From urban parks to ancient woodland, every habitat can be improved to make it more valuable for wildlife and more interesting for the local community. Even simple changes, like allowing grass to grow longer, can add colour and life.
Sometimes the reasons for our habitat management might be unclear and the work might seem dramatic or counterproductive. Here are answers to some common questions about what we do:
Why do we not always keep grass tightly mown and ‘tidy’?
Cutting grass less often is a very simple change in management that can make a real difference to wildlife.
Areas which are less frequently used by the public can often be mown just once each year in the early autumn. This creates habitat for flowers and insects, and if it’s well-located, it makes the whole site look more interesting too. In some places cutting can even take place less than once a year. Long grass left through the winter is excellent for insects.
It’s particularly good to do this along existing features like hedgerows. This protects what is there already, and helps build a corridor of natural habitat.
Introducing native wild flowers
Years of regular mowing leaves little variety of flowers growing in a grassy area. Planting new wild flower seed adds colour and attracts wildlife when grass is allowed to grow long.
Cutting the grass late in the year allows plants to flower and set seed, but long grass can easily dominate in some places. With the right seeds added, the same place can be full of colour throughout the summer, and excellent habitat for insects.
The best way to do this is to break up the surface, exposing bare soil, then scatter the seed and roll the ground. It may look messy to start with, but within a few years the benefits will be clear.
What happens to grassland if you leave it uncut?
Grassland needs to be cut just to remain as it is. Left to itself, taller plants and then bushes will quickly take over. The longer this natural process continues, the harder it becomes to reverse.
Grassland management techniques – cutting and grazing
Grass needs to be managed just to remain as it is. This can be done by cutting or grazing. Cutting works best on small sites and grazing can be better on large sites.
Cutting is a really flexible option. Depending on the needs of the site, you can change the timing, the frequency, the area and the height of the cut. Cutting for conservation is best delayed until plants have had a chance to set seed.
It’s also vital that the cuttings are removed. This helps any fragile plants to survive and prevents soil fertility increasing. High soil fertility tends to reduce the variety of plants in an area.
Grazing is more traditional and more sustainable – it produces meat as an end product. It’s the best way to maintain interesting grasslands, full of variety, because of the way animals eat selectively. As animals need fencing and regular checks, it also needs much more commitment. It’s more difficult on smaller sites, where it can be harder to accommodate the needs of all site users.
When grazing, we need to think very carefully about how many animals we need, and for how long. Grazing too little or too much can both be a problem, either by allowing large plants to dominate or by creating too much bare soil.
Grazing cows returned to Chorleywood Common in 2009 after a long gap. Bringing back grazing here benefits the wildlife on the site and makes its management more sustainable in the long term.
Cows and people
Cows are fantastic land management tools. They’re traditional, sustainable and effective, and they can add real character to a site. Yet until recently they had largely disappeared from Hertfordshire.
We are now trying hard to reintroduce grazing to important sites in the county. Unfamiliarity can cause people to be concerned about bringing cows back into the landscape, but with good planning it shouldn’t be a problem.
On a public site, the breed and individual animals should always be chosen for their good temperament. On site information boards will provide advice on how to behave around cattle, in particular the need to keep dogs on leads.
All these precautions make the risk of physical danger from the animals extremely low.
A well-planned grazing scheme may also include a trial period to give people a chance to get to know the animals. Access should never be affected, and on larger sites it can be possible to restrict grazing to certain areas, helping people who don’t want to walk amongst cattle to continue to use the site.
Walking dogs around cows
The countryside is a great place to exercise dogs, but it’s the duty of the owner to ensure that their dog isn’t a nuisance or a danger to farm animals. It’s also safer when walking amongst cows for your dog to be under close control.
Even if you’re used to letting your dog run around a particular field, you should take extra care when cows are grazing. On council-owned sites, these animals are introduced for part of the year to help manage grassland. They will have been specifically chosen for their good temperament, but it is still dangerous for the cows, the dog and anyone in the field if cows are chased by a dog. This doesn’t mean you need to avoid the cows completely. Just keep your dog under close control when walking through a field that contains cows.
In the unlikely circumstances that you and your dog are chased by cows, don’t risk your own safety trying to protect your dog. Let your dog go – it will be able to run away.
