Effects of an Ecosystem Engineer on Belowground Movement of Microarthropods

Abstract

Ecosystem engineers affect other species by changing physical environments. Such changes may influence movement of organisms, particularly belowground where soil permeability can restrict dispersal. We investigated whether earthworms, iconic ecosystem engineers, influence microarthropod movement. Our experiment tested whether movement is affected by tunnels (i.e., burrows), earthworm excreta (mucus, castings), or earthworms themselves. Earthworm burrows form tunnel networks that may facilitate movement. This effect may be enhanced by excreta, which could provide resources for microarthropods moving along the network. Earthworms may also promote movement via phoresy. Conversely, negative effects could occur if earthworms alter predator-prey relationships or change competitive interactions between microarthropods. We used microcosms consisting of a box connecting a “source” container in which microarthropods were present and a “destination” container filled with autoclaved soil. Treatments were set up within the boxes, which also contained autoclaved soil, as follows: 1) control with no burrows; 2) artificial burrows with no excreta; 3) abandoned burrows with excreta but no earthworms; and 4) earthworms (Lumbricus rubellus) present in burrows. Half of the replicates were sampled once after eight days, while the other half were sampled repeatedly to examine movement over time. Rather than performing classical pairwise comparisons to test our hypotheses, we used AICc to assess support for three competing models (presence of tunnels, excreta, and earthworms). More individuals of Collembola, Mesostigmata, and all microarthropods together dispersed when tunnels were present. Models that included excreta and earthworms were less well supported. Total numbers of dispersing Oribatida and Prostigmata+Astigmata were not well explained by any models tested. Further research is needed to examine the impact of soil structure and ecosystem engineering on movement belowground, as the substantial increase in movement of some microarthropods when corridors were present suggests these factors can strongly affect colonization and community assembly.

Effects of temperature and soil fauna on the reduction and leaching of deoxynivalenol and zearalenone from Fusarium graminearum-infected maize stubbles

“…Results from arable soil (Luvisol like in the present study) demonstrated an increase in collembolan numbers (hemiedaphic species Folsomia candida) in the presence of the endogeic earthworm species Aporrectodea caliginosa due to a habitat improvement by the earthworm burrow network (Wickenbrock and Heisler 1997). A laboratory study on the epi-endogeic earthworm species Lumbricus rubellus revealed positive effects on collembolans in forest soil through developing a pore network and providing bioavailable secretions therein (Cameron et al 2013). The results from a study with earthworms and collembolans in forest soil mesocosms containing beech saplings suggest that soil fauna interactions mainly vary with the identity of species and community composition rather than with similarity of traits like body size or microhabitat association (Grubert et al 2016).…”

Invasive earthworms erode soil biodiversity: A meta‐analysis

“…In turn, decomposition rates increase rapidly together with changes in soil structure with a notable decline of organic layers (Ashton, Hyatt, Howe, Gurevitch, & Lerdau, ). These earthworm effects are further manifested via changes in the soil chemical environment (Eisenhauer, Partsch, Parkinson, & Scheu, ), spatial distribution of soil micro‐organisms (McLean, Migge‐Kleian, & Parkinson, ), soil fauna movements (Cameron, Proctor, & Bayne, ) and plant community composition (Craven et al., ; Dobson & Blossey, ).…”

Interactions of Soil Species Exposed to CuO NMs are Different From Cu Salt: A Multispecies Test

“…However, in nature species are virtually never alone and it is well-known that species interact, for example, via predation, competition, or mutualism. This interaction generates synergistic or antagonystic effects for the community structure and function, which carries key importance for the ecosystem sustainability as a whole. − Such interactions also affect the hazard and, hence, risk assessment. Although multispecies testing can be more laborious and require more resources than a single species test, it contains key information when it comes to deriving regulatory PNEC (predicted no effect concentration) due to their close resemblance to nature.…”