MACROPHYTE RICHNESS AND AQUATIC VEGETATION COMPLEXITY OF THE LAKE IDRO (NORTHERN ITALY)

Abstract

A detailed survey was performed to examine the floristic richness and the structural complexity, spatial patterns and conservation value of aquatic plant communities within the littorals of Lake Idro (northern Italy). During the summers of 2010-2011 we proceeded to characterize aquatic macrophyte meadows applying standardized procedures using transects (44) and plots (49) arrayed perpendicular to the shoreline and randomly positioned within the vegetated belt, respectively. Lake Idro is characterized by rather high floristic richness (20 macrophytes) but low levels of vegetation structural complexity (8 vegetation units). Nevertheless, a clear zonation of the littoral vegetation was identified with two main macro-layers: a deeper layer (between 6-10 m of depth) dominated by Chara globularis and an upper one (from 6 m of depth to water-air atmosphere) mainly colonized by alien elodeids (mainly Elodea nuttallii and Lagarosiphon major). For the first time a complete floristic-vegetation analysis of the Lake Idro was presented. Our data confirm the poor ecological status of the basin, even though the lacustrine vegetation can be considered of conservation concern. Further investigations are needed to improve present evaluations, especially with respect to the impact of eutrophication on macrophytic communities.