Hertfordshire Biological Records Centre - Wildlife

Ancient woodland

Ancient Woodland is land that has had a continuous woodland cover since at least 1600 AD and has only been cleared for underwood or timber production. It can be placed in two categories:-

Ancient Semi-natural Woodland (ASNW) – woodland that retains a native tree and shrub cover that has not been planted, although it may have been managed by coppicing or felling and allowed to regenerate naturally. This covers all stands of ancient woodland which do not obviously originate from planting.

In terms of its nature conservation value, ancient semi-natural woodland is regarded as the most important woodland type in England because :-

The variety of native woodland plants and animals it supports, many of which are found only or mainly in ancient woodland and their links to the genetic material of the original “wildwoods” which once covered most of England.
The natural and undisturbed water courses
The soils, which may never have been ploughed
The variety of woodland structure (often including very old trees and dead wood) and other semi-natural habitats like grassland, heathland and marsh which may survive within the wood, often a result of past management practices such as pollarding, coppicing, or livestock grazing.

Ancient replanted Woodland (AWS- ancient woodland site or PAWS - plantation on ancient woodland site) – woodland where the original tree cover has been felled and replaced by planting, often with conifers and usually this century.

In ancient replanted woodland the original woodland structure may have been substantially altered, water courses may have been displaced, soils may have been ploughed or drained and natural openings may have been planted up. However, these woods can still be important for nature conservation due to :-

Remnant ancient woodland plants and animals which survive beneath the replaced canopy and along woodland rides and in glades.
The soil seed bank which will often retain ancient woodland plant seeds and fungi
Their potential to be restored to a semi-natural condition.

Other important terms are:-

Primary woodland constitutes the relicts of the natural tree cover which developed after the retreat of glaciation 10,000 years ago. Such woodland may have been managed by man, but it has never been completely cleared of trees and converted to another land use.

Ancient secondary woodland is woodland that had developed on land which may have been openground or farmland at some stage before the year 1600AD. Many ancient woods in Hertfordshire are likely to be of this type.

The Ancient Woodland Inventory was set up in 1981 by the Nature Conservancy Council to identify woodland in Britain which had existed since at least 1600 AD. Determination of this status is based on information from old Ordnance Survey and estate maps, information about the name of the wood, its shape, relief, internal boundaries and location relative to other features such as parish boundaries. Ground survey information such as flora and historical features plus aerial photography interpretation when available.

Natural England's database includes approximately 22,000 records of ancient woodland in England. Only sites over 2 hectares are included on the inventory. Some sites are smaller because part of the original wood may have been grubbed up since the 1930s base map was produced, leaving a remnant of less than 2 hectares. In addition measuring techniques were less precise than the latest digital methods so some smaller woods may have been added accidentally while some woods slightly larger than 2 hectares may have been overlooked.

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