Blog: Why I look at the trees when visiting zoos

Healthy terrestrial ecosystems depend on healthy trees. Meet the conservationists doing crucial work monitoring and educating about tree diseases and pests:

When people visit zoos, they understandably focus on the animal collection. But all zoos have a collection of plants, from the displays of annuals in flower beds, to trees providing habitats, food and shade. And these trees also receive some of my attention during zoo visits. I am a forest scientist and for the last nine years I have led a project designed to educate and train people is tree health, raising awareness of the issues, encouraging surveillance and promoting reporting.

The importance of tree health monitoring

Several new tree pests and diseases have entered Britain in recent decades, and others are known to be heading our way. Some arrive unintentionally via the global movement of goods, whilst small organisms or spores may be windborne. And warmer UK temperatures may provide a more favourable environment for their establishment.

Dutch elm disease has removed most of our mature elms and currently, the spread of chalara dieback of ash is being seen across the UK. Official surveillance reduces the likelihood of these new arrivals, but it is impractical to inspect every item reaching our shores and windborne introductions are impossible to prevent.

Chalara dieback of ash can now be seen over much of Britain. Peter Crow, Forest Research

If a new outbreak is identified early enough, it improves the chances of reducing rates of spread or potentially removing it all together. Initiatives such as Observatree and TreeAlert are helping to engage with more people and provide land managers with resources to survey and monitor trees for pests and diseases.

10 years of Observatree

Since 2013, Observatree has trained and managed a network of 200 volunteers to recognise 24 Priority pests and diseases or interest. Some are already in the UK, but we are keen to understand their whereabouts. Others are thought to be absent, but those such as the emerald ash borer or bronze birch borer could have a significant impact if they arrive.  To support our volunteers and help to raise awareness, we have produced many freely available educational resources.

 There are many tree health resources freely available on the Observatree website

Observatree volunteers receiving training on taking a sample of infected tree bark for analysis. Peter Crow, Forest Research

Reporting can make a difference

In 2015, an Observatree volunteer reported a sighting of the Oriental chestnut gall wasp to the north of London (it was only thought to occur in a small part of Kent). This led to wider surveillance activities and demonstrated the potential of citizen science in supporting tree health. In recent weeks, Observatree volunteers were asked to survey for the plane lace bug following a new outbreak in London.

Observatree volunteers also submit data on healthy trees that help us to understand the extent of pests or diseases and their rates of spread. During the 10 years since Observatree began, more than 24,000 tree health reports submitted. Thankfully, 75% of these relate to healthy trees; whilst 15% were for Our priority pests or diseases. A further 10% of submissions were on other suspected pests, diseases or unknown causes.

The data are submitted through TreeAlert, the official tree health reporting mechanism in Britain (Tree Check is used in Ireland). Unhealthy tree reports are reviewed by diagnosticians within Forest Research. Registered TreeAlert users can also search reported tree health data to see what may be of interest in their area or heading in their direction.

A continued need for surveillance and a role for the BIAZA network

With sites across Britain and Ireland, the BIAZA network is well-placed to support tree health monitoring. For anyone wishing to know their elm zigzag sawfly from their oak processionary moth and explore the world of tree health further, information can be found through Observatree’s host tree species or the Host of the Month blogs. If you would like to receive updates from Observatree, our e-newsletter is sent out once every three months. Any tree health reports from BIAZA members would be gratefully received.

- Peter Crow

About the author:
Peter Crow has worked at Forest Research for more than 30 years. During this time, he has worked on many aspects of environmental forest science and helped to pioneer the use of lidar for the mapping of archaeological features in UK woods and forests. For the past nine years, Peter has led the Observatree project.

All blogs reflect the views of their author and are not necessarily a reflection of BIAZA's positions