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How ancient is ‘ancient’, and does it matter?

As a concept, ancient woodland is remarkably recent, and has only really become part of our day-to-day arboricultural thinking since the 1980s. The 1985 Forestry Commission reviewBroadleaves in Britain was one of the first ‘official’ publications to acknowledge its existence, and to suggest it was (for all practical purposes) ‘irreplaceable’, this status now being enshrined in national planning policy, within paragraph 118 of the 2012 National Planning Policy Framework (NPPF), which rather annoyingly omits the ‘for all practical purposes’ bit.

The mapping of this resource, in the form of the Provisional Inventory of Ancient Woodland, commenced during the 1980’s, but largely confined itself to recording of woodlands of over 2ha in size. The Inventory was (and still is) entitled ‘Provisional’. The more recent revisions to District or County AW inventories (AWIs) have sought to include all ancient woodlands of 0.25ha and over, with the result that in most cases, their recorded areas of ancient woodland have increased, rather than diminished. This seems paradoxical, when we are constantly being told by various conservation bodies how scarce it is.

Another result is that ancient woodland, and the effects of development on it, are increasingly common issues in the planning arena. More often now, the exact status, and value, of areas of woodland identified as ‘ancient’ in the AWIs are being questioned, due to the policy protection afforded to them under the NPPF.

So how ancient is ‘ancient’? The definition seems simple enough: Ancient woodland in England is defined as an area that has been wooded continuously since at least 1600 AD. Ancient woodland is divided into ancient semi-natural woodland and plantations on ancient woodland sites. Both types of stand are classed as ancient woods.

This doesn’t mean that an ancient woodland has to contain ancient trees, nor that it must have never been felled or managed. On the contrary, many woods have only survived over the centuries because they have been regularly cut for coppice, or had their larger standard trees felled and replaced, for a whole suite of different wood products and uses. Even where the original broadleaved tree cover was removed, and replanted with non-native, fast-growing conifers (as frequently happened in the early 20th century), to a greater or lesser extent the woodland soils, and their associated invertebrate fauna and flora, maintain their integrity and continuity, and hence are still classified as ‘ancient’.

The date of 1600 AD as a ‘cut-off’ for whether woodland is ‘ancient’ or not also needs some explaining. It is essentially a convenient point in history where accurate maps started to be made (at least sporadically in different areas), and before the planting of new woodlands became a popular pastime for landowners. Other (later) dates have been chosen (and argued about), but 1600 is the date adopted for practical and policy purposes in England.

However, there is (or at least originally was) an important underlying assumption to this – namely that if a woodland existed in 1600, it is likely that it must have existed as woodlandthroughout historical times before that, and had not previously been cleared or converted to other land uses during the historical period.

So it is not the fact that a woodland has existed for 400 years which makes it ‘ancient’ in the true meaning of the word, but the assumption that if it has existed for 400 years, it must have existed for an indefinite period previously. Archaeology, and history, have subsequently shown this to be a bit shaky, but that goes beyond the scope of this piece – in policy terms 1600, box ticked, job done. Ancient.

But how easy is it to show that a woodland was in existence in 1600 AD, and are the AWIs produced for different areas of the country sufficiently robust to provide the basis for a planning policy which imposes a major constraint on development affecting the woodlands they identify?

At the risk of over-simplification, the starting point for the compilation and updating of the provisional AWIs is the first edition Ordnance Survey 25 inch to 1 mile maps, produced variously between approximately 1860 to 1880, often referred to as “Epoch 1” maps. Comparison of these with the present-day Ordnance Survey MasterMap readily eliminates woodlands of late 19th century and 20th century origin. Because of the high degree of accuracy and detail with which the Epoch 1 OS maps were drawn, the absence of a wood from these is normally sufficient to eliminate it as being ‘ancient’.

Refinement of this consists of checking against a range of other historical maps, to confirm the continuous presence of woodland cover at earlier dates. In this process, Tithe Maps are an important resource, having been created generally on a parish by parish basis, with accurate depictions of land use and apportionment. However, in many cases these are of variable accuracy and quality, and do not greatly pre-date the OS Epoch 1 mapping, having often only been produced in the first half of the nineteenth century.

The existence of reliable earlier mapping against which to compare the 19th century maps is variable according to county or region, and is often complicated by the conventions and priorities of the earlier map-makers themselves – for example, the military origins of the very first Ordnance Survey maps (produced in the early years of the nineteenth century)  resulted in their focussing on topography, denoted conventionally by dense hachuring at the time (rather than by contours), which frequently obscured other detail. Likewise, some earlier maps suffer from having been commissioned by individual estate owners, who often preferred their domains to be depicted as they wished them to be, rather than as they actually were.

There are exceptions – in Surrey, for example, the John Rocque map of the county of 1768 gives a systematic indication of land use, including woods, heaths, commons, marshes, plough land and pasture, and boundaries of woodlands shown on this map can be correlated, in many cases, with those on the later OS Epoch 1 maps. In Kent, mapping of varying levels of accuracy and detail is available, at least for parts of the county, back as far as the Symonson map of 1596. Other evidence sources, such as topographical features, shape of woodland boundaries, and the names of woods themselves, can yield some clues as to the status of a woodland as ancient or otherwise, but this is also patchy and not always reliable.

So tracing a woodland’s existence back to 1600 on the basis of map evidence is not straightforward, and in a large number of cases, inclusion of a wood as ‘ancient woodland’ on the provisional AWI may be based essentially only on maps dating from the mid-nineteenth century, some 250 years after the threshold date. Somehow, this doesn’t seem totally satisfactory.

