Collembola eco-morphological indices (EMI) and Soil Biological Quality Index (QBS-c): a review and practical guidelines for soil health assessment

Martina Coletta, Antonietta La Terza, Stefan Scheu, Ting-Wen Chen 

Soil health assessments remain dominated by physicochemical indicators, largely due to limited functional understanding and a lack of practical tools for quantifying soil biodiversity in applied contexts. However, many soil functions are fundamentally driven by biotic components, highlighting the need for robust biological indicators. The Soil Biological Quality indices, QBS-ar and QBS-c (Parisi, 2001; Parisi et al., 2005), offer simple, direct approaches. While QBS-ar considers the entire soil (micro)arthropod community, QBS-c focuses on Collembola, assigning taxa eco-morphological index (EMI) scores based on their adaptation to soil. We reviewed 24 studies using Collembola-based QBS-c and EMI methods to evaluate their development and application over the past two decades. Our synthesis reveals substantial inconsistency in EMI assignment, with the widely cited framework of Vandewalle et al. (2010) both expanding EMI use beyond Italy and modifying Parisi’s original trait definitions and scoring schemes. We systematically compared trait selection, scoring approaches, and methods for aggregating species-level EMIs into community-level indices. Principal component analysis of Parisi’s genus–trait matrix showed strong correlations among antenna, furca, and leg traits, and among ommatidia, pigmentation, and cuticle traits, while body size was largely independent. To improve applicability in soil monitoring, we propose a standardized QBS-c protocol featuring: (i) a minimal trait set (body size, pigmentation, furca), (ii) EMI scoring schemes aligned with the original euedaphic gradient, and (iii) a flexible community-weighting framework incorporating both presence–absence and abundance data. These recommendations aim to enhance comparability across studies and usability for non-specialists, facilitating broader integration into soil monitoring programs.