The influence of habitat provisioning: use of earthworm burrows by the terrestrial salamander, Plethodon cinereus

Abstract

Studies examining the influence of habitat provisioning by one species on the behavior of other species can provide key insights regarding impacts of ecosystem engineers on the availability of resources to other species. More specifically, an organism's use of additional habitat provided by ecosystem engineers may affect the interpretation of observational or demographic data. We chose to examine the possible influence of earthworms, as ecosystem engineers, on the behavior of terrestrial salamanders, common forest vertebrates in North America. We conducted two experiments in microcosms to examine whether the earthworm Lumbricus terrestris acted as an ecosystem engineer by providing additional habitat (burrows) for Plethodon cinereus, a common woodland salamander. We also examined whether the behavioral changes of the nonburrowing, fossorial P. cinereus differed across age classes. Adults and juveniles responded similarly, with both adults and juveniles found under cover objects more often when earthworms were absent and using earthworm burrows when available. Our field data supported our experimental data in that greater numbers of earthworms on field plots were associated with a lower proportion of cover objects being occupied by salamanders (i.e., salamanders were likely underground). We found no differences in the response of adults and juveniles to the presence of earthworms. By providing underground habitat for a common terrestrial amphibian, the presence of earthworms may impact demographic studies on salamanders and conclusions drawn from those studies regarding aboveground faunal communities in eastern North America.

Invasive Asian earthworms of the genus Amynthas alter microhabitat use by terrestrial salamanders

“…Cáceres-Charneco and Ransom (2010) proposed that reductions in salamander surface densities could indicate increased underground activity due to the use of burrows created by L. terrestris. Therefore, a decrease in surface density may not represent a true decline in salamander population abundance, but rather a reduction in surface activity due to the loss of suitable surface habitat and the presence of invasive anecic earthworm burrows.…”

“…Literature regarding the effects of invasive earthworms on salamanders is scarce, but recent investigations into the behavioural interactions between invasive earthworms and the Eastern Red-backed Salamander (Plethodon cinereus (Green, 1818)) have focused on the role of the deep-burrowing, European nightcrawler (Lumbricus terrestris L., 1758) as an ecosystem engineer (Cáceres-Charneco and Ransom 2010;Ransom 2011Ransom , 2012aRansom , 2012b. Ransom (2011Ransom ( , 2012b showed that salamander fossorial activity is influenced by the presence of earthworm burrows and demonstrated potential benefits of invasive earthworm burrows for salamanders, including bolstering overwintering success and serving as refugia from predators.…”

Side‐swiped: ecological cascades emanating from earthworm invasions

“…Invasive earthworms also indirectly affect wildlife by altering habitat structure. Their extensive networks of burrows may benefit some wildlife (Cáceres‐Charneco and Ransom ), but by eliminating leaf litter layers, earthworms may exacerbate soil warming or drying that could negatively affect moisture‐ or temperature‐sensitive taxa (Reich et al . ).…”

Earthworms, as ecosystem engineers, influence multiple aspects of a salamander’s ecology

“…Although earthworms can be salamander prey (Maerz et al 2005), if this trophic interaction is the dominant interaction between earthworms and salamanders, one might expect diurnal salamander counts to be positively correlated with earthworm numbers. However, field surveys in Virginia and in New York have indicated that earthworm numbers are negatively correlated with diurnal, above-ground salamander counts (Maerz et al 2009;Cáceres-Charneco and Ransom 2010).…”