Why are you allowed to put up a fence on common land?
Fencing can be a vital management tool, in particular by allowing a common to be managed traditionally using grazing animals. This keeps the common in the best possible condition in the long term.
Fencing may be temporary, or if it’s permanent, your right of access to the area will be maintained by establishing an appropriate number of entrance points.
Fencing was erected in 2012 around part of Bricket Wood Common. This meant the management of this valuable site could be improved using grazing animals. Gates were included along all existing paths to make sure that access to the common was not restricted.
Why are you cutting down those bushes?
Bushes often grow when grasslands are left alone for too long. Removing scrub gives the grass and wild flowers a chance to return. There is so little special grassland in Hertfordshire that every piece is valuable. Scrub is much more common, and if it’s left untouched it can completely take over. Once the number of bushes has been reduced, mowing or grazing helps grass and flowers to come back. Even so, many creatures like the combination of scrub and grass, so it’s always good to leave some bushes. It’s best to cut down a small amount each year. As some will grow back, this creates a nice mixture of bushes of different ages. Like grassland but on a longer timescale, scrub needs to be managed regularly just to remain as it is. Scrub management can involve anything from hand-held tools to machinery attached to tractors.
Why don’t you plant some trees?
Trees aren’t right everywhere. There are special grasslands in Hertfordshire which have taken centuries to develop. These places are much more valuable than woodlands because of their rarity. Open spaces are not only important for wildlife. They can also be attractive, and provide space for all kinds of recreational activities. Of course, there are many places where tree planting makes sense. Trees are fantastic things that can be beautiful and full of wildlife. We make every effort to encourage tree planting in the right places.
Why do we cut down trees on heathlands?
Heathlands are open landscapes on acidic soil with a variety of low-growing plants. In Hertfordshire they’re dominated by grasses, but also support characteristic plants like heather. They’re one of the most special places for wildlife in the county. Like grasslands they’re man-made, so they need management just to stay as they are.
Without that management, trees will quickly take over. And in some places trees have been planted on old heaths. Although woodlands can be valuable to wildlife too, they are much more common.
Heathlands survive only in scattered patches, and are well worth restoring where possible, even when trees have to be cut down to do so. This helps a wide variety of interesting plants and animals which are found nowhere else in Hertfordshire.
Croxley Common Moor near Rickmansworth is one of the most valuable wildlife sites in Hertfordshire. Special plants like petty whin and Dyer’s greenweed are an important part of the heathland environment. These in turn support a community of rare insects.
Management of heathlands
Heathlands are managed like grasslands, by grazing or mowing. This stops trees becoming established, and keeps the heath healthy.
Mowing is simple and effective. When different parts of the heath are cut each year, it creates areas with a variety of ages. Not surprisingly, this is better for heathland animals than lots of plants that are all the same age.
Grazing is a more traditional management technique. Grazing animals are the best way to develop an interesting structure in the heath and make it as good as it can be for wildlife. They are a much greater commitment though – they need to be checked regularly, water to drink and fences to control where they go.
Bracken is a natural part of the vegetation in a heath or a wood, but it can easily take over and dominate, suppressing other plants and becoming increasingly dense.
In the past, it was normal to spray bracken with a selective herbicide to control it. That herbicide was banned by the EU in 2012, and although it is being made available on an emergency basis each summer its long term availability is not guaranteed.
Using a specially designed bracken roller helps reduce bracken growth without needing chemicals. The same area needs to be rolled for several years to avoid the bracken recolonising the area. CMS has used a bracken roller on several sites in Hertfordshire.
Why are hedgerows not always cut regularly and kept 'tidy'?
Hedges can be fantastic habitat for wildlife. Even in the middle of towns they provide shelter and cover, somewhere to nest or somewhere to feed.
The best hedge is thick and bushy, with lots of cover. Plants within the hedge like brambles and hawthorn flower, bringing colour in the spring and summer. Later in the year they produce fruit and seeds, providing valuable food through the autumn and winter.
The best way to encourage the production of this natural food supply is to cut hedges in alternate years, or on one side each year. This is because fruits are often borne on growth from the previous year. Cutting less often like this is far better for wildlife – many kinds of bird and small mammal find food in hedgerows.
