this research was carried out to investigate allelopathic effect of peganum harmala on seed germination of bromus tectorum. aboveground and underground tissues of peganum harmala in addition to its seeds were collected from bijar rangelands. collected materials of root, leaves, stem, seeds and a complex of mentioned parts were dried and powder. the research was performed at the greenhouse condi...

Ecosystem susceptibility to invasion by nonnative species is poorly understood, but evidence is increasing that spatial and temporal variability in resources has large-scale effects. We conducted a study in Artemisia tridentata ecosystems at two Great Basin locations examining differences in resource availability and invasibility of Bromus tectorum over elevation gradients and in response to di...