On the 11th of February a small team of volunteers set out to map every tree in the arboretum. We had no idea how many trees there were, no idea of the full range of species or if they were all easy to get to, but we did know we had just a week to get the job done.
Our objectives were to record:
- The position of each tree (eastings and northings)
- The species of each tree (latin and common name if known)
- The current tag/tags for each tree (if any even present)
Why we are mapping
The arboretum, has not seen any mapping for a number of years, with only a hand drawn map in our possession which is extremely out of date. On top of this there are two existing numbering systems, one from the 80s, one from around 2001, both incomplete with many trees missing tags. There is no record of what trees are in the collection or how many, what species they are or where they are.
With a new map we will finally know what trees we have and be able to access spreadsheets to easily browse the collection, informing new planting and providing information to visitors. Another big outcome will be to aid management, with it becoming possible to reference each tree and easily and quickly find it’s location on site.
Our chosen method
In the past arboretums were mapped using links and chains, long pieces of metal chain stretched out to measure distances, together with a compass to determine the angles, these measurements were scaled down onto paper and a map was produced. In modern times thankfully we have systems like GPS (Global Positioning System) to help us plot our location on the earth’s surface and fancy technology to get this down to sub-meter accuracy – nice!
We chose to hire a handheld device from a small specialist company (see notes below) who were able to preload the device with an Ordnance Survey map outlining the arboretum’s boundary. This was used together with a Geode GPS receiver to boost the signal to get sub 50cm accuracy and better cope with the reduced signal which is often a problem in woodlands. We had purposely waited until late winter to make sure the trees were as bare of leaves as possible but there were still the branches, coniferous trees and low sheltered areas to deal with.
The device was preloaded with specialist software (PocketGIS) that enabled the input of lots of tree data, like species, tag number, condition as well as information like whether there was a tree protection order and other such things less relevant to our situation. To enable us to go as quickly as possible we chose to just capture the minimal essential amount of information on the device, whilst also using a clipboard to note down supplementary things like the diameter or maintenance issues (such as damaged tags or old wire guards to be removed).
Once done the data could be exported as a .csv file and imported into a mapping program. We had chosen the open source (free!) software call QGIS, which has a really good community and lots of documentation.
With much relief we had good weather, still and sunny days ahead, perfect for the task in hand. We started out tentatively recording trees (choosing a large Deodar Cedar to be tree number 1) and slowly making sure we had our information correct, doing occasional checks and cross referencing to make sure. Things quickly picked-up speed though, by the first afternoon we were zooming along from tree to tree, speaking in strange shorthand code that was to become the mainstay of the rest of the mapping days ahead:
It was really enjoyable though, each person with their own role working as part of a wider team. The subtle nuances of the different trees and measurements was very absorbing. Where possible we also stopped and looked at the buds and talked about the origins of the specimens. Our winter tree ID skills grew rapidly, especially the differences in texture and colour of each tree’s bark.
Each day we had a different group of people, with some returning for multiple days to help make sure the job got done. The work was very engaging and it was such a pleasure to spend the week out in the open air with like minded company.
At times the mapping was quite difficult, with some trees being very hard to reach (especially to get to the actual trunk), we had to crawl under conifer boughs, fight past bramble and find new ways to get the recordings we needed.
Towards the end of the week, we started to realise we were running out of time, so the pace increased, the banter and chat lessened as we focused into the task. On the last day a large section of the woods was finished in one go, with a great sense of pride and relief as we recorded the last tree (a hornbeam).
We are very much indebted to the dedicated volunteers who gave so much time and enthusiasm over the week. Also a massive thank you to The National Lottery Heritage Fund for making it all possible.
The next thing to be done is to bring all this data together into a spreadsheet, both from the device and typing up the sheets of supplementary data from the clipboard. The data will also need to be cleaned (checking for errors and anomalies) and occasional rare trees will need to be verified, to make sure we have the correct name and genus. Once this is complete it can all be brought into QGIS, where it can be visually plotted out and maps can be created.
Once we have created the maps these will be shared online, along with historical data and articles we have been archiving – watch this space!
A very special thank you to The National Lottery Heritage Fund for making this all possible.
CT5 running android (Juniper Systems) and PocketGIS, connected via bluetooth to a Geode GPS receiver.
Hired from Pear Technology [https://www.peartechnology.co.uk/]
- Diameter/circumference measuring tape (fiberglass)
- Stick of bamboo for 1.5m marker (height of measurement)
- Clip board