Bromley is one of several boroughs across the capital now losing trees faster than replacing them, statistics show.
The new data was obtained by a Freedom of Information request lodged in February by London Assembly member Jenny Jones.
It has highlighted over recent years more street trees have been removed than added in seven boroughs, with News Shopper area Lewisham, as well as nearby Croydon, also suffering.
Figures for Bromley note a net increase in 2010/11, but over the last two years positive work has been reversed – 142 more have been felled than planted.
The Green Party representative is worried by the trend and has concerns over the environmental impact.
She said: “At a time we should be preserving and building up our street tree stocks to help cool and combat the health impacts of heatwaves, a number of boroughs are going backwards, chopping down more trees than they are planting."
The Mayor of London, Boris Johnson, is said to have aims to increase tree canopy cover by five per cent by 2025, but Cllr Jones AM is questioning the target.
She added: “It is not clear how this will be achieved, nor how this is targeted towards the most built up locations where heat island effect is most pronounced and the risk to vulnerable people is greatest.”
Responding to the comments, Cllr Colin Smith, deputy leader of Bromley Council, said: “What a peculiarly downbeat and negative outlook for the Green Party politician to adopt."
He added since 2002 Bromley has seen over 2,000 street trees put in place and underlined investments in the area.
Last month the authority announced hundreds of trees are to be planted in the borough in a £100,000 project following many falling during last winter's storms and gales.