At the end of our mapping week we had surveyed every tree in the arboretum (see previous post), we knew the tag ID, species if labelled and diameter of the trunk. The next step was to turn what was essentially a long list of numbers into a map.
First the data needed to be collated and cleaned, the measurements and notes from the clipboard along with the data exported from the device were brought into a spreadsheet. Occasionally a decimal place needed to be adjusted, tree species which were not listed in the device software were verified and added to the records.
Next the spreadsheet was imported into QGIS, the software we had chosen to create the map, in a comma separated format (.csv). Once correctly placed using the eastings and northings provided by the GPS device, each tree label could be set and a style added for the position.
Physical details needed to be added like the stream, bridges and boundary. To verify positioning, publicly available data such as Google satellite and Ordnance Survey imaging could be used. We also got to add in our new pathways for the site – the culmination of many years of work with volunteers, recovering and creating new access throughout the site.
The finished maps
We chose to create two maps:
- A map for management – this would have each tree, labelled and fine detail for the boundary and other physical details.
- A visitor map – this would just have the pathways and some notable trees within easy distance. Less detail and friendlier for new visitors to the site.
- Number of trees: 609
- Number of species known: 119 (including variants)
- Number of species to properly ID: 206 (no tag / verification needed)
- Largest tree: a veteran sweet chestnut with a diameter of 254cm
- Some notable trees we didn’t previously know about: Cut-leaved White Mulberry, Japanese Bigleaf Magnolia, Willow-Leafed Pear and many more!
Now we have all the data we can begin looking at what to plant next and how to expand the collection we have. We can also start to retag trees that are missing tags, and follow up on the initial management notes created when surveying. There are also a lot of trees to identify, a job which will be ongoing and may take some time!
And as usual thank you to our individual donors and to The National Lottery Heritage Fund for making this all possible.