Microenvironment created by L. may affect cover and diversity of coexisting species in urban vegetation.

Some plant species may exhibit new microenvironments which lead to significant changes in the cover and diversity of the coexisting species. In this investigation, we evaluated the effects of L. on the cover and diversity of the associated plant species in the urban vegetation. A total of 70 plots were conducted in sites with- and without this species in urban gardens. Cover of the associated species and different diversity indices including species richness, Shannon-Wiener, evenness, and Simpson indices were measured. The allelopathic potential of . was verified using its rhizosphere and non-rhizosphere soils on two target species existing within the same environment. Some soil criteria and seed sizes of the associated species were also determined. Most of the coexisting weeds were reduced in terms of their cover in plots with . The reduction of plant diversity depended on its cover. Besides, the aboveground biomass was reduced in sites comprising . The degree of inhibition was not related to the seed size of the species found. This species reduced the incident solar radiation and the local temperature over the soil surface. The locations exhibiting such species contained lower contents of available potassium and zinc. Rhizosphere soil of . substantially inhibited germination and growth of , but it didn't do so for . Reduction in cover, diversity, and biomass of the urban weeds associated with . may be related to the reduction of received solar radiation, soil temperature, and nutrient availability. The allelopathic potential of . may have a partial role in this reduction. These results suggest that . may create a microenvironment of new conditions not favorable for most of the coexisting species.