This doesn’t mean all hedges should be cut less often – there are lots of places like footpaths and formal parks where frequent hedge cutting is still most appropriate.
What time of year is best for cutting?
It is best to cut hedges in the winter. That way birds and mammals get an opportunity to feed on the fruit and seeds that the bushes produce.
The best time of all is February, leaving food on the bushes for as long as possible but avoiding the time when birds start nesting. The most important time to avoid is between March and July because of the bird breeding season – it is illegal to intentionally damage or destroy the nest of any wild bird.
Song thrushes are one of our most familiar hedgerow birds, but they are declining rapidly. Thick, bushy hedges full of insects and snails in the summer and berries in the winter provide excellent habitat for this species, which is as happy in towns as it is in the countryside.
Hedge laying and coppicing
Hedges can easily get overgrown or straggly. At this point they need management more drastic than a simple cut.
Hedge laying is a traditional way to create a thick, bushy hedge from a thin and straggly line of plants. The stems are almost cut at the base, then laid horizontally. Stakes cut from side branches are knocked into the ground, and the stems woven between them. As the bushes regrow, branches come from the stems in all directions.
Coppicing is another traditional technique. Bushes are cut close to the stump, which encourages vigorous fresh growth. Several stems will grow from each stump, making the hedge much thicker.
However it’s achieved, a thick-based hedge with a long grass margin is excellent for nesting birds like yellowhammers and linnets.
Planting to fill gaps
One of the best things about hedges is that they are a continuous strip of natural habitat, which animals like mice and voles can move along safely. A gappy hedge doesn’t do this job so well, and it looks worse too.
You can solve this problem by planting new bushes in the gaps. It’s best to pick the same kinds of bush that are found in the hedge already. Native species are the best choice, especially the ones which provide flowers and berries for animals. They’re not only much better for wildlife but also just as colourful as ornamental shrubs.
The new bushes need lots of care to get going. Plastic guards protect them from rabbits and deer, which could otherwise eat them. It might seem strange not to plant large bushes, but small plants grow much more quickly, and survive better.
Why plant new hedgerows?
Hedges are natural corridors, linking habitats for wildlife. Planting a new hedgerow in the right place extends these vital links.
The choice of what to plant is really important. Native shrubs are best for wildlife, especially if they provide flowers and berries for animals. For example, hawthorn and blackthorn are very commonly found in hedges in southern England. Planting occasional trees like oaks along the hedgerow will make the habitat even more valuable as it develops.
The new bushes need lots of care to get going. Plastic guards protect them from rabbits and deer, which could otherwise eat them. It might seem strange not to plant large bushes, but small plants grow much more quickly, and survive better.
Another way to create habitat for wildlife along boundaries is to build dead hedges: barriers constructed from cut branches. These provide shelter for small animals like mice and are good for insects too. However, they are only appropriate on a small scale, not across a whole site.
Why manage a pond rather than leave it untouched?
Over a long period, it’s normal for a pond to fill up with silt and plant material. It will become overgrown and eventually disappear. Occasional work on the pond stops this happening, keeping the pond for people to enjoy in the future.
When it happens, this kind of work can look quite drastic. Trees around the pond may be reduced in size, plants on the banks cut back and heavy machinery brought in to remove material from the bottom of the pond.
The immediate outcome may not look good, but things will quickly grow back. The pond and its wildlife will benefit from the work for many years.
On the other hand, without management the pond could be lost entirely. Habitat loss is a major threat to species like the great crested newt, which depends on ponds. Great crested newts also need to be able to find food and shelter around the pond, and active management is important for this too.
Do ponds need to be managed every year?
No. A pond in good health doesn’t need regular attention. The plants and animals that use it go through natural annual cycles and as long as things remain in balance, the pond can be left to itself.
Pond management can change the habitats in a pond dramatically. Doing this occasionally is no problem, but if it happens too often it can have a negative effect on things living in and around the pond.
Over time, it’s normal for a pond to fill up with silt or dead plants, or for plants growing around the edge of the pond to start to take over the whole pond. That’s when it’s time to consider some work on the pond.
Clearing shading or encroaching vegetation
Ponds with lots of sunlight are much better for wildlife. The sun warms the water – especially the shallow water – helping plants, insects and amphibians thrive.
