Introduction Collembola (springtails) are not a well-known group because of their small size and cryptic habits. They are, however, extremely abundant and widespread, being the most numerous and diverse arthropods in soils and leaf litter after mites and, in some situations, outnumbering them. Taxonomically, the Collembola are a class of arthropods that are morphologically similar to insects in gross body structure, but different in the lack of a hard exoskeleton and wings, in the presence of internal mouthparts and in possessing, primitively, only a few simple eyes on each side of the head and a jumping organ located ventrally. These differences make their collection and treatment taxonomically often quite different from insects. As detritivores, Collembola play an important role in the decomposition of dead plant material and in nutrient cycling. They are generally considered to be beneficial organisms as few species feed on live plants (Hopkin 1997). Average densities in soil are between 5000 and 30000 per m 2 , rarely reaching close to 100000 per m 2 , and there could be up to 50 species in each square metre (Table 1) (Greenslade 1993). As well as being common under stones, in soil, humus and the leaf litter layer, these animals may also be found above the ground on grasses, under bark on trees, on flowers and leaves in tree canopies and on shrubs and in rotting timber. They occur in extreme habitats such as caves and on the seashore. As these animals are so widespread and abundant, occurring from polar regions to arid and tropical regions, their influence in ecosystem functioning is considerable. The Australian fauna is not well known. About 400 species are described; a further ~1000 are known but not described. The fauna probably consists of more than 2000 species (Greenslade 1994a). Australian endemism is high at ~80% and local endemism is significant in some groups. In addition to the indigenous fauna, there is a substantial group of introduced, exotic organisms that were probably imported with soil, plants and stock, mainly from Europe, during the early days of European settlement. Any bioindicator that can easily and rapidly measure the effects of impacts may contribute to management of the ecosystem to improve sustainability. Impacts are those factors that are deleterious to the ecological sustainability of ecosystems. In this paper, I first highlight the characteristics of springtails that have made them useful as indicators for the effects of a range of natural and human induced impacts to the environment, second, critically describe methods of collection, including a protocol for an intensive survey of the fauna, and third, describe field work in Australia where they have proved of value in measuring the effects of environmental impacts. Collembola as an indicator group To be useful in measuring environmental change, an indicator must provide measurable and repeatable information in response to whatever question is being posed about the environment more rapidly than would be obtained by a superficial visual inspection. Ideally, it should also be able to predict trends, by responding linearly to the impact being studied. Over the last 20 years or so, authors of several papers have listed the general characteristics of an ecological indicator (Majer 1983; Greenslade and Greenslade 1984; Andersen 1999; Büchs 2003b). Andersen (1999) focuses on the problems of selection and validation, and while Büchs’ (2003b) treatment is thorough, this author gives no examples of Collembola and concentrates on European examples of other invertebrates. All authors have stressed that the main traits required in an indicator taxon are sensitivity, responsiveness, ubiquity, being functionally important in ecosystems and representative, that is being able to act as a surrogate for other taxa, as well being easy to sample, identify and analyse. A range of invertebrates has been proposed as indicators for Australia (Neville and Yen 2007; New 2007). The Collembola are one such group, together with ants, mites, herbivorous bugs, spiders and carabids. As might be expected, no single group is ideal for all situations, but the Collembola have proven to be a robust indicator in a range of ecosystems in Australia if certain parameters such as the appropriate collecting method and level of identification, are applied correctly. Collembola are present in all ecosystems, are 0816-1089/07/040424 10.1071/EA05264 © CSIRO 2007 Penelope Greenslade Department of Botany and Zoology, Australian National University, Canberra, ACT 0200, Australia. Email: penny.greenslade@anu.edu.au Abstract. Collembola have been used to assess the ecological status of a range of ecosystems in Australia over the last 35 years. The traits that Collembola possess that make them valuable as ecological indicators are listed. Examples of situations where they have been used to measure impacts in mainly agricultural landscapes are described and the contributions the results have made to management for ecological sustainability are noted. Densities of exotic and native species in a variety of ecosystems are provided and a list of genera with exotic species in Australia is given. A protocol for comprehensively surveying Collembola is described and a critique of different methods given. The potential of Collembola to act as indicators of landscape stress in Australia Australian Journal of Experimental Agriculture, 2007, 47, 424–434 www.publish.csiro.au/journals/ajea CSIRO PUBLISHING