South East New Territories (SENT) Landfill Landscape Restoration: One-off Interim Monitoring Exercise

The project is a horticultural research study, comprising analysis and review of the success of plant establishment (with particular regard to native woodland species) at the ongoing landscape restoration at the South East New Territories (SENT) Landfill in Hong Kong.

The restoration masterplan for the landfill envisages a network of native woodland, scrub and grassland that can be used for rural recreation, with links to the adjacent Government designated Country Park.

The landfill restoration began in 1994 and to date, 12 of 20 proposed phases of restoration have been completed. It is a demanding site for landscape works due to its location, climatic factors and landfill engineering requirements. The focus of the research was on the performance of native plant species which have been used in the restoration to enhance biodiversity, habitat creation and to further the Hong Kong Government's sustainability goals.

Native plants are recognised locally as being difficult to establish on Hong Kong's exposed uplands and coastal sites, with their poor soils. As a further issue, over the 24 years of the restoration, the environmental background at the landfill has changed. These changes have included climate change (typhoons of increased severity, warmer winters and hotter summers); the recent surge in the population of wild boar (Sus scrofa) and the arrival in Hong Kong of Red Imported Fire Ants (Solenopsis invicta), all of which have posed problems not foreseen at the outset of the restoration. The team was interested to know which species had adapted best to these changes.

The focus of the research exercise was not academic but instead, the methodology aimed to derive practical results that could be meaningfully used by future landscape designers and managers.

The research work was carried out by URBIS Limited's teams of horticulturists over the course of more than a year and employed a rigorous methodology that was intended to be as objective and scientifically valid as circumstances allowed. The work included detailed site measurements, taken over the course of many weeks, of growth, morbidity and mortality of every species used over the course of the restoration to date.

This data was then analysed to produce a wealth of information on the performance of individual species and their effectiveness in achieving landscape restoration objectives. In addition, by using standard deviation analysis to compare original planting plans to those species found on site, an index of those (native) species best adapted to the site conditions was produced (a ' Recommended Plant Index' or RPI).

Climatic, biotic and abiotic external influences on plant establishment were also analysed, resulting in recommendations for amendments to planting techniques and management actions for future phases of restoration.

This rigorously executed and, fully quantified and documented piece of horticultural research is believed to be the first comprehensively quantified and statistically verified research of this type and on this scale in Hong Kong. Its potential benefits (particularly the RPI of native plants) to future phases of this restoration and also to similar future projects in Hong Kong is believed to be very significant.