Hedgerows

Hedgerows are an important element of the wildlife, landscape and the cultural heritage of County Laois. For this reason, the Laois Heritage Office has focused on hedgerows in several projects carried out under the heritage plan. The most important of these was the survey of hedgerows in the County, carried out in 2005.

Laois Hedgerow Survey

In spring and summer 2005 field survey of hedgerows was carried out 19 sample 1 km squares distributed evenly around the county, covering approximately 1% of its total area. The focus of the survey was to record information on the extent, species composition, structure, condition, and management of hedgerows. A concurrent study was carried out in County Offaly. Laois’ hedgerow network is a huge asset to the county, valuable in terms of agriculture, landscape, wild flora and fauna, water quality, and employment. Prior to this survey, carried out in 2005, relatively little detailed information was known about the resource.

Results from the Laois survey were compared with those from Offaly and similar surveys conducted in Roscommon and Westmeath during 2004. Based on the results from the sample, the total length of hedgerow in County Laois was estimated at 12,427 km, and the average figure for hedgerow density as 7.28  kilometres per square kilometre (km/km²). This is the highest density found in any of the four county hedgerow surveys.

When compared with an earlier, more general habitat survey, hedgerow loss in Laois can be estimated at approximately 6% over the last 12 to 16 years. In Offaly hedgerow loss over the same period is estimated at 3.8% and in Westmeath at 1.1%.

A very wide range of shrub and tree species were found in Laois hedges. A total of 32 shrub and tree species, including 21 native species, were found in the hedge layer of sampled hedges. 20 tree species, including 15 native species, were recorded growing as hedgerow trees. Whitethorn is the most frequently occurring shrub species found in 98% of hedges, with ash the most common tree species, occurring in 47% of hedges.

There is very high species diversity in a high proportion of individual hedges, with almost half of hedges found to contain an average of four or more native species in a 30m strip. This is considerably higher than any other county surveyed to date. This diversity is most likely to be due to various historical, and landscape factors. Roadside and townland boundary hedges were found to contain a higher diversity of native shrub species than other hedges.

Using data analysis software, seven main hedgerow types were identified across Laois and Offaly, according to their floristic composition. The groups represent hedge types varying from species poor hawthorn hedges, through to an elm and holly group, a gorse group, and both a species rich group and a wet species rich group. The majority of Laois’ hedges occur within the context of intensive farming (i.e. improved grassland and arable land), indicating that they provide much needed habitat in intensive agricultural landscapes. A good proportion of hedges in Laois were found to link with other natural and semi-natural habitats, suggesting that they may have an important role as wildlife corridors aiding the movement of wildlife in the landscape.

Almost a third of the counties hedges have gaps for more than 10% of their length, and more than half display open, ‘scrawny’, or weak growth in the base of the hedge. These traits reduce the agricultural and wildlife value of hedges, and are not good for the long term viability of the hedges. However, Laois did record more hedges with a dense base than found in any of the other county surveys.

The majority of hedges are actively managed, with the flail by far the dominant means of trimming. The style and
standards of current trimming practices could be improved. Over a fifth of hedges are cut to less than one metre high. In terms of agricultural and environmental best practice this proportion of very low hedges in Laois should be reduced. As a result of management levels and practices, levels of flowering and fruiting were also found to be low. Trimming of roadside hedges during the prohibited cutting period of the bird nesting season was noticed, particularly around late June. Safety issues could justify the cutting, but none were apparent in most cases.

One fifth of surveyed hedges displayed clear evidence of having been laid, at least in part, in the past. This demonstrates that hedge laying was a traditional form of hedge management in Laois. Current rates of rejuvenation are not sufficient to maintain a sustainable resource, with evidence of recent laying being found in only three hedges. Laois has a particularly rich, distinct, and interesting hedgerow resource, but appropriate efforts must  be made by various bodies and individuals if the resource is to be sustained into the future.

The full hedgerows survey report can be ordered from the Heritage Office, or downloaded. A summary leaflet is also available.