This hawthorn hedge is quite young, and although it is quite dense and healthy, the arrow shows that the base canopy is quite high. Base vegetation is incredibly important for many of the species using hedgerows, and a high base canopy is often a sign that a hedge needs rejuvenating. In this case, however, this was a result of leaving the tree guards on, resulting in little branching in the lower foot.
This hedgerow is now full of elder. Although elder is a fantastic plant for wildlife, it can be a sign of a hedge in trouble. Elder is quick to colonise hedgerow gaps so can be a sign of a thinning hedge, perhaps one that needs a change in management. Elder will not be stock proof in a hedge, doesn’t respond well to the typical hedge management that leads to its presence, and each plant is unlikely to live long.
The green arrow here represents the high base canopy typical of a historically over trimmed hedge. The blue lie shows how much of the hedge is occupied by one plant – this is because the hedge stems will have thinned during previous over-trimming. The pink arrows show consecutive raised trim lines – very positive sign of much needed change of management. Ideally this hedge would be rejuvenated soon, with gaps planted up.
This hedge has been massively over-trimmed in the past. The lower arrow shows the height this hedge was trimmed to for a very long time. This is now the line that most of the growth comes from. You can see that few hedge stems remain, and they have lost their lower vegetation. More recently the cutting height has been raised to the top arrow. This is great and will likely have saved this hedge, although in an ideal world it would be rejuvenated.
This hedge shows the line to which it was previously trimmed, before it was ‘let up’. There are signs of the need for this, such as the gaps emerging between the stems, example shown by blue arrow. This hedge is now perfect for rejuvenation through laying.
We measure nettles, docks and cleavers at the base of the hedge as a proxy for excess soil nutrients. Although these plants all have an important part in our ecology, they can signify where a hedge has been exposed to too much fertiliser. This has a negative impact on the wildflowers that may otherwise have thrived there. This photo sees a particularly bad case, the hedge is swamped in cleavers and the margin is 100% nettles docks and cleavers.
This hedge looks like an otherwise healthy H7 hedge. There is no obvious signs that point to why this gap has occurred. With either side managed a little to allow light in, it would be a great opportunity to plant a hedgerow tree.
This is an overgrown hedge that has lost its base vegetation through both shading and grazing. The blue arrow shows the very high base canopy. The tops of these plants are spreading and the pink arrow shows where gaps are forming between stems. This hedge is far from stock-proof and would benefit from being rejuvenated.
This was a hawthorn hedge that was left without any management for a number of years, This has now turned into a line of hawthorn trees. The base canopy (pink arrow) is very high, and as these trees collapse (purple arrow) the gaps between them are getting larger (blue arrow). This is in desperate need of rejuvenating, through laying if the stems will allow, or coppicing and planting up the gaps.
This is a hawthorn hedge that is showing signs that it needs laying. The sides are trimmed, but the tops are spreading (you can’t see in this picture). This has shaded out the growth in the base of the hedge, resulting in this leggy appearance with high base canopy, shown by the pink arrow. The stems are still fairly young and frequent so it will be a great hedge again once layed.
Hedge connections are often easier to see from aerial maps. The hedge marked in orange here has 3 connections on the north end, and the woodland at the south counts as 2 connections.
Although this at first looks like a low hedge, the actual woody structure of the hedge has gone and this is just a line of brambles. While bramble is a hugely important part of our ecosystem, and fantastic for wildlife in general, this is symptomatic of a poorly managed hedge that is becoming gappy and at risk of disappearing. Where woody structure ahs been replaced by bramble, we class this as a hedgerow gap.
While this hedge may look dense and green, the structure is actually dead. Whilst ivy is a fantastic plant for wildlife, and an important part of our ecosystem, too much ivy at the surface of a hedge can be an indicator that the hedge is over-trimmed to the same point repeatedly. Ivy can survive behind thin hedge foliage, and creates almost a wall of leaves at the trim line. This prevents light getting to the rest of the hedge and can hasten the demise of a hedge that is already struggling. A closer inspection of this hedge shows the dead structure of an old hawthorn hedge behind, which will eventually collapse.
This is the trim line of a hazel hedge. You can see the knuckle like scar tissue that indicates that this hedge is regularly trimmed to this point. It is a good indicator that management needs to be changed to increase the height of the hedge at the next trim.
The blue arrow shows the high base canopy of a historically over-trimmed hedge. The stems have thinned and are now quite spaced out. The pink arrow shows where this hedge used to be trimmed to for a long time. This hedge has since been ‘let up’, and the green arrow shows the amount of growth it has put on since it was last trimmed. All this new growth comes from the trim line, so this will need to be layed in the near future before the weight of this new growth collapses the stems.
When a hedgerow has been left unmanaged and grows into a line of trees, how do you count hedgerow trees? In our survey we count only trees that are, or have been, managed distinctly from the hedge. In this hedge, the oak on the right has obviously been managed as a tree, distinct from the hedge, where the other stems are simply the result of no management. In this case, this would be the only ‘tree’ to record. Clues are in the age and the structure of the tree, this one is older and has more branching structure indicating it grew up with less light competition than those around it.
This fragment of a hedge shows what happens if management isn’t altered when signs of damage first appear. In over-trimmed hedges, gaps form then get larger and larger (pink arrows) until you are left with isolated shrubs, and eventually no hedgerow at all. The blue arrow shows a very high base canopy of the fragment, showing how intensively over-trimmed it is.
The green arrow shows the gap in this over-trimmed hedge. The intensive trimming regimen has caused many stems to die, leaving these gaps. As a result of the trimming, the growth between the stems, in these gaps, is the only growth that is not trimmed off, giving the impression that the hedge is stretching to fill the space. In spring, these are sometimes the only patches that blossom on hedges over-trimmed in this way.
This hedge has been recently layed and is already showing fantastic re-growth. The pink arrow shows a ‘pleacher’; a stem that is cut almost through and bent over to stimulate regrowth. The green arrow shows how much re-growth this hedge has put on since being layed.
This is a young hedge. The pink arrow points to tree guards added when it was planted to stop deer and rabbit damage. Left on too long, this can cause a higher than ideal base canopy (blue arrow) but this will be remedied the first time it is layed. It looks like the hedge was planted with the 5 stems per metre, in two staggered lines. Laying this hedge will help create a thicker hedge in the long term.