It is field survey which provides the strongest evidence for a wood’s antiquity, through the presence or abundance of what are termed ‘ancient woodland indicator species’ – species of woody or more typically non-woody plant species which are slow to colonise or spread, and whose presence therefore indicates a long history of little or no disturbance to the woodland soil. In addition, the presence of archaeological features indicating a long history of traditional management practices, such as charcoal hearths, saw pits and boundary features such as woodbanks, can be powerful evidence of a woodland’s ‘ancient’ status.

The species composition of the wood itself, and the presence of, for example, large or ancient coppice stools or boundary pollards indicating a long history of traditional management are also strong clues, although this sort of evidence is often absent in woods converted to conifer plantations in the early part of the twentieth century, as well as in woods ruthlessly grubbed and replanted with (what was then highly profitable) sweet chestnut coppice in Kent and Sussex during the mid-to late-nineteenth century. Such woods are frequently categorised as PAWS (plantations on ancient woodland sites), which are considered to have an equivalent status, in terms of national planning policy, to ancient semi-natural woodlands (ASNW), but this may again be based only on their presence on nineteenth-century maps.

The time and resource pressures placed on the bodies tasked with updating the AWIs for their areas render wholesale field survey of possible ancient woodlands simply not feasible – as a result, only a small proportion of woods included on the AWIs will have been subject to actual ground survey prior to their inclusion, and their listing will have been on the basis of maps alone.

All this creates a fertile field for debate where development is proposed in the vicinity of woodland identified as ancient on the provisional AWI. Paragraph 118 of the NPPF states:planning permission should be refused for development resulting in the loss or deterioration of irreplaceable habitats, including ancient woodland and the loss of aged or veteran trees found outside ancient woodland, unless the need for, and benefits of, the development in that location clearly outweigh the loss’, but the constraint doesn’t simply stop at the woodland boundary – the Forestry Commission & Natural England Standing Advice explains why development in close proximity to an ancient woodland can result in its ‘deterioration’, and hence stipulates the requirement for a ‘buffer zone’ of a minimum 15m width between the development and the woodland, which is intended to prevent the adverse effects leading to ‘deterioration’ of its value.

Recently, an increasing number of planning cases have involved the need for scrutiny and careful assessment of a woodland’s status, and whether it has been correctly identified as ‘ancient’ or not. In cases of this sort, four lines of investigation are typically pursued:

  1. historical, through careful assessment of the available mapping information to dtermine whether the area can genuinely be shonw to be liely to have been present in 1600.
  2. ecological, through botanical field survey to asses the presence and/or abundance of the requisite number of ancient woodland indicator plant species, and the ecological value of the site.
  3. archaeological, through field and LIDAR surveys to ascertain presence of features or structures indicative of long-standing historical management, frequently supplemented by seed and pollen analysis of soil samples 
  4. arboricultural, to assess the ages, species, and condition of the trees present - including standard trees and coppice or underwood, if present  - and the likely history and continuity of the woodland's managment 

Within the AWIs, it is accepted that new evidence may come to light on a particular site that challenges its ancient woodland status, and in such cases, Natural England will consider the evidence and decide whether a woodland (or part of it) should be removed from, or added to, the inventory. Hence the continuing title ‘Provisional’.

But that is not the end of the story, as recent important decisions have shown that a woodland being ancient does not automatically mean it is sacrosanct, despite the term ‘irreplaceable’ being applied to it in the NPPF, and the declared stance of many conservation bodies (notably the Woodland Trust) to prevent any loss of its area precisely for that reason.

Inspectors, and the Secretary of State in turn, however, have taken a more analytical approach:Not all ancient woodland is the same and, in order to properly balance the harm against the benefits, the characteristics of the ancient woodland in question must be assessed was a key sentence in the Inspector’s report in 2013 on a controversial quarrying application within an area of PAWS chestnut coppice at Oaken Wood, near Maidstone.

In a more recent decision (October 2015), another Inspector went further: designation as Ancient Woodland is only shorthand for an indication of ecological interest; it is the ecological interest itself which is of value rather than the designation as such….the designation of the area as Ancient Woodland and the argument about its designation is something of a red herring. Designation itself does not comprise ecological value; it recognizes it, provided it is accurately done.

These decisions have made it clear that it is simply not good enough for objectors to recite the ‘irreplaceable’ mantra as sufficient reason to refuse a development affecting ancient woodland – both the status, and the value, of the woodland must be examined in order to arrive at the planning balance of whether the need for, and benefits of, the scheme being considered outweigh the harm caused by the loss or deterioration of the habitat.

And this is where we come in – at David Archer Associates we can undertake the investigations, surveys and research to assess ancient woodland affected by proposed developments, in order to provide robust, evidence-based analysis to support planning applications or appeals where the test set by paragraph 118 of the NPPF is engaged, and the answers to the questions Is it really ancient woodland? and Is it valuable ancient woodland?are likely to be decisive.

 

Authored by: Mark Mackworth-Praed

Mark was the arboricultural expert witness for Gallagher Aggregates Ltd. at the Call-in Public Inquiry relating to the proposed quarrying of Kentish Ragstone within 33ha of sweet chestnut coppice PAWS at Oaken Wood, Barming, near Maidstone. The Secretary of State granted planning permission for the scheme in July 2013