In an ideal situation, the vast majority of a pond’s edges would be open and sunny. Reducing the size of trees and bushes which surround the pond every few years helps keep sunlight reaching the pond.
As well as trees, ponds can have lots of long vegetation around their edges. This shades the edges and can slowly encroach into the pond. Ultimately, if the pond is shallow, it will be taken over completely. Occasional clearing stops this happening.
What happens if a pond dries out?
Some ponds naturally dry out during the summer, but this isn’t necessarily a problem. Many animals, like newts and beetles, actually benefit from their pond drying out.
This is because the drying reduces the number of predators in the pond, especially fish. It also exposes muddy areas, which are a valuable habitat for insects. The best kind of pond for wildlife is one with lots of very shallow water. Naturally, this kind of pond is more likely to dry out than a deeper one.
It might be tempting to refill or deepen ponds like this if they start to dry out, but it’s best to think very carefully first whether this is the right thing to do.
Managing silt or plant debris
Ponds fill up with silt and dead plant matter over time. This is a natural process, and many creatures in the pond live in this layer of material. However it can sometimes build up excessively and have a negative effect on water quality and life in the pond.
Clearing dead vegetation occasionally is one solution, but once a pond starts to fill with silt it’s a much bigger job to clear it. It’s such a dramatic event in the life of a pond that care is required.
The timing is important – working in the winter means fewer amphibians will be in the pond – and the silt should be piled away from the bank to avoid smothering special plants.
Changing the profile of the banks
Shallow margins are the best part of a pond for wildlife. A deep pond with steep banks can be greatly improved by changing its profile.
This usually involves scraping off soil next to the pond, widening the pond by creating a new shallow area along its edge. The wider and more undulating this area, the better.
Changing the shape of a pond is a big job which can have a big effect. It can be combined with other major pond works, like removing silt and introducing native plants.
Improving water quality
Excessive nutrients in a pond make it unbalanced, and less attractive to most wildlife. Signs of an overly nutrient rich pond include lots of algae, or murky dark water without any plants at all.
Nutrients reach the water in lots of ways, including in the water that feeds the pond and from leaves dropped by the trees above it.
One way to improve water quality is by planting reeds where water enters the pond. These act as a biological filter, trapping nutrients before they reach the pond. Reducing overhanging trees also helps.
Controlling invasive non-native species
There are several non-native pond plants which are sold at garden centres but can quickly take over and dominate a pond, reducing the amount of good habitat for native wildlife.
They can easily reach ponds by accident, and once there they can be really difficult to remove completely. Clearing the pond may have a short term effect, but it is almost impossible to find every piece of the plant. Sometimes the only solution is to dry out the pond and start again.
Prevention is the best approach – avoid introducing plants to ponds at all, and take great care if you do choose to.
Introducing native plants
After restoration, a pond might be lacking in vegetation, either in the water or around its banks. This is an opportunity to restock with native plants which are good for wildlife and pretty too.
It’s really important to be careful when introducing plants. If the wrong species finds its way into a pond it can cause major problems, and might be impossible to remove.
Why construct a pond?
Ponds are guaranteed to attract a wide variety of wildlife quickly. Pond construction is a really easy way to make a big difference for wildlife, whether or not there are already ponds at a site.
Ponds are valuable and declining habitats which support lots of important wildlife. Creating a pond gives you the opportunity to design it with wildlife in mind. This means lots of shallow water around the edge, with a long and undulating margin where animals will be able to find cover.
You’re digging a new pond in a park – isn’t it dangerous for children?
As well as being excellent for wildlife, ponds have tremendous potential for educating children about the wildlife that can be found on their doorstep. They can attract fascinating creatures like frogs and dragonflies, and provide an easily accessible link to the wonders of the natural world.
Of course any body of water is a potential danger to children, but ponds and lakes are a common feature in parks and nature reserves around Hertfordshire. The risk is extremely low with sensible supervision, and is greatly outweighed by the potential benefits.
Why shouldn’t I feed bread to the ducks?
Feeding the ducks seems like an innocent pastime. And yet there are actually many problems associated with it, both for the ducks and the wider environment.
It has been known for a long time that eating too much bread can make ducks ill. Using more natural food like oats or corn is much better for the health of the birds. But it’s the bread that the ducks don’t eat which can be an even bigger issue.
