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Disturbance is an important determinant on successful invasion of P. corethrurus in tropics

Pontoscolex corethrurus, a widespread, peregrine earthworm species, is one of the most ubiquitous exotic species and the dominant species in tropical croplands and plantations. However, the mechanisms by which the exotic earthworms invade new habitats are largely unknown.

In a study published in Biological Invasions, researchers from Xishuangbanna Tropical Botanical Garden (XTBG) compared the effects of three factors (propagule pressure, habitat disturbance, and litter resource on the invasion of earthworms into large areas of tropical natural forests undergoing conversion into plantations and farmlands.

The researchers designed two independents but complementary mesocosm experiments: a moderate disturbance experiment and a severe disturbance experiment, in a natural forest.

In the moderate disturbance experiment, they manipulated habitat disturbance (no disturbance vs moderate disturbance) and propagule pressure as independent factors. In the severe disturbance experiment, they manipulated propagule pressure, litter quality (LQ) and leaf species/litter diversity (LD) as independent factors that affect the establishment of P. corethrurus in a simulated severely disturbed system.

They found that disturbance (severe vs no or moderate disturbance) overwhelmed the effects of propagule pressure and litter resource on the establishment of P. corethrurus. The alteration in leaf LQ and LD were not important determinants in the successful invasion by or dominance of P. corethrurus in tropical natural forests undergoing conversion into rubber plantations.

"Our results highlight the importance of protecting tropical natural forests from severe anthropogenic disturbances," said Prof. Yang Xiaodong, principal Investigator of the study.