Abstract
The introduction of invasive earthworms initiates physical and chemical alterations in previously earthworm-free forest soils, which triggers an ecological cascade. The most apparent step is the shift in the herbaceous plant community composition. However, some species, such as Arisaema triphyllum (jack-in-the-pulpit), persist where earthworms are present. It has been hypothesized that A. triphyllum produces insoluble oxalate, an herbivory deterrent, in the presence of earthworms. This study aimed to distinguish between the effects of earthworm-induced changes in soils and the physical presence of earthworms on oxalate production. As such, a two-way factorial greenhouse trial was conducted using uninvaded soils to test this hypothesis for two invasive earthworm species (Amynthas agrestis and Lumbricus rubellus). The sequential extraction of oxalates in A. triphyllum corms was performed with absolute ethanol, deionized water, acetic acid and HCl, representing fractions of decreasing solubility. Earthworm presence increased water-soluble (p = 0.002) and total oxalate (p = 0.022) significantly, but only marginally significantly for HCl-soluble oxalate (p = 0.065). The corms of plants grown in soils previously exposed to the two species did not differ in oxalate production when earthworms were not present. However, the data suggest that earthworms affect corm oxalate concentrations and that the sequence of invasion matters for oxalate production by A. triphyllum.
Highlights
IntroductionThe introduction of invasive earthworms initiates physical and chemical alterations in previously earthworm-free forest soils, which triggers an ecological cascade
Soil Science and Ecology Department, Faculty of Forestry, Istanbul University-Cerrahpaşa, Department of Plant and Soil Science, University of Vermont, Burlington, VT 05405, USA
The effect tests showed that there was no significant difference in water-soluble oxalate among the soil earthworms pretreatments (SOIL) treatments
Summary
The introduction of invasive earthworms initiates physical and chemical alterations in previously earthworm-free forest soils, which triggers an ecological cascade. The most apparent step is the shift in the herbaceous plant community composition. Some species, such as Arisaema triphyllum (jack-in-the-pulpit), persist where earthworms are present. The corms of plants grown in soils previously exposed to the two species did not differ in oxalate production when earthworms were not present. 1. Introduction with regard to jurisdictional claims in Earthworm invasions into previously uninvaded forests cause severe disturbances in forested ecosystems where the soils and plant community structure have developed in the absence of these invertebrates [1,2,3,4]. The invasion of woodlands by earthworms results in the loss of organic soil horizons
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