Why do conservationists prefer sustainable forestry to clearcutting?
Clearcutting means "mass kill of trees."
Clearcutting means clearing of an area of forest. It does not matter if these are new trees or old ones. Foresters cut down all trees and remove roots of them. This action causes erosion, topsoil loss, climate shift (since forests regulate microclimates), loss of habitat (for birds, forest mammalians (such as bears), etc.).
Sustainable forestry removes only old or mature trees without harming new ones or forest habitat. Renewal is not harmed overall. Ecosystem functions continue.
That is why sustainable forestry must be preferred over clearcutting.