STABILIZATION OF MOTORWAY SLOPES WITH HERBACEOUS COVER, CATALONIA, SPAIN

We monitored several herbaceous species for revegetating motorway slop es in Catalonia, Spain, a Mediterranean country. Two main kinds of tre atments were applied: hydroseeding on bare marl, chalk, and slates, an d hydroseeding on embankments over gentler slopes, where soil material s previously removed were spread before hydroseeding. The greatest her baceous cover was obtained by hydroseeding after soil replacement, and marl was the most suitable bare substratum for hydroseeding. Physical characteristics such as schistosity plane in slates and softness or s urface irregularity in chalk determined the outcome of revegetation ef forts. The most immediate stabilization of soils was obtained on south ern exposures with autumnal applications. Grasses, markedly of the gen era Lolium and Festuca, were dominant in the herbaceous cover at the e nd of the monitoring period. Natural invasive vegetation was composed of ruderal species, but no representatives of the adjacent forest or m aquis community were found.