The authorities who develop such plans and visions should be commended as they have good intentions for the city and the people who live within it. Such plans and visions are incredibly important for cities, particularly with the introduction of more than 1 million people per week into cities across the world. Sustainable urban development is one of the greatest challenges facing mankind. The decisions we make now about planning and management of the urban tree canopy are likely to have serious implications for the environment and societies that rely upon it.

It is advisable to involve the community in the development of plans that have important implications for them. Was the urban tree management plan referred to for Hanoi open to comment by the community? Such processes can yield surprising results with comments received by people who have a particular area of expertise or see the plan through a different set of eyes. This process is also important as it allows people within the community to have some ownership over the decisions made and helps to avoid problems such as those that have arisen recently with the removal of large trees throughout Hanoi. These opportunities may also save considerable sums of money and result in more efficient processes. For example, articles published in Vietnam News have referred to the ‘coding of over 44,000 trees to build a software program of urban tree management.’ In our experience many governments throughout the world have embarked on such ambitious endeavours to find the outcome has been very expensive to achieve and has not been utilized as it is not user friendly. It is important to engage widely in such decisions to learn from the mistakes that have been made by others and improve upon them.

Questions must also be asked about what traits are deemed to be unsuitable for Hanoi’s urban trees. The removal of iconic trees such as the magnificent African Mahogany because they are deemed to be ‘not safe around residents due to their fasciculate roots and susceptibility to failure during typhoon season’ must be based upon sound science and assessment of tree risk by experts, not simply based upon opinions. The question must be asked as to how many people have been seriously injured or killed in Hanoi over the past 10 years as a result of such failure of this species?  It would be very interesting to then compare this to the number of people seriously injured or killed on motorbikes in Hanoi in the past 10 years, or the number of people who have died from smoking-related illness. We would suggest that the figures for motorbikes and smoking are much higher. Do we therefore ban the riding of motorbikes or smoking of cigarettes to improve safety for Hanoi residents?  We must look at the costs and benefits of each. The benefits provided by these large trees would far outweigh the costs. The reduction in air pollution, the provision of shade and cooling, the habitat for fauna, the spiritual connection and well-being to residents, the reduction in noise pollution, the capture of polluted storm-water, and the capture of CO2 and provision of oxygen. In comparison, motorbikes although essential for transport produce a large amount of pollution and congestion on the roads, and cigarettes provide no benefits and only costs to health.

It is also important to understand the causes of decline in health of urban trees, how to prevent the development of hazards, and how to mitigate risk. Diagnosis of the cause(s) of decline in health of urban trees is complex but it is essential if successful management of this decline is to be achieved. Over recent years we have witnessed the premature decline in health of many urban and heritage trees throughout Vietnam. Signs and symptoms observed include an array of pests and pathogens, however, the initial cause of the onset of decline may have been severe damage to the root system or catastrophic pruning of the crown, enabling the entry of these pathogens and pests. Sometimes by the time we have been asked to assist, it is too late, other times not. It is always much more successful and cost-effective to prevent the initial damage to the trees than attempt to cure or mitigate the problem. Images of trees shown in recent articles that have been selected for replacement of Hanoi’s existing tree population are highly unlikely to live long, healthy lives and provide any real benefits to the city’s residents. In contrast, they are more likely to lead to hazards and increased risks and require expensive maintenance, management and eventual replacement.

Articles have identified the spritual connection to trees.  This is a reminder that trees are not simply trees. I was reminded of this during a visit to a pagoda in a country village of Vietnam. I was asked to save two very old (300+ years) Bombax trees at the entrance to the Pagoda, as they had suffered a severe decline in health over recent years. The Buddhist monk at the temple explained to me that these were not simply trees, they were like old people with their own souls and it was very important that I do everything I could to prevent their death. Unfortunately my efforts were too little too late and the trees died. This was an incredibly sad moment for the local people, the Buddhist monk and myself. I feel the same sadness when I read about and see the results of the recent removal of many large trees in Hanoi and other Vietnamese cities. I see a completely unsustainable approach that will lead to a great deal of sadness in the future, and a very sick and more hazardous tree population. I also see that many of the replacement trees are totally unacceptable. This must be stopped and future management of urban trees throughout Vietnam must be based on sound science, knowledge and experience, not misinformation and fear. There is a great need to adopt new technologies for conducting precise diagnosis, monitoring and management of urban trees to achieve sustainable urban forest management in the future.