Comparison of Pioneer and Native Woodland Species Growing on Top of an Engineered Landfill, Hong Kong: Restoration Programme

Abstract

This study dealt with a restoration project conducted at South‐East New Territories Landfill in Hong Kong, in order to screen suitable tree and shrub species (both native and pioneer species) for revegetation. For engineered landfills, landfill gas migration and leachate contamination to the topsoil are rarely problematic, but the lack of nutrients and moisture and poor physical soil conditions may jeopardize potential woodland establishment. The growth performance of 25 woody plant species subjected to 12 different soil amelioration and seedlings planting methods was compared. The results showed that the general performance (mortality rate, apical height, crown diameter and basal diameter) of pioneer species (notably Acacia species) was much better than that of native species in all blocks of woodland mix and scrub mix. The notch planting method was effective in helping seedling roots to have better contact with soil for water uptake, which subsequently increased the survival rates of seedlings, leading to a better tree coverage. Soil ameliorations (horticultural soil with fertilizer and horse and pig manure) generally increased the seedling survival rate and improved plant growth. Tree coverage on all the plant trial blocks was mainly established by the three Acacia species. A planting distance of 1 m was recommended for woodland establishment, and such dense seedlings planting would achieve a better tree coverage under a shorter period of time (than the distance of 3 m). Difficulties in woodland establishment were discussed, and the strategies for achieving a better tree growth were recommended. Copyright © 2015 John Wiley & Sons, Ltd.

The use of vegetation as a natural strategy for landfill restoration

“…Ecological studies of nonsanitary landfills in Hong Kong have been conducted (Chan, Chu, & Wong, ; Wong, Cheung, & Lan, ; Wong & Yu, ). The authors found that a restored nonsanitary landfill served as a suitable habitat for plants tolerant to LG and leachate (M. H. Wong et al, ). It has been observed that plant communities in landfills are comparable with plant communities in the vicinity after a lengthy period (10 years; El‐Sheikh, Al‐Sodany, Eid, & Shaltout, ) and can have higher densities of plants and animals than the reference sites (3 years; Chen et al, ).…”

Restoration of Plant and Animal Communities in a Sanitary Landfill: A 10‐year Case Study in Hong Kong

“…The selection of pioneer species in the present study was based on our previous research conducted at non‐sanitary landfills (Chan et al , ; Chan et al , ; Wong & Yu, ) and a sanitary landfill (Wong et al , ) in Hong Kong. Some pioneer species, such as A. confusa and L. leucoephala , can adapt to the restored landfill and become self‐seeding at other restored sites.…”

“…This information is important because there is an increasing trend in the number of sanitary landfills, and the plant species chosen for the present sanitary landfill restoration now largely follows those used in previous non-sanitary landfill restoration schemes (Chan et al, 1997;Wong & Yu, 1989a, 1989b. The growth performance of the same pioneer species in sanitary landfills was different from those in non-sanitary landfills, because of the presence of the landfill gas and leachate (Chan et al, 1997;Wong et al, 2015). The present study is a longterm investigation of plants and animals in a restored sanitary landfill over a period of 10 years, with information about plant species selection for future restoration of sanitary landfills provided.…”

Physical, Chemical, and Engineering Properties of Landfill Stabilized Waste

“…In metropolis such as Beijing, on average 1·2 kg MSW was generated per person per day (Dong et al, 2014). Landfill is the most important method for disposal of MSW (Wong et al, 2016) and occupies large amounts of land resource. When the landfills are saturated and thus closed, they can be used for recreation, pasture, or agriculture (Chen et al, 2015).…”

“…When the landfills are saturated and thus closed, they can be used for recreation, pasture, or agriculture (Chen et al, 2015). But the poisonous chemical properties caused by leachate seepage or landfill gas emission, and the poor physical properties caused by compaction or topsoil covering, may hinder the process of landfill restoration (Cassinari et al, 2015;Wong et al, 2016). Even when the old landfills are successfully restored, the enhancement of the land price and the difficulty in site selection (Ahmad et al, 2014) lead to inefficient waste management, and thus, many landfills are overfilled.…”