Spatial and Temporal Dynamics of Exotic Earthworm Communities Along Invasion Fronts in a Temperate Hardwood Forest in South-Central New York (USA)

Abstract

The invasion of North American forests by exotic earthworms is producing profound ecosystem changes, such as alterations in soil nutrient cycling, and redistribution and loss of soil organic matter. However, the present and future extent of these invasions is difficult to evaluate without a better understanding of the factors that control the distribution and abundance of earthworms in previously non-invaded habitats. In this study, the species composition and short-term dynamics of three exotic earthworm invasion fronts were studied at a northern hardwood forest in south-central New York State (USA). Belt transects were established at each of the three locations to sample from earthworm-invaded areas through transition zones and into invasion front areas. Lumbricus rubellus, L. terrestris and Octolasion tyrtaeum were the most common species, but their distribution was not homogeneous along the transects. Whereas, L. rubellus was the only species with relatively high adult densities at transition zones and invasion fronts, L. terrestris and O. tyrtaeum occurred mostly in the heavily earthworminvaded areas and were rare at the invasion fronts. The density of earthworms along the transects decreased by 60-

Distribution and impacts of invasive earthworms in Canadian forest ecosystems

“…They found that, except for L. terrestris, distances to human development were poor predictors of earthworm biomass and assemblages. A similar study in south-central New York (Suárez et al 2006) reported that while forest type, and distance to agricultural clearings and wet refugia were significant predictors of earthworm presence, the distance to streams and roads were not. Thus it appears that anthropochorous dispersal is only one of the many factors that influence invasion patterns and dynamics.…”

“…Earthworm invasions typically occur in waves (Hendrix and Bohlen 2002;James and Hendrix 2004;Suárez et al 2006;Eisenhauer et al 2007). Epigeic species are usually the first to arrive because they are small, easily transported and are able to utilize the undisturbed forest floor (Dymond et al 1997).…”

Forest floor decomposition, metal exchangeability, and metal bioaccumulation by exotic earthworms: Amynthas agrestis and Lumbricus rubellus

“…L. rubellus were added to at 0.7 ± 0.1 g dw (∼10 g m −2 ) per forest floor pot at about 0.4 ± 0.1 g dw per individual or two earthworms per pot. This matches approximately 25 individuals m −2 , at the high end of natural occurrence in northern hardwood forests (Suárez et al 2006). Forest floor pots were maintained at 40-60 % WHC throughout the experiment with deionized water.…”

Land use history determines non-native earthworm impacts on atmospheric methane consumption in forest soils, central New York State

“…Across the study area, areas heavily invaded by earthworms are separated from non-invaded areas by transitions zones with intermediate levels of earthworm abundance and activity (Sua´rez et al 2006). Earthwormfree areas exhibit a forest floor layer (Oe, Oa layers) averaging 4 cm in thickness over the mineral soil that has a mean carbon content of 5600 g C m (2 in the upper 12 cm.…”

“…I avoided sampling on the day after significant rainfall that would have saturated soil pores with water. Earthworms are still active at this time of the year (Sua´rez et al 2006), provided the soils stay moist, i.e., earthworm activity slows in response to dry soil in the mild climate of central New York State.…”