FAQ

How do I use Treezilla?

The following video provides an overview of how to use Treezilla.

Why do some areas have a lot more data than others?

Councils and other organisations with tree inventories can upload large amounts of data in bulk. If there is no data for your area then ask your council if they have a tree inventory and if they want to take part in the project.

Can I only enter data for single trees not whole woodlands?

At the moment the system only works for individual trees, we are developing the project further so that hopefully we will be able to deal with woodlands in future.

What if I don't know the species?

Upload photos of the tree when you enter the tree details on Treezilla. Include a general shot to show the whole tree, the trunk to show bark detail, close-up of the buds on a twig, then depending on time of year also give a picture of leaf, fruit and flowers. Preferably include a ruler or other reference object in the images to show scale. The community of users on Treezilla should then help out with the identification. For common tree species an overall picture of the tree and a close-up of the leaf may be sufficient to achieve an identification but for some other species all the different parts of the tree may be needed and the ruler to show the exact size may be very important.

There are a number of websites that give help on tree identification. A sister project to Treezilla, iSpot.org, has a set of keys to variety of wildlife including trees. Currently the tree keys only cover a limited range of the species occurring in UK. However it is also possible to produce your own keys and have them included on this website, all that is needed is to fill in a simple table with tree species down the side and characteristics across the top and the computer program can convert this into a key of the sort shown on the iSpot keys page, additional information such as pictures can also be included.

Reference books are still one of the best ways to learn about and identify tree species. There are many good books available, if I had to just choose one then probably the Collins Tree Guide (2004) by Johnson and More is one of the best and can easily be taken out into the field. Many of the large gardens and arboretums have guided walks lead by rangers who can answer question about trees and there are a number of organisations such as the Royal Horticultural Society who offer a plant identification service.

We have produced a simple visual guide to street and park trees . This is a good starting point if you are not sure which species to select from the long dropdown list of tree names when mapping your trees. You may like to brows through this guide even before going out to map trees just to get an idea of things to look out for when identifying trees.

The species I want to add is not on the dropdown list?

Most of the common species and many of the rarer ones are already in the species dictionary. We shall be adding more species over time. To find a species type the first few letters of the common name or scientific name then select from the list. Make sure that you select the correct species noting that there may be several different species with very similar names, you may need to scroll down the list.

Many of the genera have an option to enter a general name such as Quercus sp. for those occasions when you know it is an oak tree (Quercus is the scientific name for oak) but you are not sure which species of oak it is. However it is always best to give the exact species if you can, for example different oak species can be small bushy trees or huge trees and can be evergreen or deciduous. Each of these types of tree will have a very different value for its ecosystem services.

Are you really trying to map ALL trees in Britain?

The short answer is yes although it may not be quite as impossible as it sounds. In urban areas particularly we want to map the trees where you can see separate tree crowns, this includes most street trees, many of the trees in parks etc. Councils already have lots of these in their tree inventories. Woodland areas, urban or countryside, can be mapped as polygons so we don’t need to know the exact location of each tree within the woodland. However to calculate the ecosystem benefits we do need an estimate of number of trees of each species and their size distribution. You may still want to map the exact location of a small number of individual trees within the woodland, perhaps to show they have a particular pest or disease or they are notable trees.

Polygon feature

This experimental feature, which is still being worked on, shows areas that have been mapped as some kind of woodland. The trees may be small or large. The areas themselves may also be small, for example along roadsides, or large areas of plantation forest. These existing polygons from Ordnance Survey Opendata only show there are trees present, there is no record of the species or size of trees – this is where you come in!

It would be an enormous task to record information for all the huge number of polygons and anyway a lot of this data is already held by other organisations such as the forest inventory. However it is often the urban areas where there is a lack of data and this is where citizen foresters can help out. For example there may be an area of woodland that you walk past and could easily note the types and size of trees, often these small areas of woodland in urban areas have a very limited range of readily identified tree species.

If you want to have a go at recording the trees in one of these polygons here are a few simple steps:
1. Register and login
2. Zoom in to the area you are interested in and click on the particular polygon of interest.
3. Click on the view/edit line. A small image of the polygon is shown along with a list of possible tree size classes (0-10cm, 11-20cm etc), the scroll bar allows you to get to large trees over to the right.
4. The method of entering the data is still being worked on but you will be able to enter the number of trees of each species in each size class.
5. If it is a relatively small polygon you may want to record all the trees. However if it’s a larger area then taking sub samples is probably better, there are standard methods for doing this which will be described later.
6. Once the data are entered hit submit.

This experimental version of the polygon feature does not calculate ecosystem services provided by the trees, it is planned to add this aspect later. However it will be possible to view and search the trees. The feature is experimental as we are looking for the best ways to deal with this type of data and enable people to edit and view the information. Currently it is not possible to alter the set of polygons shown or to add your own polygons, however this is under review. It is possible there are other sets of polygons that could be used as an alternative, or in addition, to the current information.

