Heritage trees are being felled at a faster rate today than they were before the 2010 launch of a tree management office, the Post has found, a situation one expert called unacceptable. A review of 527 heritage trees, also known as Old and Valuable Trees (OVTs), on the government's register set up in September 2004 found at least 71 had since died or been removed. Of these, 41 had gone since the establishment of the office in March 2010 - an average attrition rate of 10 trees a year. In the five years before the office was set up, only 30 trees were removed - an average of six a year. Ninety per cent of the trees that died in the past four years were managed by the Leisure and Cultural Services Department, and 60 per cent were on Hong Kong Island. More than a third died of brown root rot disease, which has spread across the city. Last month Secretary for Development Paul Chan Mo-po declined a request by lawmakers to introduce a tree protection law, at a time when the government is also under pressure to ensure the safety of private trees after one fell and killed a pregnant woman in Mid-Levels in August. "The rate of OVT loss was unacceptable in the past, and is getting even more unacceptable in recent years," said Professor Jim Chi-yung, a tree expert at the University of Hong Kong. "The care of OVTs is the most sensitive indicator of the general standard of tree care. If they cannot even take care of our best, what can citizens expect in relation to other trees in our city?" OVTs are trees on government land selected for their old age (at least 100 years), outstanding form, rarity, and cultural and historical significance. Jim, a member of the expert panel set up under the office, said the office had failed to function. The office, headed by someone with the most junior civil service ranking, was set up to give recommendations and to coordinate departments on tree management after a sick tree in Stanley market collapsed and killed a student in 2008. Jim cited the example of a 12-metre-tall Chinese banyan tree at the entrance to the footbridge in Kowloon Park that links to China Hong Kong City shopping mall. Safety concerns were first raised two years ago. Then a few months ago a major crack was found on the tree and the Leisure and Cultural Services Department (LCSD) feared it would collapse. Panel members advised the tree management office to support the tree with metal props. But the office spent a futile two years trying to convince the various departments involved. The LCSD tried to save the tree by using six 4-tonne cables to stabilise it and pruned its crown to reduce its weight. But the tree was cut down last month. Asked why the experts' advice was not taken, the department said the design of the temporary propping proposed by its maintenance agent were considered "operationally not viable" and "visually intrusive" as the footbridge was used heavily by pedestrians. Jim said: "If designing a tree prop cannot be determined in nearly two years, it is understandable for citizens to be worried about the quality and timeliness of tree management and protection in our city. "Precious time to render the tree stable and safe sadly has been allowed to slip away in an apparently insouciant manner." It was the third heritage tree to be removed in the past two months. Another panel member, Ken So Kwok-yin, said he had also observed the increasing removal rate and the difficulties the office faced in asking departments to execute its recommendations. "The office is definitely responsible for its failure to improve the trees' health but the comparison of the removal rate may not tell the whole picture as some trees have fallen ill before the office's establishment." Both the office and the Leisure and Cultural Services Department said they were prudent in removing trees and had sought advice from experts.