Territory and Municipal Services' Urban Treescapes manager Michael Brice said up to 150 trees had been stolen or destroyed in recent months, costing the government about $30,000 to replace them.

''I don't know what would prompt people to do this but what we're finding is that it's widespread and indiscriminate,'' he said.

Trees have had to be replanted three times on Ainslie Avenue due to repeat vandalism. New plantings there now have to be protected by chicken wire with a top on it.

Four English oaks, which were planted in parkland off Doonkuna Street in Reid a year ago, are the latest trees to be targeted. Two had their trunks snapped in half and the others were bent to such a degree they were not salvagable.

Five of the 16 red spotted gums on Captain Cook Crescent in Griffith were damaged by vandals this week. Eight of the 11 red spotted gums on Kootara Crescent in Narrabundah have also been vandalised.

Other recent examples were:

■ poisoning, severe pruning and complete removal of trees across Gungahlin;

■ removal and damage of new trees planted along Limestone Avenue;

■ removal and damage of new trees planted in Eddison Park, Woden;

■ removal and damage of 12 of the 32 trees along Boddington Crescent, Kambah;

■ severe pruning and removal of four new trees at the end of Pilbara Place, Fisher, and three of the eight trees planted at the end of Bannerman Place, Holt.

Anyone who damages a native tree faces a fine of up to $11,000 (up to $55,000 for ''corporations'' and/or one year in jail. All other trees attract penalties of up to $5500 for indviduals ($27,5000 for corporations) and/or six months' jail.

Mr Brice said in some instances it was believed residents did not want new trees - especially eucalypts - planted in their street because they grew too large, and didn't let the grass grow underneath. He said a letterbox drop was done in affected neighbourhoods and sometimes requests for trees not to be replanted could be met.

However, in the case of Boddington Crescent in Kambah ''there was an established native treescape so we're not going to put in ornamental pears in there''.

Other trees, such as crab apples taken ''almost overnight'' from the Federal Highway, were likely stolen for replanting elsewhere.

Mr Brice said the government had increased tree planting and it ''may be the more trees there are to be seen, the more there is to be vandalised''.

''Anecdotally a hell of a lot more damage is being done than ever before,'' he said.

''It's very frustrating. It's a waste of money because we have to go back and do it again and people, I think, are ignorant of the reasons we're planting the trees. It's for the benefit of the community, to beautify the city and improve its amenity.''

Anyone with information about the vandalism and theft of trees should contact Crime Stoppers on 1800 333 000 or Canberra Connect on 13 22 81.