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, which cause significant economic,
ecological, and social impacts. Natural forest succession is usually
slow on landslide scars due to poor soil structure and the lack of seeds
of woody plant seeds, and often comes with a higher risk of repeated
landslide. Ecological forest restoration has recently been suggested as
an effective alternative to restore the exposed landslide scars,
however, a comprehensive study to identify effective landslide
restoration strategies remains lacking, particularly associated with
seed treatment methods and species selection. Here we evaluated the
effectiveness of different seed coating treatments of both pioneer and
later successional tree species of different seed sizes on seed
germination in a one-year study on three landslides in Hong Kong. Our
results show that bare seeds had germination rates of 17 to 67% across
all selected species (n=7). Biochar-dominant seed coating formulation
boosted an additional 9.33 (SE= 0.04) in seed germination rate, while
the clay-dominant seed coating formulation did not show significant
effect on germination. Our results also show that medium and
large-seeded non-pioneer species have significantly higher germination
rates than pioneer species. These results collectively suggest that
direct seeding using a biochar seed coat is a manageable and useful
method to enhance tree seed germination—an essential first step to
restore the forests after landslide disturbances in Hong Kong, with
potential to be extended to other humid tropical and subtropical
forests.