Standardized Protocols for Soil Fauna Extraction and a Call for Cross-Lab Implementation

Area of Science:

• Soil ecology
• Biodiversity science
• Invertebrate zoology

Background:

• Global soil invertebrate diversity assessment is hindered by non-standardized extraction methods across laboratories.
• Lack of commonly accepted, openly available, and well-documented protocols limits data comparability for soil fauna.
• Soil and litter invertebrate diversity studies require consistent methodologies for accurate global trend analysis.

Purpose of the Study:

• To present harmonized, expert-assembled methodologies for extracting key soil and litter invertebrates.
• To provide practical guidance, including 'expert tips,' to enhance extraction efficiency and reproducibility.
• To facilitate global comparisons of soil animal data for better biodiversity understanding.

Main Methods:

• Development of harmonized extraction protocols for nematodes, enchytraeids, microarthropods, and larger invertebrates.
• Inclusion of visual aids (images, videos) and troubleshooting advice for practical application.
• Pilot experiments testing nematode wet extraction filter layers and heat extraction efficiency for large soil animals.

Main Results:

• Two layers of milk filters in nematode extraction showed similar efficiency and sample cleanliness compared to one.
• Heat extraction captured an average of 31.3% of large soil animals (≥3mm) missed during manual sorting.
• Significant differences in large soil animal extraction efficiency were observed across three distinct laboratories.

Conclusions:

• The presented open-access protocols standardize soil invertebrate assessment for ecological studies worldwide.
• Harmonized methods are essential for accurate global comparisons of soil biodiversity distribution and dynamics.
• Further standardized testing of extraction efficiency for large soil animals across regions and research groups is recommended.