| Revegetation of soil slopes has become feasible to enhance both the visual and ecological values of landscapes. Extensive research has been conducted on the growth performance of plant groups such as trees, shrubs or grasses on soil slopes. However, ferns, which are found to colonize the landscapes by transplantation or naturally occurring, are always ignored. They are capable of forming a sustainable and dense green cover and should, therefore, be further investigated. Any common native fern species and their benefits on soil slopes needs to be identified in order to evaluate their value on soil slopes. Other planting methods besides transplantation should also be examined to facilitate fern establishment on soil slopes for revegetation.;An ecological survey on groundcovers of soil slopes in Hong Kong showed that ferns contributed a relatively higher percentage of plant cover than other groundcovers, which showed their strong adaptations to urban landscapes. Common fern species including Blechnum orientale, Cyclosorus parasiticus, Dicranopteris pedata and Pteris vittata were identified. All of them were found on exposed slopes while C. parasiticus and P. vittata also showed tolerance to shaded environment. Urban development led to the significant differences between urban and suburban areas in plant abundance, and the cultivated fern species Nephrolepis auriculata was more commonly found in urban areas.;The benefits of the aforementioned fern species on soil slopes such as their erosion-reducing potential were examined by a rainfall simulation study. Two coverage levels (40% and 80%) of each fern species were tested for erosion control under a heavy rainfall scenario (100 mm h-1). High fern cover reduced both runoff (65.0%) and sediment loss (96.1%) significantly when compared with the control. Other plant traits such as leaf area index, root area ratio and root density were associated with the capability of ferns in erosion mitigation.;The spores of these fern species were examined for their germination and growth potential on the common substrate of soil slopes under various environmental treatments including spore density, soil moisture, fertility and pH. Among them, soil fertility plays a crucial role in promoting spore germination and sporophyte formation. As a result, fern spores mixing with various mulches were grown by a greenhouse and field study. It was found that P. vittata outcompeted other fern species in higher growth rate. This result was consistent with the field trial, in which this fern species had the highest coverage on south-east and south-west facing slopes. The growth of other species such as C. parasiticus was subjected to microclimatic conditions induced by the slope orientation. These results confirmed the feasibility of growing fern from spores on soil slopes and the importance of appropriate species selection in revegetation. |
