Gravel bars: a key habitat of gravel-bed rivers for vegetation

摘要

This papers examines the importance of gravel bars in terms of a substrate forrecruitment, colonisation and development of ground flora and woody vegetation viatwo European case studies. Experimental work on the River Tagliamento in Italy isused to explore the role of substrate particle size and elevation on recruitment andgrowth of seedlings and cuttings (Populus nigra L. and Salix elaeagnos Scop.).Meanwhile on the River Tummel in Scotland, the pattern of vegetation communitiesare related to bar morphology and sedimentology via field survey. Both studies revealthe critical importance of bar morphology and substrate particle size, via their con-trol on inundation frequency, substrate stability and moisture availability, in terms ofvegetation development on gravel bars from the initial colonisation stage to veg-etation communities present after more than decade.