Original: As part of the Streets Ahead contract, the city’s street tree stock will be managed and maintained over a 25 year period to ensure a varied and suitable stock of street trees for generations to come.
Simplified: As part of the Streets Ahead contract, the city’s street tree stock will be managed and maintained over a 25 year period to guarantee a varied and adequate stock of street trees for generations to come.
Simplified: As part of the Streets Ahead contract, the city’s street tree stock will be managed and looked after  over  25 years to allow a varied and suitable stock of street trees for years to come.
Simplified: As part of the Streets Ahead contract, the city’s street trees will be managed and maintained over a 25 year period to allow a varied and suitable selection of street trees for years to come.