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

Abstract

The influence of three aromatic plant species, laurel (Laurus nobilisL.), myrtle (Myrtus communisL.), and French lavender (Lavandula stoechasL.), 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 constitutingL. nobilisessential oil were 1,8-cineole (48.1%), eugenol (12.3%), and α-pinene (6.0%);M. communisoil consisted of α-pinene (31.2%), myrtenyl acetate (19.3%), and 1,8-cineole (16.1%); andL. stoechasconsisted of fenchone (46.7%), camphor (9.9%), and 1,8-cineole (9.0%).L. nobilispresented the highest inhibition against bacterial colonies (44.9%) and lowered soil respiration and microbial biomass when compared to control soils. In contrast,M. comunnisandL. stoechaswere 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.