Forestry Commission logo

National Forest Inventory - Frequently Asked Questions

What is the NFI and why is it happening now?
Great Britain’s trees, woodlands and forests are one of our countryside’s greatest assets. Trees provide a haven for wildlife and people, help mitigate climate change, provide rural employment, and form an integral part of many of Britain’s most beautiful landscapes.

The Forestry Commission is the government department responsible for the protection and expansion of Britain's woodlands, and our mission is ‘to protect and expand Britain's forests and woodlands and to increase their value to society and the environment’.

To help fulfil this mission we are undertaking the National Forest Inventory (NFI) of Great Britain. This will help to reveal what the area of existing woodland is, the nature and condition of the woodland and, most importantly, whether the state of Britain’s woodland is improving or declining.

With this information we can better help to protect and increase the value of Britain’s woodland and forests. To achieve this, and in accordance with our responsibilities under the Forestry Act (1967), our surveyors will visit approximately 15,000 one-hectare sample squares that have been randomly plotted across Britain to gather representative information about our woodlands.

What does the NFI entail?
Each one-hectare NFI survey will typically be conducted by one surveyor within one day in a self-contained fashion requiring no input from woodland owners or managers. The surveyor will take a variety of measurements in the wood, such as tree species, tree heights, tree ages and woodland area. We will then use this information to assess the biodiversity value, condition and general health of the woodland, as well as any sustainable timber potential. The timber potential will be fed into the Forestry Commission’s Production Forecast.

How does the NFI relate to environmental and other ‘green’ issues such as carbon sequestration, biofuel potential etc?
The NFI is crucial for assessing the current status of Great Britain’s trees, woodlands and forests in relation to all these issues, and enabling any policies to be formulated in an informed manner. The NFI also provides a benchmark for monitoring the various policies and targets in these areas as they progress.

How does this differ from other surveys and/or land access requests (e.g. surveys from other parts of local and central government)?
The NFI has different stakeholders, timescales and reporting requirements from other surveys, so the method and design of this survey are different, as are the locations of survey squares and the funding of the project. As a result, the access requests and survey logistics of the NFI are being handled separately from other projects.

When will the results of this survey be published?
Information on the results of the NFI survey will be appearing on our website between June 2010 and 2014. These results will be presented at national, regional and local scales, but there will be nothing that enables information relating to specific woodlands and/or owners or land agents to be identified.

What use is the inventory?
The information in the NFI is extremely useful to a range of people and organisations involved in land and forest management and planning, policy development and business. Among other things it gives them a "baseline" of information against which they can measure changes. For example, forestry planners working to ensure that our forests are fit to survive likely changes in Britain's climate can use the data to observe changes in woodland species composition over the years which might be caused by changes in the climate.

The forestry and timber industries can use it to update their information about how much timber is growing, where it is growing, what type of timber it is, when it will be ready for harvesting, and similar matters. This enables them to plan ahead for any new investment they might need.

People concerned with wildlife and nature conservation can get important information about the state of our woodland heritage, for example, the success or otherwise of programmes to conserve rare species.

It allows the nation, and individual regions, to see whether their woodland area is expanding, reducing or staying the same. It holds information relevant to the management of pests and diseases that affect woods and forests. And it gives governments important information on which to base future policies and decisions about woodland management and development, for example, where new incentives might help to encourage certain types of woodland planting or management.

Information gathered for the NFI also helps us to meet certain international commitments that the United Kingdom has made, such as reporting to the United Nations Food & Agriculture Organisation's Forest Resource Assessment process and Forest Europe and the Ministerial Conference on the Protection of Forests in Europe.

How is the information gathered?
There are three main ways in which we gather the information that is fed into the inventory.

The first source of information is aerial photography. From time to time we and other government organisations commission aerial photographs of woodland areas. These can be useful for, among other things, monitoring the expansion or reduction of woodland in the landscape. For example, comparing new aerial photographs with old ones can enable us to spot new areas of woodland that have been naturally regenerating, or where the woodland area has declined.

