Codes: I - IA - IB - IG - IM - IS - IT
Site types that use this protocol: Terrestrial
The invertebrates form a large group in terms of species richness and many of them pose difficult problems for long-term monitoring: sampling for many groups is labour intensive, identification difficult, time-consuming and therefore expensive. However, some groups are ubiquitous, are more readily sampled and identified, and are known to respond to changes in climate, pollution and land use (eg Luff & Woiwod 1995); moreover, in some cases there are already good biological, physiological or ecological data, often from long-term studies, which can provide a background to interpretation. A general policy in considering suitable invertebrate groups for ECN sampling has been to concentrate principally on indicator groups rather than on individual species, and wherever possible on groups where monitoring schemes already exist. It was desirable to include examples of both herbivores and predators, as well as some populations exhibiting genetic variation, particularly where an environmental link is known. Practical considerations of the availability of expertise and of other resources have also been taken into account so that as wide a range of invertebrates as possible is being sampled within the resources likely to be available within the ECN programme.
The invertebrates protocol covers butterflies, ground predators (carabid beetles), moths, spiders, spittle bugs and tipulids (crane flies).
Butterflies are one of the easier insect groups to identify and monitor and are known to respond rapidly to changes in vegetation abundance and quality. The Protocol adopted by ECN is that already in use for the national Butterfly Monitoring Scheme, operated jointly by the Centre for Ecology & Hydrology and the Joint Nature Conservation Committee and organised by the Biological Records Centre. This existing scheme provides a strong background of information for comparison with ECN data.
Weekly monitoring along transects is conducted, based on UK Butterfly Monitoring Scheme methodology.
View IB protocol [PDF]
Ground predators (carabid beetles)
The ground beetles (Carabidae) are a group of predatory invertebrates. They are monitored by ECN because they might amplify changes in their prey or respond differently to environmental change from butterflies and moths. Pitfall trapping has been used extensively and successfully for this group, and a well-developed protocol already exists. Even though it is known that problems exist in interpreting data from such traps, active programmes of standardisation are in progress. Analyses of existing data have shown that carabids can be sensitive indicators of changes in management. Many beetle species are known to be sensitive to temperature changes.
Two-weekly sampling using pitfall traps is conducted.
View IG protocol [PDF]
The Lepidoptera (butterflies and moths) is a large order of insects and is among the best known, both taxonomically and biologically. They are a good indicator group for environmental change. The moth protocol involves sampling by light trap of all the large moths (macrolepidoptera) using the methodology of the Rothamsted Insect Survey. This provides a strong background of expertise to ensure that the Protocol requirements are met, as well as an existing extensive national database which forms the basis for analysing future trends in populations.
Counts by species, collected nightly (weekly at remote sites), are made using the methodology of the Rothamsted Insect Survey.
View IM protocol [PDF]
Spiders are large diverse predatory taxonomic group with an important ecological role in the UK. The ECN Ground Beetle protocol uses pitfall traps that also efficiently trap spiders. The identification and counting of these spiders therefore represents a cost-effective way of extending the range of invertebrates monitored.
View IA protocol [PDF]
Two species of spittle bug, Philaenus spumarius and Neophilaenus lineatus, are both widespread and common throughout the United Kingdom. Their nymphs, which are xylem feeders, are surrounded by a mass of froth or spittle which the nymphs produce by forcing air into a fluid exuded from the anus. As well as providing some protection from predators, the presence of the spittle makes the nymphs visible and therefore relatively easy to sample. There is a solid background of published ecological work on these species both at lowland and at upland sites. In addition to estimating an index of nymph density, the Protocol involves the sampling of colour morphs of P. spumarius adults. The colour polymorphism is mainly determined by a series of closely linked genes; it is likely that the proportions of morphs are environmentally determined and are therefore good indicators of environmental change.
Nymph density and adult colour morphs assessed annually.
Two-weekly sampling using pitfall traps is conducted.
View IS protocol [PDF]
Tipulids (crane flies)
The larvae of craneflies (Tipulidae) are widespread, numerous and easily sampled in soil. They are rarely, if ever, found at depths below 10 cm and sampling does not involve the degree of soil disturbance which would be incurred, for instance, in sampling earthworms. These larvae are mainly plant feeders; they are important food for many other animals and play a key role in terrestrial food webs. Because several species might be present, estimates of changes of abundance will be possible on a comparative basis. To ensure that sampling covers the latter, larger larval stages, for which both retrieval and identification are easier, it is necessary to sample both in spring and in autumn because, although most species have an annual life cycle, they have different emergence seasons.
Tipulid larvae are extracted from soil cores April and September. Note that more recently we have also been recording adult tipulids collected in moth traps at most ECN terrestrial sites.
View IT protocol [PDF]