Which of the following critiques of forestry’s impact on the physical environment is a positive effect?

It seems there is a contradiction in your question. Critiques generally refer to negative aspects or disadvantages of a certain subject or practice. However, if you are looking for a positive effect of forestry's impact on the physical environment, one could argue that reforestation efforts contribute to the removal of atmospheric carbon dioxide and the mitigation of climate change, thereby positively impacting the environment.

A critique is generally a negative comment or evaluation, so it is unlikely that any of the critiques of forestry's impact on the physical environment would be considered a positive effect. However, if you are referring to a specific set of critiques, please provide more details so I can assist you further.