An accumulation of rotting bread at the bottom of a pond or river can encourage algae and bacteria, attract rats and spread disease. The algae also makes the water smell bad, and can slow any flow of the water. Faeces from the unnaturally large number of ducks just add to the problem. The gathering of ducks and people in a regular place can also cause erosion, damaging the banks of the pond or river.
Feeding the ducks has been a tradition of family days out for generations, and it’s unrealistic to think it will stop soon. But there are small changes you can make even while enjoying feeding the ducks, like reducing the amount you feed, giving them more natural food and avoiding feeding in the same place every time.
Why do we plant such small trees?
It might seem surprising, but the best way to establish new trees as quickly as possible is to use plants which are only around 60cm high.
This size of tree is much easier and cheaper to move and plant in a new location. It is also most likely to survive the process, and will grow more quickly than a larger tree.
Protocol for buying trees
Many pests and diseases are currently threatening trees in the UK. It is vital to take great care when planting trees to help protect Hertfordshire from these threats.
Tree planting is a common but preventable starting point for new pests and diseases. To minimise the risk, we recommend planting trees which have been grown in reputable UK nurseries from seeds sourced locally.
As well as protecting us from pests, this makes them easier to establish. Trees planted in the same area they came from are more likely to grow successfully.
The best possible source for trees is from the woodland where planting will take place. In the example above, seeds were collected nearby and grown in a nursery before the saplings were returned to Bencroft Wood for planting.
The right species in the right place
Native trees are the best choice for wildlife in any location. The benefits they offer wildlife are far greater than trees which don’t naturally grow here, and they can be just as pretty.
In natural woodlands, only native trees should ever be planted. These support more insects and everything else in the wood, like birds and bats, benefits as a result. They are also more likely to grow successfully.
Some tree species are currently threatened by new pests and diseases. In places where dead or dying trees could pose a future safety risk, it is more sensible to plant trees without any known threats.
There are many places that aren’t right for tree planting at all. The value of what is there already, as an open space or a special place for wildlife, can easily be greater than what could be achieved by planting trees.
Establishing trees successfully
Young trees are very vulnerable for a few years, until they have grown enough to withstand being eaten and can compete with the plants around them.
Tree guards, which are plastic tubes fixed around the trunks, protect the trees from grazing animals like deer or rabbits. They are simple, cheap and effective, but they do need to be remembered – they should be removed after a few years once they have done their job.
Time spent keeping the area around the tree weed-free as it establishes itself is also a good investment. This means the tree doesn’t have to compete for water or nutrients.
Why do you plant trees in straight lines?
Planting in straight lines makes the future management of a woodland much more efficient, and gives all the trees the best possible chance of survival.
Planted trees need lots of aftercare to establish successfully. One important job is controlling plants around them to reduce competition. Gaps of a regular size between trees make mowing around them far easier. Then when it is time to cut down some of the trees, the gaps allow larger machinery space to get into the woodland.
Equal spacing also means every tree has equal access to light, nutrients and water. This is vital in balancing competition between trees, achieving good survival and success across the plantation.
This design may look unnatural to start with, but as the trees develop and some start to be felled, the lines get less obvious.
Why do you plant so many trees then come back and cut half of them down later?
Planting trees close together makes them grow straighter and taller, as they’re competing for light with their neighbours. This is done in the expectation that around 20 years later many of the weaker trees will need to be felled.
The trees which are cut down have served a valuable purpose, improving the quality of those that remain. They can also be used, for example as fire wood. This process of thinning continues as the wood matures, eventually leaving only a small proportion of the trees which were originally planted.
Why do we sometimes leave debris in the river, or add debris to the river?
Woody debris has lots of benefits, both to the river and the wildlife that lives in it. Leaving it where it falls, or even adding it artificially, is a great idea, as long as there’s no risk it could cause flooding or erosion.
Historically all wood that had fallen into watercourses was removed, because it might look unsightly, or because of the risk of it causing flooding or erosion. However, it’s much better to consider each piece individually – often the advantages of leaving it where it is outweigh the risks.
Woody debris provides habitat for fish and insects, can help reduce erosion of river banks and creates more variety in the flow and the depth of the river. It’s so valuable that we sometimes create it artificially in well-chosen locations, to improve the flow in rivers which have become too wide.
