Vegetation regeneration on natural terrain landslides in Hong Kong: direct seeding of native species as a restoration tool

Abstract

Landslides are common in tropical and subtropical regions with hilly terrains and heavy rainstorms, and can cause significant economic, ecological, and social impacts. Natural forest succession is usually slow on landslides due to poor soil structure and lack of woody plant seeds, and often comes with a higher risk of repeated landslides. Active forest restoration has been increasingly suggested as an effective alternative to restore exposed landslide scars. Here, we evaluated the effectiveness of using dif- ferent seed coatings and surface soil treatments on seed germination and seedling establishment of pioneer and late-successional tree species on landslide scars in Hong Kong. Our results show that biochar-dominant seed coating boosted seed ger- mination rate by an additional 9.33% (Standard error = 0.04), while clay-dominant seed coating did not show significant effects. The effects on seedling survival were not significant in both seed coating and surface soil treatments. Our results also show that large seed and later successional species have significantly higher germination rates than pioneer species and are able to successfully establish on landslide sites. These results suggest that direct seeding using a biochar seed coat with large seeds or late-successional species is a useful method to enhance tree seed germination—an essential first step to restore the forests after landslide disturbances, with potential to be extended to other humid tropical and subtropical forests.