The incident happened at Rea Brook nature reserve in Shrewsbury.
Jim Goldsmith, countryside and green space manager for Shrewsbury Town Council, said: “We were alerted to somebody illegally felling trees in the local nature reserve on the section just behind Moneybrook Way on Friday, January 27.
“By the time our officers arrived, the culprit had made off and had left a number of trees both felled and partially felled. Not only is this destruction of vital habitat, it is also theft.
“The illegal work is also a danger to other members of the public as well as to the individual concerned.”
Town council staff have now tidied the area and have ensured that damaged branches left behind have been removed and the area has been made safe for members of the public.
Mr Goldsmith added: “We would like to remind our visitors that the removal of trees or timber, even dead wood from the ground, is prohibited on all town council-owned land.
“Where staff have removed trees, they will often leave piles of timber and branches as habitat piles, which are important features and are used by numerous invertebrates, small mammals, birds and fungi.
“In addition, the use of powered saws is quite obviously prohibited on our countryside sites.”
If anyone has information on this crime, call 101 or Crimestoppers on 0800 555 111, quoting crime reference number 22/9936/23.