In response to media enquiries on the removal of two large trees at Bonham Road in front of Tang Chi Ngong Building of the University of Hong Kong (HKU), a Government spokesman today (May 24) made the following statement:
The health and structure of the two Banyan trees on both sides of the slope entrance at Tang Chi Ngong Building in the HKU, Bonham Road, have shown signs of distress. The trunks were leaning towards the footpath along Bonham Road, impacting the structural integrity of the wall, which showed clear signs of deformation, cracking and leaning to the two trees. In view of deteriorating tree conditions, the Government removed the two Banyan trees on May 20.
Since mid-2015, the HKU, members of the Central and Western District Council (C&W DC) and local residents have expressed concern about the safety of the two trees. A professional arborist under the Lands Department’s tree management contract conducts regular inspection and maintenance of the two trees every six months. The maintenance works included pruning to reduce the weight of the tree canopy and removal of fungal infected parts. In spite of this, the health condition of the trees did not improve. In December 2017, after detailed inspections and assessments, the professional arborist concluded that the health and structure of the two trees had continued to deteriorate, including leaning towards the footpath (Tree 1 (T1) and Tree 2 (T2) tilted at 30 and 15 degrees respectively), sparse foliage, relatively low live crown ratios, asymmetric crowns, and tree cavities (about 30 x 30 x 20 cm and about 50 x 30 x 20 cm for T1 and T2 respectively). The results of resistograph for T1 also confirmed decay at the tree cavity.
Moreover, the structure of the wall adjacent to the trees had been impacted by tree growth. The wall leans towards the footpath and road, with deformations and multiple cracks. The walls showed obvious signs of tilting towards Bonham Road, indicating danger of collapse. In a heavy rain event typical of Hong Kong, torrential rain can wash away the soil around the tree roots through the cracks on the walls. This will inevitably destabilise the trees and might lead to sudden collapse of both the destabilised trees and walls. Having regard to the above considerations, the trees had to be removed before the full onset of the wet season in the interest of public safety.
The Government understands that the public love and care for trees. In the past two plus years, we have actively explored different options to retain the two trees as far as practicable, including installation of props to support the tree trunks. We have also studied the practicability of installing steel cables as proposed by the HKU. Due to limited space for anchorage, the leaning walls and its overall unstable structure, it would not be feasible for the walls to bear the pulling force of the steel cables. Moreover, as the roots of the trees are already wrapped around the walls, there is plausible risk of the walls and trees collapsing together. Therefore, installing the steel cables cannot reduce the risk of collapse of the two trees and the wall. In view of the heavy traffic and high pedestrian volume along the narrow Bonham Road, it is not appropriate to place large props to support the two trees which may be weighing several tons.
On April 26, the Tree Management Office of Development Bureau invited experts of the Urban Forestry Advisory Panel to conduct a field trip to stonewall and wall trees in Hong Kong, including the two trees on Bonham Road, and broached the proposal of tree removal. Panel members agreed that alternative measures to retain the trees were not practicable, and their removal is necessary in view of the danger they pose to public safety.
In consideration of the heavy traffic and high pedestrian volume on the narrow Bonham Road adjacent to the two trees, and recognising that the proposed mitigation measures might not be able to reduce the risk of the collapse of the two trees and walls, the Government proposed to remove the trees to protect public safety. The proposal was submitted to the Food, Environment, Hygiene & Works Committee (the FEHW Committee) of the C&W DC (http://www.districtcouncils.gov.hk/central/doc/2016_2019/tc/committee_meetings_doc/FEHWC/13792/20180517_FEHWC_Paper_39_2018_R1.pdf). The paper, which contains photos showing the defects of the trees, details the reasons for tree removal and provides the relevant tree assessment documentation. On May 17, the Government representatives also attended the meeting of the FEHW Committee to explain the proposal, as well as communicated with other stakeholders, including the HKU, nearby schools, and residents, etc. through various channels to explain the reasons of the proposed removal works, particularly the importance of protecting public safety.
There was comment that the lack of signs of decay in a cross-section of the tree stump indicated that the trees were still healthy. It should be noted that the decayed parts are below the cross-section. From the professional point of view, the health conditions of the trees are reflected by other signs, such as the sparse foliage and relatively low live crown ratio, etc. We must point out that the Government has considered various factors in deciding to remove the trees, including the stability of the trees and supporting wall, the health and structure of the trees, their location, utilisation of affected facilities, and the practicalities of alternative mitigation measures, etc.
The Government cherishes our trees, but is also mindful of the threats unhealthy trees may pose to life and property. Noting from past cases, tree failures are always sudden, and there is no way that pedestrians and vehicles can escape when tree failure occurs. Therefore, when a tree becomes an overwhelming risk to the public, the Government is obliged to remove it to ensure public safety.