Improving the health of a river doesn’t just help things at the bottom of the food chain. The benefits are passed on to larger fish, and to the top predator in our rivers, the otter, which is making a comeback after decades of decline.
Will the debris left or installed in the river make it more likely to flood?
Whether woody debris has fallen into a river naturally or been installed there intentionally, it is assessed in the same way to ensure it doesn’t increase the risk of flooding.
In some places, there’s a risk that it will cause blockages beneath bridges or in culverts and increase the chance of flooding. If this risk is too high, the debris will be removed.
In other locations, woody debris can actually reduce the risk of flooding in built up areas, by helping to encourage the storage of flood water upstream. When flood plains work as they should, this helps reduce flood risk elsewhere.
Re-naturalising a channel
The course of many rivers has been artificially modified, making them very different to their natural state. This affects the way the water flows, and the amount of vegetation along the banks.
There are different ways to improve habitat in a river like this. Most simply, using pre-planted rolls of matting attached to the banks, vegetation can get established even next to steep artificial banks.
You can also restore the original channel by recreating the natural course. It’s a big job, but once successful the flow of the river and the shape of its banks will be much more natural. Everything about the new course can be designed for wildlife, and a river flowing naturally looks much better too. If well planned, there’s no reason the risk of flooding should increase.
Reducing shading vegetation
Just like a pond, a river is healthier when sunlight reaches the water and the river banks. Especially when the river is narrow, trees along the banks can create a dark tunnel which suppresses the life beneath.
Reducing those trees, maybe by traditional management like coppicing, lets extra light through. More plants will grow along the banks and in the river, and insects will increase thanks to the extra plants.
The bankside vegetation is also good for special animals like water voles. Even the river benefits as its banks are stabilised and can recover their normal width.
Grazing animals by the river
If there are too many animals in fields along a river bank, it’s bad for the river. The bank gets eroded and the river becomes muddy and excessively wide.
On the other hand, having animals by the river is no bad thing. They control plant growth and create bare ground, which is good for wildlife. The important thing is to get the balance right – keep an eye on the site and move the livestock if needed.
Just like any wet place, ditches are really important for wildlife. They can also play a role in filtering out pollution before it reaches rivers.
The best way to manage ditches is by clearing plants and silt when they build up. This can be quite destructive for the wildlife living in the ditch. It’s best only to clear sections of the ditch each year. This gives animals a chance to find refuge, and means the ditch keeps performing its filtering role too.
When clearing ditches, there’s also an opportunity to do more. Deep ditches with steep banks have few attractions for the many creatures that thrive in shallow water. Changing the shape of the banks, by creating a broad, shallow slope on one side, makes the ditch much more attractive to wildlife.
Buffer strips along watercourses
Stopping pollution reaching our rivers is valuable for everything that lives in them. Strips of long grass along ditches or streams help to filter things out before they get to the water.
Problems include eroded soil and the chemicals found in fertilisers. They all do much less damage if they can be kept from our water courses.
Buffer strips are also great habitat for wildlife, creating cover for animals which like living along the water’s edge like water voles.
Control of invasive non-native species
Some plants which don’t originally come from this country have invaded our rivers and streams, damaging native wildlife. One of the biggest problems is Himalayan balsam.
Himalayan balsam is an attractive plant with pink flowers, but can do real damage to our river habitats. It’s found especially along river banks, and its seeds are spread along rivers by the flow. It grows so strongly and densely that it shades out other plants, killing them off and becoming dominant. It can be controlled by pulling or cutting before it sets seed, but it’s very hard to remove completely.
Why cut trees down?
There are lots of reasons to cut down trees. Often the idea is to improve the woodland in the long term, but sometimes trees are removed to return the site to how it used to be.
Many places in Hertfordshire have a long history without trees. These places can be really important for wildlife which depends on grassland to survive, but many have been lost along with traditional grazing.
Often it is surprising how recently trees have colonised a place. When you cut down the trees and restore traditional management, the plants and animals that used to be found on the site can quickly return.
This is what CMS is doing at Broxbourne Wood. An area with dense planted conifers and natural regrowth is being progressively cleared to restore traditional wood pasture, where cattle can graze beneath scattered trees.
