The Influence of Aromatic Plants on Microbial Biomass and Respiration in a Natural Ecosystem

Abstract

The influence of three aromatic plant species, laurel ( Laurus nobilis L.), myrtle ( Myrtus communis L.), and French lavender ( Lavandula stoechas L.), on top soil microbial biomass, respiration rates, and bacterial colonies was investigated. Fresh, mature plant material was introduced into a typical Mediterranean habitat in Northern Greece. The essential oil chemical compositions from the aromatics used in the study were evaluated by GC-MS analysis. The major compounds constituting L. nobilis essential oil were 1,8-cineole (48.1%), eugenol (12.3%), and α-pinene (6.0%); M. communis oil consisted of α-pinene (31.2%), myrtenyl acetate (19.3%), and 1,8-cineole (16.1%); and L. stoechas consisted of fenchone (46.7%), camphor (9.9%), and 1,8-cineole (9.0%). L. nobilis presented the highest inhibition against bacterial colonies (44.9%) and lowered soil respiration and microbial biomass when compared to control soils. In contrast, M. comunnis and L. stoechas were found to augment bacterial activity by 85.9% and 63.8%, respectively, and to increase soil respiration (1.5-fold) and microbial biomass (2.5-fold) compared to control soil samples. These two plants are proposed for further investigations in biodegradation programs.