Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract Full Text

Effects of Chenopodium ambrosioides on soil enzyme activity, microorganism quantity and soil nutrient content of three cultivated pastures of rhizosphere soil in northwestern Sichuan.

Abstract

The global warming and human activities are major drivers that plant invasions are increasing in mountain systems. Chenopodium ambrosioides L., one of the aromatic herbaceous species of the Chenopodium genus, native to tropical America, has become major invasive plant in China, and will gradually spread to high-elevation environments of Northwestern Sichuan. Previous research indicated that C. ambrosioides gain growth advantage by means of allelopathy. However, the effects of C. ambrosioides on soil microenviroment in alpine meadow are unclear. In order to evaluate the potential ecological risk of invasiveness of C. ambrosioides for an alpine meadow ecosystem of Northwestern Sichuan, the allelopathy of the residue from C. ambrosioides on soil microbes, enzyme activities and soil nutrients of three cultivated pastures, Elymus sibiricus, E. nutans and Poa annua in the rhizosphere soil were studied by pot experiment in alpine meadow of Northwestern Sichuan. The results showed that the residue from C. ambrosioides had effects on soil micro-ecosystem of receptors by (i) With the increase of the residue from C. ambrosioides, the amount of bacteria, fungi and actinomycetes in the rhizosphere soil of E. sibiricus first increased and then decreased. And the amount of bacteria and actinomycetes showed a trend of increase-decrease-increase, but the amount of fungi first increased and then decreased in the rhizosphere soil of E. nutans. The amount of actinomycetes changed significantly in the rhizosphere soil of P. annua. (ii) The activities of soil enzyme including urease, sucrase, cellulose and nitrate reductase in the rhizosphere soil of P. annua, urease and cellulose in the rhizosphere soil of E. sibiricus, and sucrase and nitrate reductase in rhizosphere soil of E. nutans changed significantly. (iii) The residue from C. ambrosioides altered soil nutrients of three pastures. The residue could enhance at the low dose and suppress at the high doses the soil nutrients of E. sibiricus and P. annua, and could increase available nutrient at the high doses and decreased soil total nutrient at the low doses in rhizosphere soil of E. nutans. All these suggested that C. ambrosioides could modify the composition of soil biota, the activities of soil enzyme and soil nutrition, and invasiveness of C. ambrosioides maybe alter competition situation of plant in alpine meadow by the allelopathy on soil micro-ecosystem.