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| . Field Layer
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Introduction . Woodlands are conveniently divided into 4 vertical layers or zones. They are, in descending order of height: canopy layer (i.e. Trees); shrub layer (i.e. large shrubs: hazel, hawthorn, etc.); field layer (herbaceous plants, grasses); ground layer (moss, algae, fungi, etc.).
This section deals with the problems involved with managing the Field Layer of a new woodland plantation
Managing Light Levels .
The main factor influencing the structure of a typical woodland fieldlayer plant community is the amount of light (or lack of it) that reaches the ground. In established deciduous woodlands, plants tend to flower in the spring before the canopy- and shrub layer trees have come into leaf. After this time the amount of light getting to the ground is dramatically reduced: preventing the more invasive (and light demanding) grasses and weeds from establishing. In a semi-natural woodland where the soil has been relatively undisturbed for centuries, both the field- and ground layer plant communities appear stable. Although even in these woodlands, where coppicing is undertaken the increase in light levels, resulting from gaps in the canopy- and shrub layers, means that remedial management to control weeds such as thistles and brambles is necessary. Where a plantations have been established with the intention of producing a timber crop, the normal practice is to plant as densely as possible and to keep the amount of forest edge to a minimum. This allows the deep shade of the canopy to naturally kill off most of the the arable weeds. After a few years, a more natural woodland plant community can be established by seeding, or planting, shade tolerant species.
Arable Cultivation . In an ex-arable site, such as ours, the plant communities that characterise the field- and ground layersof an established woodland are not thought to be present. In the past they appear to have re-colonised naturally only after a period of several hundred years, e.g. Ironbridge (Shropshire) and in the Forest of Dean. When we originally bought the site it had been in permanent cultivation for many years. This had left a highly enriched and disturbed planting medium. Within the soil there existed a seed bank of farmland grasses, fodder crops and arable weeds. Around the perimeter of the site, in the hedgerows and verges, an array of invasive weed species were awaiting their opportunity to colonise a new area. There is a view among ecologists that tree planting is a waste of time as it cannot succeed due to the absence of the necessary fungi from the soil. However this does not seem to be the case: as our trees are all thriving. In fact our experience is that trees and shrubs thrive on this sort of land, provided that the basic principles of planting and aftercare are followed. As it is not possible to see what is happening below the ground we can only infer that either a) the fungi are actually present in some form or b) the fungi are not actually essential.
Invasive Arable Weed Species . The high light levels associated with new plantations, together with the clearings created as a result of the coppice cycle, has only compounded our difficulties in managing our field layer vegetation. Hazel, for example,has a dense canopy which allows very little light through to the ground. However, if coppiced by clear-cutting to ground-level, no sooner has the canopy closed than we cut it down: revealing a nice bare patch of earth for the nettles, thistles and cleavers to invade. Experimenting with different coppice management systems has allowed us to minimise this problem. The Coppice-with-standards system and the practice of only partially cutting the hazel crowns allows light-levels to be managed well enough to control all of the following weeds except for Bramble. Stinging Nettles We have huge swathes of stinging nettle. But as these are very beneficial to many types of butterfly, and of no threat to the new shoots, we tend to leave them alone. Now that the plantation has established, stinging nettles are no longer a problem. In previous years, when they were growing among young coppice regrowth and Cleavers(see below) was growing through them, I used to beat the nettles down with a stick and then spray them with a broadleaved weedkiller (e.g. Relay Turf) whilst they were flattened against the grass. Thistles We have at least 3 types of thistle: Spear Thistle Creeping Thistle Smooth Sow Thistle
Once again thistles are very beneficial to butterflies, Goldfinches and insects so I am reluctant to overmanage them. I only spray them with a broadleaf weedkiller (e.g. Relay Turf) when they are growing amongst cleavers. However they do need some management or they will completely take over. Spear Thistles,particularly, tend to rip one to pieces when trying to work in the wood. My normal approach is to wait until the seedheads are starting to form and then cut them off with secateurs and, at the same time, carefully spraying the plant with a broadleaf weedkiller. Unless the thistle is either removed or killed it will simply produce new flowers and, eventually, more seeds.Pulling out thistles is not really a practical option (1 man:1 million thistles) and I dare not spray to close to anything that I don't want to kill (hazel for example), so I let the insects enjoy the flowers and try to keep the cuts and scratches to a manageable level. Cleavers This is a weed of arable cultivation. In farm crops it scrambles up the stems and smothers the crop. It does the same thing to newly coppiced trees. It cannot be pulled out by hand as the stems are very brittle and snap off near the ground: allowing the roots to regrow. Each plant will bear up to 2,000 seeds. These seeds can lie dormant for up to 3 years. Cleavers will be suppressed when canopy closure has occurred. Careful management of light levels within an established coppice woodland will remove the need for chemical spraying. If spraying becomes necessary then proceed as follows: early as possible, once it has set seed then the battle is lost for another year. can be sprayed without getting weedkiller onto he leaves of the tree/shrub. Cleavers likes to grow over things: like young hazel seedlings. Often, I only spot the hazel after I have deluged both it, and the cleavers, with weedkiller. Keeping a barrel of fresh water close by lets me wash off the weedkiller before it can do any harm. Fortunately Cleavers has a much shorter growing season than Hazel: it is really only a problem from May until mid-July and the Hazel can usually cope. Teasel This is a very pretty, architectural, biennial weed of damp grassland. It is thriving at the bottom of our, very slightly, sloping meadow area. It doesn't get in the way of my work and does no apparent damage to the coppice regrowth. It produces rosettes of spine-coated leaves in the first year. By the second year, conical heads of purple flowers are appear on very tall, angled and spined stems. They are very popular with bees and Small Skipper Butterflies in July-August; and with finches, particularly Goldfinches, over the following winter. When all of the wildlife have had their fill, I cut them down; rub-off the spines with fine sand-paper, spray them with gold and silver paint; and use them as Christmas decorations. All in all, hardly a weed at all. Bramble (Rubus fruiticosa) After 10 years or so of management, bramble has taken over as my number one enemy. The first job when starting coppicing each year is to cut down the bramble in the section to be worked. It often hangs amongst the trees like old Christmas decorations and its shoots lurk among the other vegetation to trip one over. Unless care is taken gloves and clothing get ripped to shreds. I cut the bramble back to 5 or 6 inches in the autumn; the last coppice job in spring is to spray weedkiller onto the newly emergent leaves. This technique works well on the bramble but I never manage to get every bit and birds keep dropping new seeds everywhere.
Introducing Meadow Species . Because we have a high proportion of open pasture or newly coppiced scrub, we have opted for encouraging meadow species instead. We are doing this by creating small islands of plants which we are able to cultivate and which will, hopefully, disperse their seed into the surrounding areas. We also encourage existing species where we find them. Inroduced plants include: Ragged Robin Lady's Smock Foxglove Bluebell Corn Chamomile Jacob's Ladder Hawkbits Knapweeds Campions.
Existing plants include: Clovers (white, red) coltsfoot white dead-nettle
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