When Active Management of high conservation value forests may erode biodiversity and damage ecosystems

The increase in extent and severity of disturbances such as wildfires and insect outbreaks in forests globally has led to calls for greater levels of “Active Management” (AM), including in High Conservation Value Forests (HCVF) such as old growth stands. AM includes such activities as thinning, selective logging of large trees (that are sometimes fire resistant), post-disturbance (salvage) logging, recurrent prescribed burning, and road building; singularly or in combinations. We urge caution when implementing these aspects of AM, especially in HCVF such as old growth stands, intact areas, and complex early seral forests. This is because AM may have substantial impacts on ecosystem conditions and biodiversity, and could amplify subsequent natural disturbances. We illustrate potential impacts of AM in HCVF in case studies from western North America and south-eastern Australia. AM has overlooked or downplayed collateral ecosystem damages in HCVF, including: (1) habitat needs of at-risk species, (2) thinning effects on ecosystem function, carbon emissions and biodiversity, (3) the role of stand-replacing or partial stand-replacing natural disturbances (e.g. wildfire, insect outbreaks) that produce complex early seral habitats, and (4) extensive road networks with associated impacts. We argue the underlying science to support AM may be lacking in some cases and that more scrutiny is needed to ensure objectives are supported by rigorous science, including transparency in identifying collateral damages and ways to mitigate them. Large reference areas such as extensive old growth stands are needed to assess the cumulative impacts of AM, especially in in HCVF where its potential effects on biodiversity are greatest.