Community Woodland Network.

Is natural regeneration the best method for woodland creation?

Why plant? Additional thoughts…
 Gaps in woodland / habitats tend to be filled by planting (though natural regeneration will happen with time)
 There is a historical element to planting (i.e. it has taken place in the past and we are in the mind set of planting)
 Limited planting may take place to make a regimented wood more varied visually
 To interfere with the species mix e.g. where we may prefer not to have a woodland dominated by particular species
 Replacing unwanted species that die with other species to stop those unwanted regenerating
 Planting can create a border to an area of natural regeneration, providing a new habitat such as a hedgerow
 Community involvement and getting youngsters involved for the future of our environment is an important consideration (we need to consider other ways to engage communities in addition to tree planting)
 Current grant structure encourages planting

Natural regeneration. Additional thoughts…..
 The seed crop of the trees is important for future species mix
 Ensures that trees can cope with climate change
 Consider that some habitats are important without planting (e.g. wetlands, grasslands) – it is inappropriate to plant in some habitats
 Archaeological sites can be lost by planting (also consider the historical use of the land and the feelings of the local community e.g. has it always been a grass meadow and is it loved as such)
 Allows trees to grow more openly and more likely to resist strong winds etc

Important considerations
 What is the objective for your woodland (e.g. is timber, community involvement or biodiversity your top priority)
 Consider long term objectives and views
 Need careful understanding of individual sites
 Need for the public to be educated that natural regeneration can be an active process
 Trees are only one aspect of woodland creation
 Need to change people’s perception of a “neat & tidy” woodland
 We are generally impatient and there is a perception that woodland cant manage without us
 Look at the past and research what your wood / site was like – you may be able to learn from this

Natural regeneration. Some issues…..
 Patience is a virtue! (However it may happen quicker than you think)
 Trees will find it harder to naturally regenerate on arable and improved land
 Trees can regenerate on very poor sites as there is no competition
 Fungi plays an important role in accessible tree nutrients & therefore in natural regeneration.
 Is your site going to regenerate? There does need to be a seed source at a reasonable distance though birds will help in distributing seed further
 It doesn’t necessarily happen on all sites – it is site specific
 Need to have confidence that it will happen in order to be patient
Note: more education / papers is needed on this and the WT hopes to provide some papers on this subject in the future
 Grazing can play an important role

Workshop handout:
(I assume we accept that creating more woodland is a “good thing”.)

Some general introductory thoughts

If a field were left to its own devices, or if humans suddenly ceased to exist, the inevitable result in much of lowland Britain would be woodland after only a few decades.

Some examples of natural regen;
Grizedale Forest (Lake District) – the Forestry Commission is allowing nature to return felled conifer plantations to native woodland.

Old railway lines quickly become overgrown, requiring continuous maintenance where they have become footpaths/bridle ways/ cycle tracks.

The Caledonian Forest is being allowed to extend itself naturally by the RSPB and others.

In Surrey, Woodland Trust sites Edolph’s Copse and Glover’s Wood contained substantial areas of fields in 1840 (Tithe Map). These were abandoned and have become wooded.

Abandoned land can change from open ground to woodland in only part of a lifetime. A flower-rich meadow at Edolph’s only exists because of management to prevent trees spreading in.

• Too many people, especially in councils and some businesses, think there is something clever about planting trees in existing woodland where natural regen is taking place (and often where their plantings are too shaded by existing trees).

• Tree planting is often done using non-native or non local plants, which can have significant consequences for native wildlife.

• Ancient Semi-Natural Woodland is defined as land with woodland cover for at least 400 years. In 400 years from now, how much difference would there be between a wood planted now and one established naturally?

• Initially, secondary woodland may be limited in the number of tree species it contains – depending on existing neighbouring species. In time, other species will spread.

• An impressive 30 or so completely natural Wild Service saplings are scattered through the 28 ha. Hammond’s Copse, Surrey – a wood cleared and planted with conifers 30 years ago, now being restored by the WT.

• Research has established that trees grown from local (possibly within just 5 miles depending on local conditions) seed will establish most successfully.

• At the July 2003 CWN conference, Richard Smithers gave a very interesting talk on “Woodland Biodiversity”, and I thought he said his researches had shown that natural regen produced better trees?

• The Woodland Trust has a figure for the cost of planting a tree [is it £10?] – the cost of planting a significant area can be astronomical – but free with Nature!

Why interfere with Nature
Nature provides a complete self-sustaining system that has worked for millions of years and can continue to work. Human “management” or “interference” does not necessarily work or last. In nature reserve situations, “management” can be defined as, “action taken to prevent Nature behaving naturally”. Management is undertaken because natural processes need large areas together with large herbivores (and their predators) for a sustainable ecosystem to flourish – minimum 500 ha, preferably much larger, such as are being created in Holland – Oostvaardersplassen, etc.(several areas of 5000 to 7000 ha and to be linked).

