LCSD saddened by collapse of banyan tree branches at Kowloon Park
The Leisure and Cultural Services Department (LCSD) was saddened by the collapse of one third of the branches of a Chinese banyan tree at Kowloon Park.
Although Chinese banyan tree is common in Hong Kong, this one in Kowloon Park is listed on the Register of Old and Valuable Trees as it is aged over 100 years.
The LCSD has been very concerned about its health condition. From late 2004 to early 2005, the department found its leaves falling quite often.
Its root system might have been affected during the redevelopment of Kowloon Park in 1989. After the redevelopment, the paving of concrete slabs on the peripheral area of the tree base and park-goers' stepping on the soil resulted in soil compaction, hindering air and water infiltration into the soil layers. This also affected the respiration and development of the root system, and led to the infection of the tree by fungi.
Over the past two years, the LCSD has consulted local academics and experts, as well as tree experts from the Guangdong Forestry Bureau of China and the International Society of Arboriculture in the US on possible measures to save the banyan tree. Remedial measures taken include:
- Turning over the soil on which the banyan tree grows and replacing the top soil with better quality soil to improve its permeability
- Inserting porous plastic tubes into the peripheral area of the tree to facilitate the spreading of fertilisers to deep soil layers.
- Using bamboo poles to expedite the growth of aerial roots to the soil surface and their development into supporting roots.
- Utilising the diagnostic tool PICUS Sonic Tomograph to assess the internal condition of the tree.
- Sending leave and soil samples to a botanic laboratory in the US for analysis. The results revealed relatively high levels of ammonium and alkalinity in the soil. Calcium compounds have been injected into the soil to lower the pH value.
- Vertical mulchings were bored in the peripheral area of the roots and filled with good quality substrates so as to induce root development.
- Following the advice of tree experts, fungicide Tridemorph was used to annihilate fungal diseases in the root system.
The health condition of the banyan tree has improved after a series of remedial measures in the past two years. Its leaves, roots and aerial roots were seen growing. However, its root system has not shown much improvement and with the passage of a tropical cyclone and heavy rains, part of its branches collapsed.
The department will strive to save the tree. The staff will remove the withered limbs of the tree to reduce its weight. The Architectural Services Department was contacted to help stabilise the tree with wires. The LCSD will keep liaising with local and overseas experts for further remedial measures.
Ends/Monday, August 13, 2007