecycle. This is to be encouraged and improves the number of different niches available to wildlife. We recommend that no more than 5% of the hedges on any site should be layed or coppiced in any one year as although they rejuvenate the condition of the hedge in the long term, they reduce the connectivity and habitat for wildlife in the shorter term.
This tool gives you information about the best way to manage as part of a cycle, but you will need to contextualise this within your setting, e.g roads and routes should be managed for safety as you otherwise would.