Knowledge of the magnitude, distribution and structure of biological communities is essential for our understanding of ecosystem processes and their response to impacts, and is thus critical for the development of effective management strategies. Soil fauna, composed of abundant minute and wingless species characterised by generalised low dispersal capacity and strict niche requirements, are a functionally important but vulnerable component of biodiversity. Despite the known importance of soil biodiversity, our knowledge is extremely poor, and at the community level almost non-existent. Soil biodiversity is considered one of the last 'biotic frontiers' together with rainforest canopy biodiversity, and the biodiversity of deep seas. Three of the most abundant and diverse groups of arthropods in the soil - beetles, springtails and mites, are essential for functional soil processes, such as the decomposition and mineralisation of organic matter and nutrient cycling. To preserve and maintain fundamental soil ecosystem processes, it is essential to first understand the vulnerability of soil communities under ongoing global change, something that first requires the characterisation of community composition and structure.
Logistical difficulties for the identification and quantification of soil arthropods from a single standard soil sample arise from the very high numbers of individuals (up to 100,000 per m2 of soil), and the typically cryptic nature of species boundaries. However, recent technical advances provide a tool to bridge this knowledge gap. In recent years high throughput DNA sequencing (HTS) has been harnessed to quantify the microbial diversity of ecosystems and is now revolutionizing the study of complex and hyperdiverse macroscopic communities. Now, for the first time, we can obtain quantitative measures of the mesofaunal biodiversity of soil, and its spatial structure and functional dimension, through the application of tailored 'metabarcoding' and 'mitochondrial metagenomics' protocols. SOILBIODIV applied these novel HTS techniques to develop new molecular protocols within a multidisciplinary project for the characterization of soil arthropod communities (beetles, springtails and mites) in an insular setting of the Canary Islands.
The main objectives of SOILBIODIV were (1) Develop and validate an interdisciplinary metabarcoding and mitochondrial metagenomics pipeline for robust measures of invertebrate soil biodiversity, applicable across all spatial scales; and (2) characterize soil arthropod mesofauna richness, community structure and turnover within and among ecosystems and islands, identify introduced species and associated biodiversity risks.
Data generated within SOILBIODIV allows for the estimation of community responses and vulnerability of soil invertebrate biodiversity to (i) climate change and (ii) invasive species, two important drivers of global change. Resources and results generated in SOILBIODIV will be very relevant for (i) the European Initiative BEST (Biodiversity and Ecosystem Services in Territories), (ii) the new International Platform IPBE (Intergovernmental Platform on Biodiversity & Ecosystem Services), (iii) the Strategic Objective C of the Strategic Plan for the Biological Diversity 2011-2020 (Aichi Targets www.cbd.int) and for (iv) the quantification and control of biodiversity loss under climate change on Special Territories of the European Union (ORs and OCTs) as highlighted by the recent International Conference on Biodiversity and Climate Change (October 2014, see www.cbd.int).