There are a very large number of woodland polygons. To avoid cluttering the map only a limited number of these are shown if you hit the ‘show polygon’ button when fully zoomed out to UK. When the map is more zoomed in then all the relevant polygons are shown.

How do I measure tree size?

Entering the diameter of a tree is crucial for helping track that tree’s growth and environmental benefits. Measuring the diameter can be a bit tricky though. The following video from the people at UrbanForestMap.org provides a quick tutorial on an easy way to measure your tree’s diameter.

Note in the video they use a standard height of 4’ 6” (1.37m) to do the measurements of trunk diameter however in UK we usually take 1.3m as the standard height for these measurements. For most trees the difference in diameter reading measured at 1.37 vs 1.3m is likely to be very small. The main thing to remember is to carry out the measurement at approximately this height and not at a much lower height where many trees start to splay out. Also try to be as accurate as possible with the measurements, people may want to come back to that tree in future to see how much growth there has been.

How do I measure tree height?

Foresters use a clinometer when measuring tree height. The device measures the angle to the top of the tree. The foresters also measure the distance from where they are standing to the base of the tree and then use simple trigonometry to calculate the tree height. Smartphones also have apps to calculate tree height but beware it is easy to make big errors when using these apps. Only fill in the height if you have repeated the measurement several times and you are sure it is correct.

Is there a forum to discuss treezilla?

Yes iSpot Treezilla forum http://www.ispot.org.uk/node/340006. However you will need to log into ispot to be able to use the forum. At present we don’t have a forum on the Treezilla site itself although you can write in the comments box for the individual trees.

Don't forget to check back on treezilla to see if others have commented or added ID to your trees!



How do I identify tree pests and diseases?

Some of the recent pests and disease threats to Britain’s trees are shown. Note that many of them are difficult to identify so you should go to http://www.forestry.gov.uk/pestsanddiseases to see a full description of each of the conditions.

Some of the characters in the advanced filter are not complete

When using the advanced filter or looking at an individual species page, some of the information on autumn colour, edibility or other characters may be missing. We have not had time to fill all of this in for the 1300+ types of trees on treezilla. We are also being quite conservative about edibility just showing those species that are good to eat such as apples rather than showing all species that have some part of the tree that can be consumed after appropriate treatment.

Why can't I edit fields in the Affiliations section?

Currently, input to this section is limited. Either editing is not allowed at all or there are a limited number of options selectable from a drop-down list. These options will be reviewed once the system is being well used.

What are the ecosystem services?

Trees and other wildlife as part of the living ecosystem around us provide various ‘services’ to humans. These services include: cleaning pollutants from the air, reducing storm water flows that can overwhelm the urban drainage system, ameliorating the climate in urban areas so saving energy costs of cooling buildings in summer and heating buildings in winter. Trees also take the greenhouse gas carbon dioxide from the atmosphere and produce the oxygen we need to breathe. On a larger, landscape, scale intact forests can help with water storage and reduce pollution from soil erosion. Trees can also create a sense of wellbeing, people like being in areas of green space with trees, property values are higher in areas with trees compared to similar areas without trees.

It is possible to calculate a monetary value for each of these services. The numbers are based on a huge amount of scientific research and detailed measurements of trees over many years but they can still vary widely depending on various economic assumptions. One of these underlying economic factors that differs between the US and UK, and which can have a large effect on the monetary figure shown, is the difference between externality costs, used in US, and social damage costs, used in UK. Basically externality looks as the cost of using technology such as a machine to remove the pollution whereas social damage deals with costs associated with the impact on human health and damage to buildings and crops.

The detailed scientific measurements of just how much of each type of pollutant each tree species of each size is removing from the atmosphere throughout the year, combined with the range of economic considerations, means there are a variety of different interest groups with views on how these calculations should be carried out.

The ecosystem services provided by urban trees can have a large monetary value, for example a tiny part of central London, Victoria, has just 1200 trees. A detailed analysis of the area showed they remove 1.2 tonnes of pollution with a value £85,000 (on UK social damage cost basis) per year, they also attenuate 112,000 cubic metres of storm water with value of £50,000 per year. When these analyses have been carried out citywide in a few parts of North America and Europe and included all the different ecosystem services then urban trees often have benefit values of tens of millions of pounds per year. The benefit numbers take into account the costs associated with planting and maintaining the trees.

Some of the detailed methods and references are shown on the i-Tree website, which has been run by USDA forest service for a number of years. The methods are being modified and parameter values adapted for the species of trees growing in UK and under the UK climatic conditions. Some of the scientific measurements required for these modifications have already been carried out and other measurements will be carried out in UK cities during 2013/2014. This means that the ecosystem service numbers are likely to change as more measurements become available and it is possible to improve the parameter values.

A comparison of the ecosystem service numbers produced by the Treezilla system compared to the very detailed i-tree eco calculations for 1000 trees indicated that the overall values for pollution removal were similar for both systems. However there was quite a lot of variation tree to tree so you should only use the values on Treezilla as a general indication not as a precise figure for individual trees.

Your turn

Our database of trees comes from public records and citizen foresters like you. Add a tree today and help us grow!