The response of Orthoptera to grazing on flood defense embankments in Europe

Kimberley Fargeaud,Tim Gardiner

doi:10.3897/jor.27.25183

Abstract

European flood defense embankments form an excellent habitat for Orthoptera. To be effective against storms, these vegetated earth embankments have to be managed by grazing or mowing. However, grazing can impact invertebrates such as grasshoppers and crickets (Orthoptera). This management can lead to dispersal toward undisturbed grassland and reductions in the quality of habitat, food resources and oviposition sites. In most cases, orthopteran insects require heterogeneous vegetation patches with swards of varying height. The impact of grazing depends on the type of livestock; it is very important to choose appropriate animals, timing and intensity. Sheep grazing in late summer (September-October) at a moderate intensity seems to be favorable for Orthoptera. If grazing is carefully monitored, it can promote Orthoptera conservation while maintaining flood defense integrity.

Highlights

In Europe, coastlands are protected from tidal flooding by vegetated earth embankments known as ‘dikes’ or ‘dykes’ (Verheij et al 1997, Sprangers 1999)
We investigate how flood defense management and Orthoptera conservation can be balanced in Europe by collating the available literature and assessing its implications
Flood defense embankments in Europe are commonly rich in Orthoptera

Summary

Introduction

In Europe, coastlands are protected from tidal flooding by vegetated earth embankments known as ‘dikes’ or ‘dykes’ (Verheij et al 1997, Sprangers 1999). A small-scale study in Essex suggested that the absence of intensive agriculture and livestock grazing on an island with sea wall flood defenses created important refuges for Orthoptera (Gardiner and Ringwood 2010). Intense cattle grazing can damage the soil surface (Fig. 5) and the flood defense requiring costly repairs For this reason, these grazers are not generally recommended for grazing dikes or sea walls (Gardiner et al 2015). They found a significant cumulative effect; an increase in sheep grazing intensity caused decreases in insect abundance, diversity and species richness Regarding cattle, their presence on sea walls can create very short, homogeneous grassland swards (uniformly

58 Mixed management

Findings

Conclusion