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East Mendip Hedgerow Project (EMHP)

The EMHP set itself several objectives based upon surveys to increase the knowledge of hedgerows within East Mendip and to raise public awareness of the importance of hedges to both the community and quarrying industry. The Project was jointly funded by the Somerset Aggregates Levy Sustainability Fund and the Somerset Minerals Forum (Mendip Quarry Producers).

Over 2000 hedges were surveyed at reconnaissance scale to determine their management type, historical features and woody species content. A further 100 hedges were re-surveyed later in late summer to determine their value as important hedges in terms of the Hedgerow Regulations and to log their ground flora. Ten of those hedges with different management regimes are currently being investigated for their small mammal and invertebrate populations.

Four Parish exhibitions, a hedge competition and a hedge laying course were held to show the results to the general public, or elicit community involvement.

The surveys revealed that a significant proportion of the areas hedges are in management decline, especially mature (taller) hedges. The greatest need for targeted advice in this respect was in the eastern half of the study area. Perhaps surprisingly, hedges that were regularly trimmed proved to be the most species-rich and historical features in these were better protected. Almost 1 in 20 hedges have been lost since 1970, outstripping new planting. Hedges in the west of the survey area were less species-rich than in the east, and hedges bordering old lanes and roads were the most species-rich of all. About 70% of the hedges would be regarded as "important hedgerows" in terms of the Hedgerow Regulations.

More community involvement is planned in early 2005 with a further exhibition, two "hedges and history" walks, and hedge planting/laying events.

Graham Colborne and Francesca Lemon (FWAG)

Overwintering macro-invertebrates in the bases of six East Mendip hedgerows - Winter 2004-5
Jon Marshall and Trevor West (Marshall Agroecology Ltd)

Six hedgerows in the East Mendip area, representing mature or untrimmed hedges with a woody species component that was either species-rich, species-poor or gappy, were selected for sampling. The aim of the study was to characterise the diversity of overwintering fauna in the hedgerow bases. These hedges represent the main hedgerow types identified by extensive surveys as part of the East Mendip Hedge Project. Each hedge was divided into three lengths and the macroinvertebrate fauna sampled at three locations in each length. Samples were bulked for sorting and identification. A Vortis vacuum sampler was first used to catch surface invertebrates in a 10cm diameter area, which was then soil cored to a depth of approximately 10cm. Samples were stored and then sorted. Vortis samples were sorted under a binocular microscope, while soil samples were washed through brass sieves and material retained by 420µm mesh was sorted by eye. Animals were identified to major groups under a binocular microscope and the data analysed using formal Analysis of Variance and Principal Component Analysis.

The results show that all the hedges supported significant numbers of invertebrates in the winter. Hedgerows are therefore significant winter habitats. Analyses demonstrated significant adverse effects of trimming on the abundances of a number of faunal groups, notably adult beetles and beetle and fly larvae. Diversity of invertebrates was greatest, on average, in hedges rich in woody species and lowest in gappy hedges. Faunal communities were very similar in all trimmed hedges and in the gappy, untrimmed hedge. Structure and management of these hedges may combine to create similar invertebrate communities. Nevertheless, the impacts of local management on the herbaceous component of hedges should not be overlooked, as invertebrate diversity is reported as being closely linked to herbaceous flora diversity. As part of a strategy for developing farm wildlife conservation, gappy hedges should be avoided and mature, stock-proof hedges that are rich in woody species should be encouraged.