Exotic plantations differ in "nursing" an understory invader: A probe into invasional meltdown.

Forest plantations most likely promote exotic plant invasion. Using an in situ monitoring method, this study investigated the traits correlated with growth and reproduction of an understory invader, L., and ecological factors including understory irradiance, soil stoichiometry and microbial patterns associated with these traits in different exotic plantations of L. and Parl. at Mount Lao, Qingdao, China. We found that the traits of underneath the stand might be situated at the fast side of the trait economic spectrum. The stand appeared to "nurse" . Furthermore, we intended to explain the nurse effects of stands by examining their ecological factors. First, the stand created understory light attenuation, which matched the sciophilous feature of . Second, the soil beneath the stand might benefit more since the soil has greater resource availability. Third, a higher microbial diversity was found in the soil derived from underneath the stand. A greater abundance of plant pathogens was detected in the soil derived from in the stand, while more abundant mycorrhizal fungi were detected in the stand. We speculate that plant pathogens can defend from aggression from other understory competitors. The mycorrhizal fungi in the stand might benefit while simultaneously benefiting other understory plants. Intensive competition from other plants might interfere with . The potential relationships between plant performance and ecological factors may explain the invasion mechanism of The present study provides a novel insight on the facilitative effects of exotic tree plantation on an exotic herb through the modification of soil biota, with implications for the biocontrol of invasive species and forest management and conservation.