'I have had students who have come out to Lantau and I have asked them to plant a tree with their hands rather than a spade and they were extremely reluctant. They wouldn't touch it. They just nudged it with their knuckles.'

The situation might appear almost comic.

After all, surely some of the most evocative images associated with childhood - immortalised in generations of washing power commercials - are of boys climbing trees, digging up worms and coming home plastered in dirt.

But there is a serious subtext to the condition whose growth has been accelerated by the twin effects of high-rise living and health scares over bird flu, swine fever and severe acute respiratory syndrome: it cuts people off from the countryside and results in the neglect of rural areas, according to Mr Melsom and other experts.

'It is an extremely worrying situation if you have kids who are afraid of soil and afraid of trees,' said Mr Melsom, who with the government's co-operation arranges educational tree planting for students.

'I asked students in groups if they liked trees and the amazing answer came back time and again: 'No, we don't like trees'.

'Children are becoming disconnected from the Earth. This is one of the major problems. I ask students which level of flats they live in and they tell me the 8th floor, the 12th floor, the 34th floor.

'If they are not going to connect with the Earth as children, they never will. The early years are the most important to learn about nature.'

It is an assessment many academics agree with.

Researchers looking into the condition of biophobia describe it as ranging from discomfort in natural places to 'contempt for what is not man-made, managed or air-conditioned'.

US-based Ruth Wilson, a professor specialising in childhood development, argues that when a generation grows up suffering from biophobia, the effect on the natural environment can be devastating and far-reaching.

In an article examining biophobia and its opposite condition - biophilia or love of nature - Professor Wilson wrote: 'Physical manifestations of biophobia include ... blighted cities, polluted rivers and toxic air.

'Experiences during early childhood years give form to the values, attitudes, and basic orientation towards the world that individuals carry with them throughout their life.

'Early positive experiences with the natural environment have been identified repeatedly as one of the significant life experiences associated with responsible environmental behaviour.'

Hong Kong may already be paying the price for the creep towards biophobia through the annual damage caused by the hill fires, particularly at the time of the Ching Ming festival when urban families return in their thousands to their rural roots in the New Territories, according to Mr Melsom.

On the Mui Wo hillside, where for years students and volunteers have been helping him plant native Hong Kong trees, between 1,000 and 1,500 trees were destroyed in one fire on April 5.

'They represented several years of passion, toil and sweat,' he said.

'The majority of the trees we lost were native trees and they were beautiful trees.

'The frustrating thing is that the incident is treated as just another hill fire. I think the problem needs to be treated more seriously.

'If people realised that people were being prosecuted for starting hill fires, it would make them think twice. The environment is very precious. There were thousands and thousands of beautiful shrubs and trees lost just in that one fire.

'It was a beautiful area to walk in. It covered around four hectares and there were all these regenerating trees and all that rose myrtle that would be flowering now. All that beauty has been destroyed again for the next six years. It has been replaced by a singed and burnt-out moonscape.

'Some of those trees won't regenerate. The plants get weaker and weaker after each fire and eventually they die and are replaced by grass. It is a terrible cycle that is going on all the time.'

A mixture of education, prosecution and a broader policy of native tree planting as opposed to planting non-native trees which create 'silent forests' where no birds or animals live is needed to try to reverse the trend towards biophobia in Hong Kong, according to Mr Melsom.

'There are 400 native species of trees in Hong Kong compared to 33 species in the UK,' he said. 'We are very lucky with our biodiversity here.

'But if you look at the planting in towns all around the New Territories, the majority of trees are non-native. As a result, you get no birds or butterflies.

'People are being cut off from nature by the sheer scale of the planting of non-native trees. We need to put people back in touch with nature.'

The Agriculture, Fisheries and Conversation Department has, in recent years, stepped up its planting of native trees.

'In recent years, two-thirds of the tree seedlings planted in country parks are native species,' a spokeswoman said.

In 2008, she said, nearly 600,000 native tree seedlings were planted and carefully selected for the terrains they were planted in, with species including the Chinese hackberry, the Hong Kong gordonia, the chekiang machilus and the silky machilus.

Those saplings may be at an increased risk of hill fires, statistics suggest, however, with 23 hill fires around Hong Kong in the first four months of this year alone and year-on-year increases in the overall annual number of hill fires for the past two years.

Long-term success in the campaign to preserve Hong Kong's natural environment may ultimately depend on whether the current generation of schoolchildren can be cured of their biophobia and converted to biophiliacs instead.

The greatest hope, Mr Melsom suggests, would be more nature education in school curriculums.

'I do a lot of seed-sowing lessons and students can't get enough of it - they love it,' he said.

'It is the children who miss out on things like this who end up afraid of the soil. That shouldn't happen with any child.'