A new study reveals that timber plantations can have negative impacts on the environment.

The Commonwealth Scientific & Industrial Research Organisation (CSIRO), which completed the study, said although plantations help to lessen the effects of greenhouse gas emissions, they can also stop river flows and increase salinity.

CSIRO researchers found that farmers in Victoria and South Australia had noticed a reduction in water run-off onto their farms following the creation of plantations nearby.

The study shows an average of one in eight streams dried up for one or more years about 10 years after the extensive establishment of plantations, while stream run-off had halved following 20-25 years of plantation growth.

CSIRO said plantation locations need to be carefully chosen.