Why manage woodland rather than leave it untouched?
Woodlands in Hertfordshire have a long history of management by people, and only small fragments of what once existed remain.
Active management is the only way to maintain a variety of habitats in our small woodlands, and to help restore woods where huge changes have taken place in the last 50 years.
Forests once covered much of the UK. Natural events like storms would have created a wide range of habitats – open spaces, young, mature and dead trees. Wildlife could move through the forest to find whatever habitat it needed. In the small woods we have left, that isn’t possible.
If we want to support the widest possible range of wildlife, our only choice is to artificially create a range of woodland habitats at every site. This means the same small woodland can support bats roosting in holes in old trees, moths living in the canopy of mature trees, birds feeding on the caterpillars of these moths and nesting in dense scrub along the edge of sunny rides and wild flowers growing along the paths that run through these rides.
In many woods, trees grow too closely together. This isn’t good for their development. Cutting down some of trees helps the ones that remain to mature properly.
In a wood where the trees are too dense, little light reaches the ground, and the wood looks dark and uninviting. Competition for resources makes the trees tall and spindly.
Removing a selection of less healthy trees gives those that remain space to grow. It also allows light into the wood, creating a new opportunity for plants on the ground like bluebells. A healthier wood with more variety should be the result.
One of many woodlands where thinning can make a difference is Bentsley Spinney in St. Albans. CMS has helped put together a management plan there which will involve thinning an area of dense sycamores. Not only will this help the trees that remain, but it will also create an opportunity to plant new native trees.
Open space and fresh growth in woodland is hugely valuable for wildlife. Felling creates this open space, and makes room for young trees to grow.
Many plants and animals live towards the woodland edge, which offers more light and more opportunities. Cutting down trees creates much more of this special woodland edge habitat.
Newly cleared areas are also good for young trees. Well-balanced woodland has trees of all ages, but many of our woods are much more uniform in age. Cutting down some trees and allowing new saplings to grow helps recreate a more natural age structure.
In woods which have been planted in the past, for example with conifers, felling is an opportunity to restore natural woodland types. A range of native broad-leaved trees can be planted in the space created.
Fixed point photography of felling work in Broxbourne Wood.
Why are there stacks of timber in the woods?
Stacks of timber are the product of woodland management work such as thinning. This is only temporary storage before the timber is taken to be processed. Selling this timber helps fund management which keeps the wood healthy.
Once trees have been felled, sometimes it is enough to leave an area to grow back naturally.
New trees grow from seeds which are already in the soil. If they’re species that grow naturally in the area, this is the best way to restock native woodland.
Natural saplings can be protected and encouraged. As the young wood matures, the number of trees should be reduced to favour the strongest. This gives each tree enough space to grow even more strongly.
A healthy woodland needs a mixture of trees of all ages. If trees aren’t growing naturally from seed, or if there is a chance to improve the woodland by introducing native trees, planting new trees is a good option.
Planting is only possible where space has been created. Young trees need lots of light, so they won’t grow under existing trees. In fact a space at least twice as wide as the height of the surrounding trees should be made for planting.
To achieve most for wildlife, it is best to choose tree species which grow naturally in the area. These support more insects and everything else in the wood, like birds and bats, benefits as a result. They are also more likely to grow successfully.
Opening up glades and rides
Many woods don’t have much open space, where sunlight can reach the ground. Open spaces within woodlands are fantastic habitat for flowers and butterflies. Bringing back existing tracks increases the amount of open space in a wood and helps wildlife thrive.
Woodland tracks have often become overgrown as woods stopped being managed commercially. But they do still exist, and felling trees along their edges to restore them is an easy way to have a high impact for wildlife.
Restoring rides at Broxbourne Wood had immediate benefits. The new woodland edges were bathed in sunlight, encouraging plants to grow. Silver-washed fritillaries responded immediately, becoming a common sight along the rides in mid-summer.
This work also creates lovely walking routes, which can be full of life. Developing a good network of rides is a great way to help people enjoy a woodland.
Coppicing and pollarding
Many woodlands managed traditionally through coppicing have fallen into neglect, as the market for their products disappeared. Restoring this traditional management is an excellent way to improve woodlands for wildlife.
