Evaluation of Shrubs to Slope Consolidation in Urban Landscape

Shrubs are often used to consolidate slopes in the urban landscape. Only few species are commonly used in the city environment bestowing on the city a monotonous appearance. The aim of this trial, set up at Minoprio Foundation (Vertemate con Minoprio, Como, Italy; 45 degrees 44' N, 9 degrees 04' E), was to collect data about the performance of 25 shrub species or cultivars grown in a slope during two seasons. Moreover, in order to evaluate weeds influence on plant growth and the weeding time, two mulches (a biodegradable textile and a polypropylene sheet) were used in comparison with control (no mulch). The experimental design was a randomized block design with 3 replicates. Each block was constituted by 75 experimental plots (25 per mulching treatment) of 8 m(2) area. Shrubs were planted in late spring of 2007. In order to simulate urban conditions no pruning and disease control were applied. Irrigation was carried out only in the first growing season. Plant height and covering area percentage were measured every 2 months. Plant phenology and health state were recorded weekly. Weeds were removed twice in the first year and three times in second year. Time for weed removal was recorded for each experimental plot. Results show that the highest growth was detected in mulched plots probably due to both limited weed competition for water and nutrients and lower water loss by evaporation. Among shrubs differences in growth and ground covering were observed.