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

Abstract

Ecosystem engineers create habitat that can be used by other species in multiple ways, such as refugees from predators, places to breed, or areas with increased prey resources. I conducted a series of enclosure experiments to: (1) determine if salamanders use earthworm burrows, and (2) examine the potential influence of earthworm burrow use and indirect effects on salamander intra- and interspecific competition, predator avoidance, and seasonal performance. I found that one species of woodland salamander, Plethodon cinereus, used earthworm burrows 50% of the time when burrows were present. Neither adults nor juveniles of the congeneric P. glutinosus used earthworm burrows. Intraspecific, but not interspecific, competition by P. cinereus affected salamander behavior when earthworms were absent, with P. cinereus found under cover objects >70% of the time when alone or with a P. glutinosus, but only 40% of the time when with another P. cinereus. When earthworms were present, the behavior of P. cinereus was similar across salamander treatments. Earthworms decreased the amount of leaf litter and microinvertebrates, although this did not affect salamander mass. In subsequent experiments using only P. cinereus, the refuge provided by earthworm burrows increased the survival of P. cinereus over the winter and allowed P. cinereus to avoid being consumed by the common garter snake (Thamnophis sirtalis). Because earthworm burrows provide a refuge for P. cinereus during intraspecific encounters, in the presence of a predator and over the winter, they may serve as an important belowground-aboveground linkage in eastern forests where salamanders are common.

Effects of Red-Backed Salamanders on Ecosystem Functions

“…The presence of earthworms can further complicate the relationship of salamanders and litter decomposition. Adult nightcrawlers ( Lumbricus terrestris ) burrows provide refuge for red-backed salamanders from extreme temperatures and predators, but reduce leaf litter and microarthropod abundance [56]. Juvenile nightcrawlers can be an important prey source for salamanders [56].…”

“…Adult nightcrawlers ( Lumbricus terrestris ) burrows provide refuge for red-backed salamanders from extreme temperatures and predators, but reduce leaf litter and microarthropod abundance [56]. Juvenile nightcrawlers can be an important prey source for salamanders [56]. In small enclosures, the consumption of juvenile earthworms by adult salamanders reduced the rate of litter decomposition, but the presence of adult earthworms overwhelmed any effect of salamanders by breaking down nearly all leave litter [57].…”

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

“…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. Also, there is evidence that salamander behavioural responses to invasive earthworms can be learned within a single generation.…”

Unexpected earthworm effects on forest understory plants

“…For example, seeds may be affected by direct consumption, while seedlings may be affected by desiccation of fine roots after leaf litter disappearance [9]. In addition, earthworm relative abundance and their associated impacts are also affected by land use history and grazing regimes [17], facilitation between earthworms and non-native plant species [7], and alterations of predator–prey interactions [6,18]. Furthermore, earthworms and abundant white-tailed deer ( Odocoileus virginiana Zimmermann) in North America may interact and affect plants in multiple yet poorly understood ways.…”