What reasons are there for creating woods
• To provide wildlife habitat
• To enhance the landscape (though trees can obscure views)
• As shelter belts
• To hide buildings, car parks, etc.
• To produce timber/wood/biomass
• To remove carbon from the atmosphere
• Because it seems like a good idea

Why plant rather than allow natural processes
• Commercial reasons – to get quick return (should not apply to delegates to this conference?)
• Impatience – planting a wood is culturally popular and modern people expect to see results immediately in everything – should this unnatural and unsustainable attitude be pandered to?
• Special types of planting – hedges especially or to establish coppice areas – not natural and veering towards commercialism, but could be appropriate for less wooded areas of the country. Hedges have considerable wildlife value, but shaws or rews could be better.
• To ensure less common species are represented (but in areas where they naturally grow)
• Very small or isolated sites where natural growth may be especially slow and produce minimal diversity

Pros and cons of planting or natural growth (in no particular order)
It depends on your point of view as to whether some of these are advantages or disadvantages!
Even professionals have planted certain species on soil types that are inappropriate
Most native trees support far more other species, such as insects and lichens, than trees introduced by man.
Natural growth advantages
No cost
No pollution or waste materials
Guaranteed local origin of seed
A mix of species (not separate blocks)
Random spacing of trees
Ecotones will develop
Natural genetic variety is encouraged
Bushy trees with plenty of side branches are likely to occur, providing more habitats
Greater chance of specimen trees developing
Trees establish better and are more strongly rooted into ground
Saplings less likely to attract vandals Natural growth disadvantages
Slower to establish
May be limited variety of species for first couple of centuries
Trees may not produce “good quality” timber (does this matter – the British Empire was founded on ships made from curvy Oak – who knows what might be useful in future?)
Land purchase grants may require active management/planting – grant-givers need educating!

Planting advantages
Speed of woodland creation
Can encourage public interest and support for woods and wildlife (but how long does this last?)
Can ensure variety of species
Gives control over what grows (surely this is a disadvantage) Planting disadvantages
Cost
Often need to obtain grants with expensive and time consuming bureaucracy
Rigid spacing and excessive numbers of trees – often forced by grants
There is rarely an opportunity for specimen trees with plenty of space around them
Use of plastic tree guards/shelters
Use of vehicles with attendant pollution, etc. by contractors or public
Uncertain origin of trees – DNA tests imply that some “plant passports” may be unreliable as well as polluting in themselves
Usually single species blocks of trees
Often limited number of species
Often rigid edges to wood, ecotone ignored
Genetic modification is practised by selecting straighter, taller and faster growing trees
Planting fosters the idea that woods can only result from planting
Tree shelters may attract vandalism, especially in urban areas (NB Tooting Bec Common, LB Wandsworth)
Chemical and other weeding around trees often practised – more pollution (vehicles / containers / equipment) and can disadvantage other species
Chemical weeding sometimes targets naturally growing shrubs/trees
Tree shelters have to be disposed of
Trees may not root strongly into ground
Possible weather problems – frost/drought when planting, drought over next 2/3 years
Transplanting deep rooted tree such as Oak is likely to slow the tree’s development – it is said that the whole life of a plant is influenced by the way it grows when young

Nature informing what and how to plant if planting decided upon
• Always use species which would naturally occur in the area (natural being those which have colonised since the last Ice Age)
• Nature starts by planting Birch to give shelter to slower growing trees. Birch also grows fast giving the appearance of a wood fairly soon.
• In completely natural woods, different tree species are all mixed up, not in blocks of one species
• Planting locally collected seeds, nuts, fruit, berries is an alternative to planting saplings. It is cheaper, but there is nothing to show for the work involved immediately it is finished.
• One option could be minimal planting of some less common species and scattered groups of Birch. In some areas Birch saplings may be obtained free as they are considered an invasive weed.
• Another option is to just plant in areas remote from existing trees, and let nature gradually fill in the gaps.
• The edges of a naturally developed wood will have an ecotone where trees gradually thin out towards adjacent open land, rather than having a hard edge. This should also be allowed for in the vertical plane by planting shrubs at wood edges.
• For Oaks to develop fully into rounded trees, they need plenty of room and should be planted at 35 metre spacing (note the coppice with standards system tends to achieve this automatically).
• Open areas should be left within woods (sheltered glades are valuable sun-traps for many species), all with ecotones. Note east-west aligned glades will have a long north edge receiving sun for the longest time. The woodland edge is often considered to be an important habitat, erratically shaped glades can increase this significantly.

Management to control invasive aliens
Even if leaving land to Nature, Man’s negative influence may need counteracting. Certain introduced invasive species such as Rhododendron and Japanese Knotweed quickly dominate land given the opportunity and should be rigorously controlled as soon as first seen. If regarded as an interesting novelty initially, they are likely to become firmly established requiring much more work than if tackled early. Rhododendron is a particular concern as a host of various species of Phytophthora fungus newly arriving in England, potentially harming native Oaks, etc.
Rabbits, Deer and Grey Squirrels can be a problem in places, but rarely prevent natural tree growth on a large scale. If they do keep small areas open, this provides an excellent habitat to maximise biodiversity in the absence of large herbivores.

Not just trees
All large organisms depend on the smallest ones. A healthy wood will have a vast range of species. In situations where it is considered desirable to plant trees, it may be worth considering planting (or scattering seeds) of native herbaceous plants, as well as bringing in dead timber (only from nearby).
As the Woodland Trust have been doing for years, remember that other habitats within woodland are important – ponds and open areas will all be sun traps and excellent for insects.
Don’t plant trees where other threatened habitats exist!

Some possible questions which may be asked
• How long does natural tree growth take? – Answer: compared to the life of trees there is little difference to planting – slower to start, but may then be faster growing. Comparisons depend on size of trees planted. Natural growth would obviously take longer to spread over a large area, but if Birch nearby, this can spread fast.
• What do you do if no trees are appearing? – Answer: be patient!
• With global warming do we need to grow trees quickly to remove carbon from the atmosphere? - Answer: the slightly slower establishment of natural woodland is totally dwarfed by the amount of fossil fuels being burnt and global woodland destruction. Almost all plants, not just trees, absorb carbon. Money saved by not planting trees could be used to make more land available for natural woodland development.
• With global warming should we be planting “Mediterranean” species? – Answer: if global warming causes melting polar ice to cut off the Gulf Stream, British temperatures could well decline rapidly by 15º C, so it is best to carry on with trees which are growing here now.

Back to the top