You just have to look at how utterly the Harz pine forests have been completely destroyed by the bark beetle to see what monocultures get you. It's just huge swaths of lands filled with nothing but dead trees
Translation is probably Boom-bust cycle (literal: swine cycle?)
https://dictionary.reverso.net/german-english/Schweinezyklus for some rather poor usage examples
Loss of those trees was an economic disaster. I’m not sure it’s an environmental disaster yet - especially as replanting seems to be with better reference to the agro-climatic zone.
Given that most of the trees lost were in the nature reserve, the economic impact is somewhat limited.