Ecological Indicators 61 (2016) 676–682 Contents lists available at ScienceDirect Ecological Indicators jo ur nal ho me page: www.elsevier.com/locate/ ecolind The use of a functional approach as surrogate of Collembola species richness in European perennial crops and forests Filipa Reis a,∗,1 , Filipe Carvalho a,1 , Pedro Martins da Silva a , Sara Mendes a , Sónia A.P. Santos b , José Paulo Sousa a a Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Calc ¸ ada Martim de Freitas, 3000-456 Coimbra, Portugal b Mountain Research Centre (CIMO), School of Agriculture, Polytechnic Institute of Braganc ¸ a, PO Box 1172, 5301-855 Braganc ¸ a, Portugal a r t i c l e i n f o Article history: Received 20 April 2015 Received in revised form 30 September 2015 Accepted 5 October 2015 Available online 7 November 2015 Keywords: Community traits Functional diversity Indicator tools Biodiversity monitoring programmes Soil quality a b s t r a c t Collembolans are known indicators of soil disturbance, used in several soil biodiversity monitoring pro- grammes. As for other groups of soil microarthropods, taxonomic determination of Collembola species requires a huge effort and expert knowledge. In this study, we evaluated whether identification of Collem- bola species to the morphotype level, using an eco-morphological index which classifies individuals based on their adaptation to the soil, can be used as a surrogate of species richness in extensive monitoring schemes. The same evaluation was performed for higher taxa surrogates, using taxonomic categories at the genus and family levels. Additionally, sampling effort for perennial crops and forest systems was determined. Species data were collected from 35 sites sampled within different projects with the same number of samples (16 per site). Results showed that, on average, 8–12 samples are enough to have a good estimate of species richness for this type of systems, averaging 80–90%, but varying considerably with site habitat heterogeneity and local Collembola species pool. GLM models (using species richness as response variable) fitted for family, genus or morphotype levels (explanatory variables) were all signifi- cant (p < 0.05) but only the latter two had a pseudo R 2 higher than 0.75. This indicates that when a rapid, cost-effective assessment of Collembola richness in different sites is required, this eco-morphological trait approach, as well as the determination to the genus level, could be used. © 2015 Elsevier Ltd. All rights reserved. 1. Introduction Decline of soil biodiversity has been identified as one of the main threats to soil functioning and sustainability of natural and semi-natural ecosystems (Kibblewhite et al., 2008). Currently, some extensive monitoring schemes have been used in Europe for assessing soil quality and biodiversity, mainly in agro-ecosystems (Breure et al., 2005; Gardi et al., 2009). However, because these monitoring programmes often involve the determination of the soil organisms to the species level, they are too expensive to be used over a broad scale, across ecosystems and eco-regions, and at the desired frequency, necessary to detect deviations from species richness “normal operational range”. To overcome this caveat, several alternative approaches have been suggested to predict species richness and to monitor the spa- tial and temporal distribution of biodiversity (Cardoso et al., 2004), from which the use of surrogates to invertebrate fauna has been ∗ Corresponding author. Tel.: +351 967367738. E-mail address: ferreirareis.filipa@gmail.com (F. Reis). 1 These authors contributed equally to this work. widely discussed (Andersen, 1995; Biaggini et al., 2007; Brennan et al., 2006; Cardoso et al., 2004; Derraik et al., 2002; Duelli and Obrist, 1998; Lovell et al., 2007; Sauberer et al., 2004). Surrogacy can use different approaches: the higher taxon approach (Gaston and Williams, 1993) which is addressed in this study, environmental variables (Braithwaite et al., 1989), and species richness of indicator groups (Faith and Walker, 1996). The higher taxonomic level approach (i.e., using genus or families) is particularly advantageous for large-scale monitoring schemes, since it delivers information on a large number of taxa, while not requiring as many time and resources as a species-level identification would do (Cardoso et al., 2004; Gaston and Williams, 1993), considering that there is a smaller number of higher taxa and they are more easily identified than species. Despite the advantages of this approach, there are certain factors influencing the relationship between species richness and higher taxa richness that should not be disregarded. Andersen (1995) noted that this relationship is influenced by sampling intensity, since when the number of samples increase, more species belong- ing to higher level taxa already registered can keep being recorded. Therefore, when doing surrogacy studies, sampling effort is an important factor to take into account. Despite being essential for http://dx.doi.org/10.1016/j.ecolind.2015.10.019 1470-160X/© 2015 Elsevier Ltd. All rights reserved.