**7. Ecological hazard**

Ecological invasion of neophyte plant and animal taxa has now become one of the most feared sources of natural habitat degradation according to many nationwide and international surveys (e.g. Molnár et al., 2008) The most frequent method of neophyte introduction is their agricultural use through which their large-scale distribution and successful establishment are intensively supported by human activities. Suggesting new plant taxa to be involved in agricultural production bears the hazard of suggesting a new potential invasive plant too. Hence thorough investigation and consideration must be taken before introducing any new agricultural crop, especially a new biomass plant.

*Elymus elongatus* is a rare, native plant species to Hungary; consequently its Szarvasi-1 cultivar is much more favourable for agricultural production in Hungary than other exotic biomass grasses. Szarvasi-1 carries genetic material that is derived from only indigenous populations of *E. elongatus* in Hungary. Hence the cultivar can be regarded as an indigenous taxon, so its potential as an ecological hazard in terms of invasivity is low. Since Szarvasi-1 energy grass has a transient seedbank type (i.e. its seeds lose their viability in a year), its cropfields can be transformed into any other crop without the problem of resprouting.

High competitive ability as well as fast growth dynamics are the main characters of Szarvasi-1 energy grass when it manages to establish itself completely. As our experiments suggested, weed species can outcompete Szarvasi-1 energy grass individuals if there is only incomplete sprouting and the development of tillers are slow. In this case, the stands of Szarvasi-1 energy grass crop remain open, and weeds can gain a significant advantage in growing and spreading. This is why we expect Szarvasi-1 energy grass not to be able to invade intact natural or semi-natural habitats, not even in the close vicinity of energy grass fields from where the seeds can escape in large quantities. Energy grass can germinate only in anthropogenic habitats where continuous and intensive disturbance takes place (e.g. field margins, dirt roads and banks following man-made canals). Since energy grass cannot spread vegetatively (i.e. with rhizomes), it will not become such a hazardous invasive species as for instance *Solidago gigantea* or *Reynoutria japonica*, at least not in its native habitat, in Eastern Europe.

For the rest of the world, it is worth being cautious. From Australia and the US the aggressive spread of energy grass has been reported (e.g. Cox, 2001; Walsh, 2008), where the plant formed homogeneous, closed stands outcompeting all the native elements of the local vegetation. Although this happened only in very close environments to the lands recultivated by *Elymus elongatus* (e.g. steep slopes and bank of canals), this might indicate the possibilities of its invasive spreading, particularly in those countries where natural specialist herbivores, as well as pathogenic agents of *Elymus elongatus* are missing.
