Furzefield Nature Reserve totals around seven hectares and consists of two different habitat areas: Furzefield Wood and a small meadow called Halfpenny Bottom which is located by the side of Potters Bar Brook...
In the jargon, the wood is called Coppice-with-Standards which means that is simply an area of woodland containing extensive Hazel and Hornbeam or Chestnut*, which is cropped regularly, interspersed with large individual trees or standards which are occasionally felled. Coppice-with-standards as opposed to the other basic types of woods (High Forest and Forest-cum-Pasture) is the best type of woodland to have for plant and animal diversity because its very management keeps the woodland habitat dynamic.
The reason for this higher diversity of species is the coppicing of the wood. Managed coppice woodland is split into specific areas called coupes where the wood is harvested annually in a cycle. During the coppicing, the coupes change from closed to open canopy over the years and this enables a different variety of plants, and then insect and animal life, to thrive according to their specific needs. Thus, in a coppiced wood that contains many coupes (generally 10-15) there are always places with varying amounts of re-growth, light levels, ground cover and debris providing a high diversity of habitat for associated species.
The standards, or large trees, in Furzefield are mostly Oak and Ash with Silver Birch and Hornbeam as well. The oaks have a noticeably long bole, or trunk; this is normal in coppiced woods and follows close planting. The oaks seem to be a mixture or hybrid of the two most common varieties, the English Oak (Quercus robur) and the Sessile Oak (Quercus petrea). The ash is the Common Ash (Fraximus excelsior).
The Coppice Cycle
Furzefield Wood is actually divided into 7 coupes or compartments (A - G) for coppicing, this means there will probably be a very short 7 year cycle, I dont know. Each year then, one area of the wood is coppiced preferably next to a coupe that was coppiced the previous year. In this way, the migration of plant and animal life between adjacent areas is made easier and there follows a diversity of habitat. Unfortunately, this isnt always appealing to the public eye (large swathes of woods apparently decimated!) so sub-adjacent coupes are often cut instead, hopefully liked by rides or pathways, natural or otherwise.
The harvested wood is separated into brash and cordwood. The cordwood is the larger pieces of timber cut from the tree; the brash is the small twigs and leaves stripped from the cordwood. The cordwood is arranged into cords, i.e. neat piles of wood ~8 feet by ~4 feet by ~4 feet high. (1 cord = 128 cu.ft.) The brash, or trimmings, are either burnt or left as debris on the woodland floor to decay and provide a habitat for fungi and insects.
After cutting, a coupe will show a rapid re-growth the next year as new shoots develop from the stools or stumps of the coppice trees, these shoots are called wands and can grow over three metres long during the year. The cutting of the cordwood allows more light into the wood and there should follow a flowering of the woodland plants long dormant in the shade. As the years pass the wands grow thicker and more flora and fauna will take their position in this new habitat as conditions favour them the wood will diversify. At the end of the coppice cycle the lower canopy will be well developed and ground flora will have diminished along with the light level. And so the cycle continues.
Coppice cycles can be short (10-15 years) or longer (15-20 years) depending on the value of cordwood size. In Furzefield I do not believe the cordwood has any market value since it is left where it is cut, although the smaller wands are taken. Traditionally, cordwood would have been used for firewood, charcoal production or garden use.
The number of standards or large trees is often limited to 15 or 20 per hectare to maintain a good high canopy; it follows therefore that some mature trees may have to be felled from time to time. Dead trees still standing and safe can be left for many birds, insects and fungi can make use of them.
The meadow seems to have been a used for pasture or meadow for at least 400 years seemingly according to the Trewell map of 1594 (locate map). The map shows the area by Potters Bar Brook as the Longe Pightell an enclosed field. Of the three general types of grassland (Acidic, Calcareous and Neutral) the meadow would be considered as neutral, the soil being mostly clay rather than peaty or chalk-based.
The meadow contains a large variety of wildflowers, or forbs, and the art is to conserve the meadow for wildflowers rather than grass because Halfpenny Bottom is not used for haymaking. If it were not for the grazing which goes on by wild rabbits (yes, it has to be taken into account) and the annual cutting by Council contractors then Halfpenny bottom would naturally revert to scrub and then, eventually, woodland. You can see this effect already starting with the steady encroachment of the Hawthorn, Blackthorn and Elder bushes on either side of the meadow.
Choices have to be made considering the annual cut of the meadow. Cutting early (late May/early June) means that many late flowering forbs will not have set seed so early flowering plants will be promoted in the following year. Early cutting will also mean that many insect species will not have finished their life cycles and so reduce bio-diversity.
Late cutting (July/August) on the other hand will promote coarser grasses and encourage late flowering plants. Invertebrates will have had longer to complete their complex life cycles too. Varying the time of the annual cut may not have any real benefit; although splitting the meadow in two and treating both halves differently could be a solution for best bio-diversity. This may have actually been done in the past for a later map of the area shows the meadow split into Upper and Lower Halfpenny bottom. This may not be the reason, however!
The height of the cut, or sward, must also be taken into account, as far as habitat is concerned. For example, different caterpillars favour different sward heights or plants. That is to say, certain varieties prefer to feed on long grasses while others prefer to feed on wild flowers. This is why it is good to have the meadow cut at different heights; i.e. the centre swathe is left longer.
The removal of the cut grasses and forbs too is a matter to decide. Leaving cut material to rot on the surface or act as a mulch will produce excess nitrogen in the soil and encourage grasses, while removing it may promote wildflowers. The meadow, however, cannot be left uncut at all because woody plants like hawthorn and elder will invade and, once established, be difficult to remove. For this reason the perimeter of the meadow has to be cut too, albeit less frequently.
A delicate balancing act then, when to cut, how much, to remove cut plants or leave them in situ. All these things to conserve Furzefield Nature Reserve as a resource for everyone.