Partial river flow recovery with forest age is rare in the decades following establishment

River flow responses to forestation at annual time scales The landscapes of the future might look very different to those today, and many have argued that increasing tree cover is essential to mitigate the worst effects of climate change. But forests affect many natural
processes, including water availability. We systematically reviewed the literature to determine how forests will affect river flow over long periods of time. Annual river flow declined significantly as forests aged, but the effect was smaller in drier years, suggesting that forests were reducing water use in response to availability. Forests planted on agricultural land also had smaller effects on river flow. In contrast to previous studies we found little evidence that the effects of forests on river flow will be reduced with age. These results highlight the importance of planning for reforestation at the landscape scale and taking local cultural and ecological contexts into account.

Bentley and Coomes (2020) Global Change Biology.