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

Abstract

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 are 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 data base; 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. Secondly, we compared the number of individuals collected by EDAPHOLOG traps, pitfall traps and soil extraction method in an alfalfa field. Thirdly, we deployed a total of 100 EDAPHOLOG probes in nine different habitats for over 3 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) was 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 3‐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.

An Opto-Electronic Sensor-Ring to Detect Arthropods of Significantly Different Body Sizes

“…The detectability of soil-dwelling and surface-living invertebrates varies with different body shapes, sizes, and appendages (e.g., hairs, scales), which was already observed in our previous study [35].…”

“…However, the accuracy of detection depends on the size, shape, and even on the movement pattern of the given specimen [11]. In our previous work [35,36], we found that the morphology of arthropods (pigmentation, color, hairs, and appendages) influenced the detectability. These differences in detectability could be seen in the current experiments as well.…”

“…The earlier version of our infrared sensor [35,36] was built for soil microarthropods with small body sizes and reached a 90%-95% detection rate only at 1 mm body size. In contrast, the new IRSR-2 sensor-ring detected smaller (>0.6 mm) individuals with high accuracy.…”

“…We aimed to build a real-time monitoring instrument for pest management and environmental protection that could fulfill both the requirements of farming needs and larger-scale environmental policies. Our previous prototype, called EDAPHOLOG, is a monitoring device that operates with opto-electronic sensors and can detect the activity of animals living in the soil [35]. We have previously developed another type of infrared sensor for soil microarthropods that was also used in EDAPHOLOG probes [36].…”

Detecting Soil Microarthropods with a Camera-Supported Trap

“…Previously, the so-called EDAPHOLOG probe was developed to reduce energy consumption and human effort and to gain more information about the activity of soil-dwelling microarthropods [20]. In this probe, an infrared (IR) sensor was optimized for detecting soil-living microarthropods [21].…”