Bark beetles and other alien insects could damage our forests

The Forest Service personnel who patrol our docks ensuring that alien insects do not arrive in Ireland have a tough task. A recent TV programme showed the virtual impossibility of checking the vast numbers of containers that arrive daily in our docklands from all around the world.

Our booming economy has produced this increase in imports and the sheer volume of goods, many of them packed in wooden cases or on pallets, makes inspection of all wooden goods a logistical nightmare.

Apart from wooden pallets and packaging, we also import a huge quantity of plants from all around the world to supply our garden centres and landscaping industries, and any one of these plants could harbour an insect or two that has the potential to wreak havoc in our woodlands.

So far the inspectors have done an excellent job, but the gradual warming of our climate means that some of these alien bugs that would have previously died off during a cold winter could now survive.

The Sitka spruce is a wonderful tree and has for many years been the mainstay of our forest industry. Sitka grows rapidly in Irish conditions and does so on a variety of soil types.

It provides everything from fencing posts, to pulp wood, to timber for the construction industry and being relatively easy to establish and grow, it was naturally the tree of first choice on sites throughout Ireland.

However, a warmer climate does not necessarily suit Sitka and, if rises in temperature continue, it may show increasing signs of stress, especially in areas not suited to its needs.

Coupled with this is the ever-present danger of the arrival here of the Spruce bark beetle and European bark beetle and this is why our Forest Service is constantly on the alert for suspect timber or packaging arriving at our docks. So far, so good.

A cornerstone of Ireland's plant health regulations is that the importation of coniferous wood with bark attached is strictly prohibited in order to prevent the introduction of a range of bark beetle and weevil pests.

A number of further import regulations are in place to prevent the entry of potentially harmful organisms. Importers of regulated material must be formally registered and a certificate must accompany imports to show they have been treated appropriately.

Oak plants in-leaf, originating in non-European countries are prohibited and most conifer plants from non-European countries are also banned.

The rules are strict and all conifer wood originating in North America must be heat-treated to 560 centigrade for 30 minutes.

Isolated conifer bark is banned and coniferous wood packing, such as pallets, crates, etc, originating from Canada, China, Japan or the US, used in the transport of commodities of all kinds, must have an approved mark verifying that the wood packing has been specially heat-treated or fumigated.

In recognition of the risk posed by wood packing it is likely that this treatment and marking requirement for wood packing will be extended to imports from other non-EU countries.

The Forest Service carries out an ongoing survey of Irish forests for injurious pests and diseases and, under current EU legislation, it is required to carry out such surveys for specific quarantine pests and diseases.

But it is an immense task with the increase in the numbers and range of imports, such as the now-popular granite from China that arrives in wood packaging and on wooden pallets.

Early detection of a newly introduced pest or disease is' of course, essential and forest owners and the forest industry should always be on the look out for possible introductions.

Irish forests are currently among the healthiest in Europe, but the regulations in force simply demonstrate the seriousness of the potential risks and the difficult task the Forest Service face in keeping alien pests at bay.

The spruce bark beetle is only about the size of a grain of rice, yet has the potential to destroy huge areas of woodland as it has done in Alaska, the home of the Sitka spruce.

This points to the need to ensure that we are not over-reliant on any one species, especially those planted in single-species blocks over large areas.

The current regulations on the establishment of woodland now insist on a mix of species, and this should help to safeguard against the wipe-out of entire plantations, if insects such as the Spruce bark beetle ever got by our defences and invaded wooded areas.

Trees are of great national benefit and we need to rapidly increase our area of woodland cover for a wide range of reasons including carbon sequestration, landscape improvement, the provision of habitats for wildlife and an increase in biodiversity across the countryside.

But trees are also an investment, providing jobs and an income for future generations. Like all investments, it is best not to have all your eggs in the one basket and the diversity provided by a mix of conifer species and broadleaves will ensure that potentially-destructive pests and diseases do not have it all their own way should they ever arrive here.

No one species is ever truly safe and with diseases such as (Phytopthera ramorum) or sudden oak death and Dutch elm disease, which is a deadly fungus spread by bark beetles, there are many existing threats to individual species.

Phytopthera P. alni can devastate alder plantations and, along with the threat of the Spruce bark beetle and the ever present deer and grey squirrels, its clear that a carefully chosen mix of species is the best insurance for the future.