The second is by a ground survey of a statistically random sample of 15,000 1-hectare (2.5-acre) plots of woodland scattered across England, Scotland and Wales. Surveyors will visit each of these plots once over the five years from 2009 to 2014 to gather a range of information about them. This will include recording the tree and plant species growing in the plots, their numbers, heights, density and the general condition of the woodland. They will return to a random sub-set of plots five years after the first visit to record any changes that have taken place.

The third source of information is a collection of ‘other’ datasets such as remote sensing imagery (high resolution photos of GB taken by satellite), together with owner’s own information on the forests.

Has such an inventory ever been compiled before?
Yes, we have been undertaking similar woodland surveys and compiling forest inventories at roughly 10 to 15-year intervals since 1924. A great deal of change in Britain's woodland and forests has taken place over the decades, so it has been important for us to keep the information up to date with regular new surveys. The inventories used to be known as the National Inventory of Woodlands & Trees (NIWT) and the most recent NIWT report, which was published in 2003, is available at

Why 15,000 plots? And how were they selected for the survey?
The plots were selected by a random selection process designed by statisticians and applied to the whole of Great Britain. The number of 15,000 is based on surveying one hectare for every 180 hectares of known woodland. Our statisticians calculate that this is the ratio needed to give us a statistically valid representative picture of the state of Britain's woodland.

I own or manage a woodland that will be surveyed - will specific details about my woodland be published in the NFI reports?
No, the information collected about your woodland will be treated in strict confidence. The NFI reports are produced as summaries for Great Britain, England, Scotland and Wales, and summaries for regions in England and Scotland. Therefore any information about your woodland will only be used to contribute to a summary about the woodland in your region, country or Great Britain as a whole - no information about individual woodlands is given.

It is possible that "customised" summary reports for smaller areas than the regions might be produced on request, but these, too, will be written in such a way that no information about any individual woodland or owner will be given.

Can the information about a woodland be used against the owner or manager?
No, the information will not be used to police or regulate any woodland. The survey is solely for the purposes of taking a 'snapshot' of the state of Britain's woodland at a moment in time, and does not involve any element of judgement of the merits or quality of anyone's woodland management.

Will the survey cause any damage to land, property or woodland?
No, the surveyors' visits are very low-impact and unobtrusive, and we will not be damaging any trees or plants. The only visible sign that the surveyors were ever there might be a small, discreet peg placed in the ground to provide a reference point for a possible return visit in five years. We will consult woodland owners or managers to seek permission to leave pegs.

Do the surveyors need any help from the woodland owners?
We can conduct most survey visits without help from owners or managers. However, where woodlands are some distance from a pubic highway we might ask owners or managers for permission to take a vehicle on to the land to save time and taxpayers' money. So we might need to ask them to unlock gates for us, or provide us with keys so that we can unlock them ourselves. All gates etc will be left the way they were found, and keys returned.

How do woodland owners or managers know when the surveyors are coming?
We will write to them a few weeks before we are due to visit the woodland to make the necessary arrangements.

What if the timing is unsuitable?
If this is the case, the owner or manager should let us know when they receive our letter and we will do our best to reschedule the visit to a mutually convenient time.

Can an owner or manager refuse to give the surveyors access to their woodland?
Although we do have powers under the Forestry Act to enter private land without the owners' consent, we would rather not use them, preferring to make the visits in a spirit of friendly co-operation. If any owner or manager has a particularly strong objection to our surveyors' visiting, we might be able to explore the possibility of visiting another site, but to ensure that the survey is statistically valid we prefer to visit our first-choice woodlands if we possibly can.

What happens if the person who receives the letter no longer owns or manages the woodland in question?
The letter will explain what to do if this is the case. Former owners, managers or agents will be asked, if they can, to tell us the name and contact details of the new owner, manager or agent. Otherwise they should tell us that they do not know who owns or manages it now, and we will try to find the new owner or manager by other means.