GRASSHOPPERS OF THE SANDLING HEATHLANDS
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GRASSHOPPERS OF THE SANDLING HEATHLANDS TIM GARDINER Introduction There has been a National Vegetation Classification (NVC) system for plants in Britain for over two decades. The NVC is split into several volumes, each one dealing with specific habitats (e.g. grasslands, heathlands and mires, and woodlands and scrub). It is possible to compare survey data collecting using standardised NVC methodology with the specific plant community in the respective volume. It is then possible to identify if the particular plant community is of particular conservation interest due to its rarity. NVC plant communities may indicate specific geology and soil types, knowing this helps to target conservation management to preserve the most important plant communities. Having a system to classify grasshopper assemblages of importance may be a useful tool to identify the most valuable sites for nature conservation in Britain. In theory, it should be relatively easy to record the grasshoppers present across a range of sites in the same general habitat and then see if there are clear similarities between different types of lowland heathlands for example. Different grasshopper species have contrasting microclimatic preferences which may drive the diversity of assemblages. Short grassland and heathland swards may be unfavourable for grasshoppers due to high microclimatic temperatures (>44oC), which can lead to shade-seeking behaviour and vigorous escape responses in several grasshopper species (Uvarov 1966; Willott 1997). The optimum air temperature for development of grasshoppers in the UK is thought to be 35–40oC (Willott, 1997). Responses to microclimatic temperatures may differ between species (Gardiner & Hassall, 2009), for example, the mottled grasshopper Myrmeleotettix maculatus is a short sward specialist and its small size may be an adaptation for the high temperatures it experiences (Willott, 1997). Contrastingly, the common green grasshopper Omocestus viridulus, a long grass species in the UK, is a large insect which may overheat in short, hot grasslands/heathlands and it therefore avoids those habitats (Willott, 1997). The Sandlings are an area of coastal sands which stretch from Ipswich in Suffolk all the way north to Belton and Waveney Forest in east Norfolk. The Sandlings contain remnants of lowland heathland, approximately 1681 ha or 8% of once extensive heaths. From 1932–1983 losses of Sandling heaths were high, with 83% disappearing due mainly to afforestation (30%) and agriculture (30%). There are 42 Sandling heaths remaining, therefore, protection of these sites and their grasshopper assemblages is of paramount importance. Succession of open heathland to scrub and woodland is the current threat to the grasshoppers of open habitats, but recreational pressure, overgrazing and summer fires are also a problem. Heathlands are an outstanding habitat for Orthoptera and identifying assemblages will aid the conservation of this important resource on the Sandlings. The small-scale study described here concentrates on surveys of the Sandling heathlands in Suffolk and east Norfolk in an attempt to classify their grasshopper (Orthoptera: Acrididae) assemblages.
Trans. Suffolk Nat. Soc. 49 (2013)