In a coppiced wood, trees are repeatedly cut at their base. This encourages strong new growth with lots of shoots, which can be harvested once they are old enough to use. Usually the coppiced trees are mixed with ‘standards’ – scattered full-grown trees which allow enough light to reach the coppice. These standards would have been left to grow for 100-200 years before being used for timber for buildings.
In Hertfordshire, the normal tree used in coppices is hornbeam, with oak standards. Its original use was for charcoal, which was in great demand in 19th century London, but it’s now starting to regain its value as firewood. It’s slow-growing, which means it can only be cut once every 20 years.
Coppicing is so good for wildlife because it results in woodlands with trees of many ages. This variety creates habitat for threatened species like the dormouse. Flowers benefit from the sunlight reaching the ground after cutting, and birds can nest in the thick regrowth a few years later. Older coppice and mature standard trees complete the picture.
CMS has begun the process of restoring coppicing to Bencroft Wood. A small area of old hornbeam coppice was cut and, several years later, is growing back strongly, bringing fantastic new variety to the woods.
Pollarding is slightly different – trees are cut higher up the trunk but then grow back in the same way, with lots of small shoots. This stops grazing animals eating the regrowth. Because it extends the life of a tree and promotes new growth, it means the same tree can be many things for wildlife – old dead wood and thick young growth at the same time. In an urban setting, it’s a good way of keeping trees at a controlled height.
Dealing with deer
The abundance of deer in the Hertfordshire countryside makes management of our woods more difficult. Their grazing limits plants on the woodland floor, and makes it hard for young trees to grow.
The most effective way to control this in Hertfordshire’s busy woodlands is to physically prevent deer from grazing plants, either individually or across larger areas.
Tree guards, which are plastic tubes fixed around the trunks, protect trees from grazing animals. They are simple, cheap and effective, but they do need to be remembered – they should be removed after a few years once they have done their job.
Fencing makes a difference in larger areas, like after coppicing a block of woodland. When deer are excluded from a piece of woodland, it can make a huge difference to plants growing there.
Dead wood and old trees
When trees die, they don’t stop being part of the woodland environment. In fact dead wood is hugely important for a whole range of wildlife.
The best way to deal with dead trees is to leave them where they are, whether standing or on the ground, as long as they pose no great danger. Building piles of dead wood also creates a great opportunity for wildlife.
All sorts of creatures use dead wood – birds, bats, beetles and mushrooms to name just a few.
Why have you cut down healthy trees and left dead ones?
A healthy woodland needs both living and dead trees to support a full range of wildlife. Standing dead trees and dead wood on the ground are good for different things, so it’s good to have both. This means that if a dead tree is in a safe place, away from paths, it’s much better to leave it.
On the other hand, there can be good reasons to cut down healthy trees. This could be to help stronger trees develop, or to bring more light to the woodland floor, helping plants on the ground.
Can I help myself to fallen wood rather than let it go to waste?
No. As long as it is safe to do so, we leave dead wood on the woodland floor because it benefits wildlife. This wood is the property of the owner of the woodland, so removing it is actually theft.
Is ivy on trees a problem?
Many people think ivy damages trees, but this isn’t the case. In fact it’s a climbing plant, using trees for support and nothing more. It provides excellent habitat for birds and insects, and it’s a great thing to have in a woodland.
Its flowers provide a very late nectar source for struggling UK bees, and it produces berries later than other plants too. An added bonus is that it keeps its leaves through the winter, providing a splash of colour in otherwise bare woods.
Heavy growth of ivy is likely to be a symptom, not a cause, of a decline in health of a tree. Ivy does compete with the tree for resources, but a healthy tree won’t allow enough light through for the ivy to dominate.
Control of invasive non-native species
Some plants which don’t originally come from this country have invaded our woodlands, damaging native wildlife.
One of the most common and most problematic is rhododendron. It forms dense thickets which smother other plants, and poisons the ground with toxic chemicals from its roots. Eventually there is nothing left but the rhododendron and the trees above it. Removing it, and then preventing it from returning, will help wildlife in the wood.
Sycamore is very common in our woodlands. But it isn’t a native tree, and it supports a much lower variety of wildlife than other trees. Selectively felling sycamores and replacing them with other species can be a good idea in some situations.