Securing Biodiversity in Breckland - European Commission

Guild AnalysisA number of habitat and process categories were rarely completed or the information available wasnot sufficiently detailed to allow them to be accurately completed. For example, it was rarelypossible to differentiate between a requirement for standing versus fallen deadwood and thesewere combined prior to guild analysis. It was also not possible to differentiate between differingkinds of dung and therefore, livestock and rabbit dung were combined into one dung category. Thedistinction between a species requiring unsprayed or uncropped field margins was not possiblewith the information available and these were combined together as cultivated, arable margins.Using the habitat matrix, completed for 2149 Breckland conservation priority species, habitats andprocesses with values of +2, +3, -2 and -3 were selected and used to create a list keywords (usuallybetween three and six words) for each species. These were then used to group species withidentical keywords to form initial guilds of species with the same requirement. This allowed theimmediate identification of a number of important guilds:1) Species for which our information indicated a requirement only for one of the following:woodland, open woodland, veteran trees, wetland, standing water or running water. Thesewere assigned to a guild of the appropriate name, e.g. woodland. Generally, these werespecies for which current ecological knowledge is limited.2) Species that had one essential requirement e.g. dung or deadwood, but that are notecotone specific.3) Species that occur in a range of ecotones were assigned as such, e.g. open and woodlandecotone and open, woodland, wetland ecotone.The remaining species (approximately 86% of the total number) were classified into one of sixbroad ecotones; open, open with scrub, open woodland, woodland, wetland, wet woodland. Withinthese broad ecotones the requirements of species for disturbance and grazing was assessed andguilds were formulated based on these options.Guilds were formulated independently of normal habitat associations (e.g. dune, brownfield etc.).However, information on ecological structures and micro-habitat requirements were used to informguilds. For example, species of arable or brownfield habitats but that were not recorded from anyhabitats likely to experience grazing, i.e. not recorded from lowland heathland, calcareousgrassland or sand dune, unless otherwise known, were taken to have a requirement for disturbancein the absence of grazing. They were therefore, assigned to a disturbance-no/light grazing guild.Similarly, species that occur in grassland were taken to require some intensity of grazing.Detailed and specific information on species requirements for grazing and disturbance wasavailable for almost no species. However, it was possible to assess the needs and tolerances ofmany species in relation to high and low levels of grazing and disturbance. Where there wasuncertainty regarding responses to important ecological processes such as grazing or disturbance,then species were retained within a general guild for their key habitat type.Species assigned to standing water and running water guilds are mostly aquatic or semi-aquatic forall or part of their lifecycle. Species assigned to the littoral guild may be either largely aquatic orterrestrial but occupy similar habitats, often related to fluctuating water bodies. Species requiringplant stems, seeds or flower-heads were assigned to guilds without or with limited grazing.69