EDAPHOLOG monitoring system: automatic, real-time detection of soil microarthropods

Summary Soil microarthropods as organic matter decomposers play an important role in soil functioning thus providing ecosystem services. However, ecosystem scale investigations on their abundance and dynamics are scarce because their high spatio-temporal heterogeneity requires huge sample size. Processing and identifying large number of individuals is extremely labour intensive. We prototyped a device called EDAPHOLOG monitoring system that consists of (1) a probe that catches and detects microarthropods and estimates their body size; (2) a data logger transmitting data to a central database, and (3) a Java application for retrieving data. We tested the device in three ways. First, we tested the precision and accuracy of detection and body size estimation of the device in the laboratory using microarthropods of five morphotypes: euedaphic Collembola, haired Collembola, scaled Collembola, Acari and Oribatida. Second, we compared the number of individuals collected by EDAPHOLOG traps, pitfall traps and soil extraction method in an alfalfa field. Third, we deployed a total of 100 EDAPHOLOG probes in nine different habitats for over three months to demonstrate the applicability of the monitoring system. In the laboratory, EDAPHOLOG detected 95.6% of individuals; even the smallest morphotype (Oribatida, body size (mean±SE): 0.58±0.04 mm) were detected in 87.5% of cases. For body length estimation we established a quadratic relationship between the estimated and measured body lengths, however, the R2 of the quadratic model was only 0.32. By comparing the three different sampling methods (EDAPHOLOG, pitfall traps and soil extraction), we concluded that EDAPHOLOG traps better select for soil microarthropods compared to classical pitfall traps, since the latter ones caught also many other arthropod species. Furthermore, the EDAPHOLOG traps caught more epigeic microarthropods and almost the same number of soil-dwelling euedaphic microarthropods as the numbers collected by soil extraction. During the three month-long field test the total numbers of detected and captured individuals agreed very well, although the device tended to overestimate the number probably due to counting also some soil particles falling into the probe. This trend was the same regardless of the total number caught. Surface-dwelling epigeic and litter-dwelling hemiedaphic microarthropods dominated the samples although soil-dwelling euedaphic microarthropods were also caught. EDAPHOLOG is a novel device that consumes little power, rugged enough to operate in the field for extended periods of time, and can be remotely controlled. It detects surface- and soil-dwelling microarthropods real-time, and with high accuracy, however, it is less accurate to estimate body size. The system is especially suitable in field research focusing on temporal activity of microarthropods. Because it is non-invasive, studies requiring long term monitoring, such as soil remediation or ecosystem restoration projects, will also find EDAPHOLOG useful. This article is protected by copyright. All rights reserved.