Notes from an Award Winning Farm – Woodlands
This relates to small woods of 5 acres. All were planted in the middle of the C19 as fox and game covert. A number of these were compulsory felled during the last war, replanted after it and ignored for thirty years after the young trees were established.
The post war planting consisted largely of ash and sycamore, with some oak and beech, usually between rows of larch or Scotch pine. All the conifers, and most of the oak and beech, were quickly suppressed by the ash and sycamore.
Neglected woods need drastic thinning to open up the canopy and give the remaining trees room to grow. Thinning also lets in the light which encourages undergrowth and wildlife below. Few people realise that over the years forty eight or nine out of every fifty trees planted have to be removed, if the last few are to reach full size at maturity. Passers-by seeing thinning in progress are usually strongly critical or even hostile.
In the thinning, we particularly try to free the hedges, often partially supressed by trees growing too close. This clearance much improves the woodland edge where most wildlife feeds or breeds. If woods are big enough the creation of rides provides further woodland edge habitat. Ours are really too small to create effective rides so we concentrate on edges and the occasional small open area inside.
Once woods have been opened up we try to enrich both the understorey and the ground flora with the aim of providing more food and shelter.
The understorey left after thinning is mostly spindly hawthorn and elder, much of which we cut down to encourage denser and more vigorous regrowth and wych elm regeneration. We plant further hawthorn and also alder buckthorn for the brimstone butterflies, sallow for a whole range of moths and other insects, honeysuckle for white admirals, rowan and white beam for blossom and berry, hazel for catkins and nuts. For evergreens we plant holly yew and ivy, primarily for winter shelter though all will eventually add to the food supply. Holly and Ivy are particularly valuable in winter. Occasionally in gaps we supplement these and increase the variety of timber species with small groups of Norway maple or lime whose flowers will increase the nectar supply in late March/April and late June/July respectively.
Increasing the variety of ground flora is more difficult. On our rich clay soils the usual undergrowth of nettle, willow herb, thistle and bramble grows over 6ft high in a season. Smaller flowers cannot compete and get suppressed unless they flower early in spring or tolerate more shaded areas. Bluebell and pink Campion spread by seeds thrive in attractive and intimate mixture. We’ve succeeded more recently with dog and sweet violet, lesser celandine, bugle, wild daffodil foxglove and hoping to introduce the silver washed fritillary. Yellow archangel, bitter and tufted vetch (for wood white butterflies), wood sorrel and wood anemone, ox-slip and primrose (hard hit by summer droughts) are difficult to establish.
For new planting we plan a much more varied mixture from the start. Much well intentioned advice supported by a grant system encourages planting pure hardwoods, and using only native trees and shrubs. The thinking behind the latter principle is that many more insects feed and breed on native species, and insects provide food for birds and mammals.
Neither principle should be followed too closely. The weakness in the approach is that young deciduous woodland is for many years a regiment of bare poles. These are cold and draughty in winter, offer little cover and few nest sites in summer, and are generally unattractive to wildlife at all times of year. Woodland in the pole stage is vastly improved as habitat by a generous mix of conifers. We aim for at least 60%conifers, most of which will come out as thinnings in the first 30 years. Even at 40% hardwoods 9 out of 10 will have to be removed before maturity. One shelter belt, now an attractive mixture of beech and wild cherry, was planted 30 years ago with 80% conifers. All the latter have gone and the hardwoods are still too crowded and need further thinning.
All woods need a good amount of evergreen cover as shelter for breeding and roosting birds and hibernating insects. In mature deciduous woodland much of this can be provided by holly, yew and ivy, but none of these grow quick enough to provide it in the early decades. One needs conifers which offer major silvicultural and economic advantages. Hardwoods usually grow better and straighter with a conifer nurse, and softwood thinnings are of value from an early age, while except as firewood, hardwoods have little value for decades. To think that because we want mature deciduous woodlands in a century’s time we must plant all or mostly hardwoods now is nonsense. To do so is to confuse the end with the means.
The weakness in the native species approach is that it overlooks both the limited period of flower and fruit provided, and wildlife’s changing requirements at different seasons. Butterflies, moths and many other insects need nectar sources to feed on as well as larval food plants. Birds and mammals eat larger quantities of seeds and berries in autumn and winter. Provision of all these can be increased in quantity and extended over longer periods by planting introduced species.
To help wildlife survive the periods when it is most vulnerable, we try to identify the weak links in the annual pattern of its existence. Both observation and common sense suggest that these occur during the breading season and in harsh winter weather. Evergreen conifers provide cover and shelter and they with other introduced trees and shrubs can extend the food supply during both periods of danger.
In practice, all this means that we are planting mixture of mostly native hardwoods, conifers and smaller trees and shrubs. The choice of species is intended to provide a varied and long-lasting sequence of catkin, blossom, larval food plant, nest site, berry and shelter. Where introduced species can lengthen or strengthen any stage in this sequence, we include them. To give a few examples we plant salix aegyptica for catkins which flowers 3 or 4 weeks before S.caprea or cinerea. For blossom we plant myrobalan or cherry plum which flowers 3 weeks before blackthorn. Whitebeam (Sorbus Wilfred Fox) which supplements rowan and hawthorn both in blossom in early summer and for berries in autumn much favoured by thrushes and visiting redwings and fieldfares. For nest and shelter a few Deodar or Grand Fir in small groups inside the wood.
These methods seem to work well in practice, even if they do not always follow current fashions in conservation theory. Birds have responded well, helped by nearly 200 nest boxes on the farm. We have all the species normally associated with small woodlands, and many of those usually only found in larger woodlands. For insects it is difficult to quantify but drastic thinning has encouraged some ten specie of butterfly to appear regularly, and we hope further clearing and establishing food plants will eventually attract another five. The surprise has been the number of dragonflies that now hawk along the tracks. The presence of these predators suggests a flourishing insect population for them to feed on.