The Farm Forest

-The current emphasis on biodiversity or nature conservation arises from global concerns for the quality of our environment. The word “biodiversity” is a combination of the words “biological” and “diversity”, and refers to the range of plant and animal species that live on this planet.

Nowadays, landowners, foresters and agriculturalists are encouraged to incorporate the principles of nature conservation into their commercial activities. We all have a role to play in finding out how this can best be done. In July 2000, the Forest Service published guidelines on forestry and biodiversity in response to international Directives and Agreements, and in 2002, the Dept. of Arts, Heritage, Gaeltacht and the Islands published the National Biodiversity Plan, which sets out how each sector can contribute to nature conservation.

While afforestation of our countryside has been controversial in some aspects of nature conservation, there can be little doubt that the expansion of forests and woodland has many potential benefits for wildlife. Establishing a forest on farmland can be a very positive move, from an environmental point of view. The environmental benefits obtained depend largely on how and where the afforestation is carried out – and this ultimately depends to a large extent on decisions made by the landowner. There is much that landowners can do, at all stages of the process of forest planning and management, to enhance the value of their plantation for the benefit of plant and animal species, i.e. to improve the “habitat value” of their forest.

It is important to start out with a good assessment of your afforestation site. This assessment will tell you what areas you should aim to retain unplanted and incorporate into your overall forest design as “open space”, and what “biodiversity features” should be retained and protected during forestry operations.

Start by asking yourself: What habitats are currently present on the site? Is there semi-natural habitat or is it all improved agricultural grassland? Examples of semi-natural habitats include: wet intact raised or blanket bog, partially cutover bog, any kind of wetland (e.g. swamp, marsh, fen), heath, unimproved grassland, native woodland or scrub, and coastal dunes or saltmarsh.

If your site consists mostly of semi-natural habitats, then planting is generally not a good idea – it may result in an overall decrease in biodiversity, which is an unwanted result. There is potential conflict here because there is a strong tendency to locate forest plantations on land that is marginal for agriculture. However, of all areas on the farm, it is this marginal land that often has the best habitat value, and this can be lost by establishing a commercial crop of trees. It may seem controversial to locate your plantation on good agricultural grassland, but by doing so, you are not only increasing the potential productivity of your forest tree species, you are also often moving from a situation where you may cause loss of biodiversity to one in which you are enhancing biodiversity overall.

Unplanted Areas
If, on the other hand, your site has only small pockets of semi-natural habitat present, aim to retain these as unplanted areas (retained habitats) in your overall forest design. Give them good, unplanted buffer zones, to limit the effects of shading by mature trees in future.

Under the Forest Service Biodiversity Guidelines, five to ten per cent of a grant-aided site can comprise retained habitats.

Map out for retention and protection any features of nature conservation value on the site (we refer to these as biodiversity features). Examples of biodiversity features include: over-mature trees – any old trees present in or around the site should be retained and allowed to die off and decay naturally, to provide important habitat for plants and insects; large, old hedgerows – these frequently support a range of native woodland plants; streams or rivers – these should be given a non-intervention buffer zone on either side, in which you should aim to have a patchwork of open space and native broadleaves, as the site permits. You may also have features that are important for particular species (e.g. heronries, badger setts, important plant sites) which should be retained and managed with protection of that species in mind.

Species & Biodiversity
Selection of which species to plant is a decision that is as important to nature conservation as it is to commercial aspects of forest planning. There is a rule-of-thumb in commercial forestry which says you should plant the “right trees in the right place”. This rule also applies when you are trying to improve the ecological value of your forest. The problem is that the species which have the most to offer nature conservation may not always give the best economic return, and so species selection is a question of achieving a balance between commercial and ecological considerations. Broadleaved tree species tend to have better habitat value than conifers, and native broadleaf species yield the best habitat value of all (e.g. willows and birch), but many of our native species are not considered to be good commercial timber-producers.

There are several potential compromise solutions. For maximum ecological benefit, you should incorporate as many species into your forest design as possible, balancing this with commercial considerations.

Having selected your primary commercial species, incorporate a range of minor species into the forest design.

Where there is no realistic prospect of a commercial return from minor species (e.g. too small an area involved), select non-commercial native broadleaf species as minor species. In any situation where you are planting for non-commercial reasons, your planting material should always be native species of local or native provenance, and you should select species that are ecologically suited to the site. Adopt a tolerant approach to natural regeneration of minor species over the lifetime of the crop, where it doesn’t hamper the timber production aspects of forest management.

Management & Biodiversity
As your plantation matures, all of the management decisions you make have a bearing on nature conservation. Thinning the stand is beneficial to the ground flora beneath the trees, as it increases light penetration to the forest floor. Avoid unnecessary “tidying up” – leave dying trees and dead wood on site. The much-maligned ivy that often clothes mature trees in hedgerows and woodlands offers shelter and berries to birds in winter, and should not be cut. Take care to avoid damage by machinery to open spaces within the forest. Aim to reduce the use of chemicals to the minimum required. If possible, schedule forestry operations for the autumn/winter months, to avoid disturbing nesting birds.

With some careful thought and planning, we can improve the habitat quality of our forests, which in turn improves the lot of the animals and plants that depend on them.