Re ECF Project: 2006-11

Project Title: Ecological sustainability of vegetated steep soil cutslopes

Applicant: Professor CHU Lee-man of the Chinese University of Hong Kong

Total Approved Grant: $788,600

Duration: 01/07/2008 to 31/8/2012

Project Status/Remarks: Completed

The objectives are:

  1. to study plant performance and growth attributes on steep soil cover cutslopes including soil-nailed cutslopes;
  2. to examine the effects of soil types, weathering extent, slope gradient and water regime on plant growth and root development; and
  3. to select suitable ground cover species for cutslope revegetation in terms of plant coverage, erosion mitigation and rooting characteristics.

Summary of the Findings/Outcomes:
This project studied the ecological status of soil cutslopes and species selection for their revegetation. An ecological survey on species composition and soil characteristics was done on local cutslopes. Of the 80 plant species found, herbs accounted for >60% in number, and vegetation structure was significantly correlated to slope attributes such as soil texture, nutrient composition and soil gradient. For grass species selection, Cenchrus echinatus was the best candidate under water stress and Eremochloa ophiuroides performed the best under fertilization and water stress. In addition, if perennial species are more desirable, Eremochloa ophiuroides, Cynodon dactylon and Paspalum notatum were superior. However, E. ophiuroides gave the greatest root length intensity only at the top 10 cm soil in root boxes, while E. curvula, C. dactylon and P. notatum supported the highest growth with respect to above- and below-ground biomass. The rainfall simulation study using artificial soil panels showed that soil removal was greatly reduced in the presence of grasses, with C. dactylon, P. notatum and E. curvula significantly reduced soil loss, regardless of the culture systems. Besides the conventional species for hydroseeding, E. ophiuroides could be a potential species in terms of its growth performance, root architecture and erosion control.