scope:

This part of ISO 23611 specifies a method for sampling and handling free-living nematodes from terrestrial field soils as a prerequisite for using them as bio-indicators (e. g. to assess the quality of a soil as a habitat for organisms). The sampling design of field studies in general is specified in ISO 10381-1. Methods for some other soil organism groups like earthworms or collembolans are covered in other parts of ISO 23611. Nematodes occur in high numbers [(5 000 to 100 000)/kg fresh soil] and high (20 to 100) species diversity in almost every soil sample. Moreover, there is a broad ecological spectrum of feeding types and food web relations among the nematodes such as bacterivores, fungivores, herbivores, predators and omnivores [26], [27]. These factors make the group highly suitable as indicators for ecological soil quality, but standardisation of methods is urgently needed for comparison and combination of results. This part of ISO 23611 applies to all terrestrial biotopes in which nematodes occur. The nematodes that are characterized by the proposed procedure are all the free-living forms of nematodes found in soil. They include non-plant feeding nematodes, as well as ectoparasitic plant-feeding nematodes and free-living stage of endoparasitic nematodes. The quantification of obligate plant-feeding nematode in roots requires specific methods. NOTE 1 Basic information on the ecology of nematodes and their use as bio-indicators can be found in the bibliography. NOTE 2 When sampling soil invertebrates it is highly recommended to characterise the site pedologically because there is a strong relation between the occurrence of certain species and abiotic factors. However, such a characterisation is not covered by this part of ISO 23611. Especially pH, grain size distribution, bulk density, C/N ratio, organic carbon content and water holding capacity should be measured by using ISO 10390, ISO 10694, ISO 11272, ISO 11274, ISO 11277, ISO 11461 and ISO 11465.