Effects of earthworms and warming on tree seedling growth: a small-scale microcosm experiment

Abstract

Warming global temperatures are expected to strongly influence plant communities, yet there is limited knowledge of how these changes will interact with stressors such as the invasion of exotic earthworms. We conducted a small-scale microcosm experiment to assess the individual and interactive effects of warming and exotic anecic earthworms (<i>Lumbricus terrestris</i> L.) on the growth of sugar maple seedlings (<i>Acer saccharum</i> Marsh.). After fifty days, the elevated temperature chamber created warmer and drier soil conditions and increased several measures of plant growth, including stem width, stem width : stem height ratio, stem biomass, and fine root biomass. Earthworms did not have any clear impacts on plant growth either on their own or in interactions with the temperature chambers. However, earthworms did reduce surface leaf litter cover and exposed soils, which could exacerbate evaporative losses and moisture stress in field soils resulting from a warming climate under different growing conditions. Future studies should consider long-term earthworm-temperature interactions on sugar maple growth as well as diurnal and seasonal changes in temperature.

Gunnera tinctoria invasions increase, not decrease, earthworm abundance and diversity

“…Although plant invasions could affect all three groups in the long term, the generally higher litter production could provide a shorter-term trophic benefit for epigeic or anecic earthworms. Earthworms may also feed on dead and decaying roots and root exudates, so the supply of this food source might be important too but is much less understood (Curry and Schmidt 2007;Gaudon et al 2020). Modifications in a range of physicochemical soil factors (e.g., water and temperature dynamics, pH, Ca concentrations) associated with plant invasions (Ehrenfeld 2003;2010) could also influence the abundance and biodiversity of soil earthworm populations.…”