conservationist

conservation +‎ -ist

conservationist (plural conservationists)

1. A person who maintains natural areas or protects threatened species.
2. Someone who advocates for these actions.
   • 2020 June 3, Andrew Mourant, “A safer railway in a greener habitat”, in Rail, page 58:

     Over the past two years, particularly in 2018, Network Rail has come under fire about its approaches to trackside tree-felling across its 52,000-hectare estate. Conservationists accused it of wanton destruction.

• environmentalist

• conversationist