Plantation woodlands are a common feature in Hampshire’s landscape. As many of these, especially some of the larger plantations, are owned by the Forestry Commission, they are well known to many of Hampshire’s residents and visitors alike. Alice Holt Forest, Micheldever Woods, West Wood, Creech Walk, Queen Elizabeth Country Park, Botley Wood, Ampfield Woods, Lords & Hut Wood at Chilworth, as well as large tracts of the New Forest all fall into this category.
Plantations, rather than relying on the natural regeneration of trees to establish or restock a woodland or forest, as their name suggests, are created by planting the trees.
Plantations are characterised by blocks of trees that are all of one age and often consisting of only one or two species of tree within each regular block of planting. Very often the species planted were non-native species and in particular conifer, but many plantations were of broadleaves such as oak or beech and often plantations were a mix of conifer and broadleaves. Whatever the species, the end result was very much concerned with a ‘crop’ of trees.
Few plantations existed prior to 1700 and those that did were often imitations of existing woodlands rather than examples of the even aged, species limited plantations we know from modern forestry practice, (Rackham 2003).
The need for plantations was driven by shortages and high demand for timbers for the Royal Navy and a rapidly industrialising society. In the 18th and 19th centuries most plantations would have been on farmland, heathland or wood pasture but some would have been in existing woodland. However in these times the methods used would generally have been fairly low input and extensive.
The 20th Century saw the creation of the Forestry Commission in 1919 in response to the difficulties Britain had meeting its wartime demands on timber. During the II World War these shortages were once again acute and the siege mentality that enveloped the country during this time ensured that post war policy for both food and timber was focused on rapidly increasing production. This was in part, enabled by the increased mechanisation and investment available to the agricultural and forestry sectors in the post war years. It was seen as both 'profitable' and in the national interest to convert existing ancient semi natural woodlands (ASNW) to plantation forestry. This was often facilitated not just by clear felling of the existing woodland but by bulldozing the stumps of trees and underwood or spraying with herbicide to prevent regrowth. Plantations on ASNW are now known as Plantations on Ancient Woodland Sites (PAWS)
Current figures suggests that in Hampshire somewhere around 33% (9300ha) of our ASNW has been planted. This compares to a figure of 44% for England.
The establishment phase of plantations would destroy much of the character and natural vegetation of ASNW , but often ground flora recovered and native trees and shrubs regenerated and strong elements of the ASNW character survived in many of these plantation woodlands. However these living elements characteristic of ASNW that survived were and still are under threat.
Plantations bring about many physical changes within a woodland including changes to humidity and temperature but perhaps most significant is there effect on light levels. Conifer plantations cast dense shade compared to our native broadleaved woodland. Their evergreen nature makes useless the tactic employed by much of our native woodland ground flora, to grow and flower by early summer, taking advantage of the leafless trees of spring time to gain their energy from the sun. Prolonged heavy shading kills of even the most shade tolerant of woodland plants. Dense plantings of broadleaves, especially beech, can also have detrimental effects on the ground flora severely limiting its diversity.
Another factor that has exacerbated the shading effect of plantations are economics. Plantation woodland by design is compact and high density. If managed correctly periodic thinning would have removed trees to allow the final 'crop' of trees room to grow efficiently until the final felling. However, since their planting, the economics of plantation forestry on medium and small scale plantations around the SE has changed dramatically and in many cases has meant that plantations have had no or little management.
There are obvious huge biological impacts from plantations on ASNW from the obvious removal of the native trees and shrubs which supported a wider biological network to the less obvious changes to soil fauna and flora through brought on by changes to the composition of leaf and or needle litter.
The longer the combination of these effects continues the greater the threat to the elements of ancient woodland biodiversity surviving. Many plantations are soon reaching there economic maturity. If these sites are harvested and replanted with conifer once more, or are left to become over mature, then these sites will deteriorate further in terms of woodland biodiversity.
As such restoration of planted ancient woodland sites is currently high on the agenda for forestry and woodland management. It is seen as one of the key actions for enhancing woodland biodiversity and targets for PAWS restoration are set in both national woodland habitat action plans (HAP) and the Hampshire ancient woodland HAP. In light of this, the new English Woodland Grant Scheme will look to support PAWS restoration with enhanced rates of payment for the restocking of plantations on ASNW with native species. The planting of conifers on ASNW sites will no longer be supported by grant aid.
The current approach to PAWS restoration looks to balance the priorities of restoring the former biodiversity of ancient woodlands with the other social, environmental and economic objectives that society and owners may want from ancient woodlands.
Given the range of factors involved, including the unique character and circumstance of individual sites, and the current limited but rapidly growing experience of PAWS restoration currently available, it seems sensible to promote a range of options for revitalizing ancient woodlands to optimise overall benefits to society. These will include full restoration of native woodland ecosystems at sites where this will create the greatest biodiversity gains, mixed conifer/broadleaved woodlands using continuous-cover type systems where biodiversity is enhanced and future options are kept open, through to continuing with predominantly non-native trees on some sites with low priority for restoration and good potential for timber values.
Plantations were also commonly planted on commons , wastes and heaths, and these are now also being restored where they are affecting other priority habitats such as heathland.
Further detailed information with regard PAWS restoration is available from a variety of sources with some key references are available in the links and resources section.