The heavy rainfall and resulting flooding and erosion of Saturday August 16 suggests that Northern Ireland is ill-prepared for the wet conditions that will likely get worse with climate change. Along with measures such as 'balancing lakes' (as at Craigavon), the creation of secondary 'relief' river channels, construction of flood-walls and other engineering works, fundamental alterations will have to be made to river catchments, the land onto which the river-filling rain falls.

Rural Northern Ireland – if not Ireland as a whole – needs a newly designed landscape with a well-distributed, high proportion of trees. In comparison, mainland Europe has an average 30% tree cover, whereas Northern Ireland has a pitiful 1%, most of it comprising hedgerow trees. With an increased and widely-distributed tree cover, trees and tree-roots will slow down the movement of water over the land: it will not become wet and flooded to the same extent and, on the macro-scale, trees will add reservoir capacity to farmland and the extremes of 'trickle' and 'spate' that characterise Irish rivers will be 'evened-out'.

Trees have many (about 12) functions and benefits that will greatly benefit the environment and agricultural systems. Shelter-belt planting will significantly increase the amount and distribution of trees; an increase in the proportion of trees will introduce diversity into the agro-ecosystem and enhance its sustainability. Related to rainfall, increased tree cover will add to the 'reservoir capacity' of the land and slow down the run-off of water into rivers. In well-treed landscapes, flooding is less likely during periods of heavy rain. The greater the tree cover, the less water will enter watercourses and cause flooding: a study has shown that, in woodlands, during the growing season, almost 40% of rainwater is evapo-transpired back into the atmosphere, never reaching river channels; other rain-relevant benefits are the reduction of erosion and the capture of fertilisers/pollution prevention. By their roots, trees literally hold the soil together limiting soil loss and preventing mudslides; along river valleys, untimely-applied fertilisers can be intercepted by tree roots and the pollution of water bodies can be limited.

Richard St Barbe Baker (1889-1980), a former British colonial forester who founded 'Men of the Trees' (now International Tree Foundation') among native Kenyans in the 1920s, also favoured shelterbelts although he was possibly over-optimistic as to their efficacy "... By devoting 22% of the farm to trees, output could be doubled. Trees create microclimates, reduce wind-speed, lift the water table and increase the population of worms."

In the British Isles, the 'patchwork quilt'/hedged fields that are a vestige of the 18th and 19th centuries, have been enlarged, particularly post World War 2. Proposals for increased tree cover could utilise this landscape by planting in the larger fields and paralleling north-south hedges with belts of trees and shrubs, to equalise the shade. The interception of the prevailing south-westerly winds will reduce wind-chill, raise the temperature of the microclimate (for a downwind distance of 10x the shelterbelt's height) and increase the yield, both pastoral and arable, by between 25-50%.

In Britain and Northern Ireland, the shelterbelt planting described could be financed by the present 'Farm Woodland Premium Grant Scheme' (FWPGS) providing grants to plant 'woodlands' of at least one hectare per farm, in blocks of min 20 metres width and 0.2 ha in area (a shelterbelt of 20 x 100 metres = 0.2 ha). The farmer also receives an annual payment, comparable to a conacre rent, for 15 years. Well within that time, increased yields will be realised, so it will be a 'win-win' situation. To achieve this 'woodland planting' to the great extent required to impact on considerable areas, it may be necessary for DARD to further encourage it by modifying the FWPGS area requirements and increasing the level of grant. DARD will no doubt need to exercise aesthetic considerations, in overview.

Malcolm Lake

International Tree Foundation

Northern Ireland Branch