Isolation of habitat patches limits colonisation by moorland Hemiptera

There has been a significant loss in the UK, and elsewhere in Europe, of moorland dominated by heather Calluna vulgaris. One response to this has been the initiation of moorland vegetation restoration projects. Heather moorland has distinct assemblages of invertebrates and the ability of these to colonise newly created habitat patches has not previously been experimentally tested. We established a dispersal and colonisation experiment by transplanting C. vulgaris-dominated turfs within grassland at different distances (up to 40 m) from heather moorland vegetation. Hemiptera were cleared from these turfs by the use of an insecticide and were sampled 1 year later to investigate re-colonisation rates. Hemiptera assemblages on transplanted turfs were most dissimilar to those of heather moor at the greatest distances of these turfs from heather moor. Colonisation rates of heathland-indicator Hemiptera declined exponentially with distance. The number of individual heathland-indicator Hemiptera was higher on turfs 5 and 10 m from heather moor than on turfs transplanted back into the heather moor, possibly due to a crowding effect. Our findings indicate that moorland Hemiptera assemblages may be limited by dispersal ability. We recommend that moorland restoration schemes should be prioritised on ground as close as possible to existing heather moors.