Tree-hugger

A “tree hugger” (or “tree-hugger”) is an extreme environmentalist, so-named because many such activists hugged trees to prevent their removal. The term “tree-hugger” is cited in a 1960 novel and in 1965 news reports about a protesting group in Chicago. 
 
Other terms for an extreme environmental activist include “environazi,” “enviromarxist,” “enviroweenie,” “greeniac,” “envirotard,” “ecotard” and “climatard.”
           
   
Wikipedia: Tree hugger
Tree hugger can refer to:

. A slang, sometimes derogatory, term for environmentalists
. Chipko movement, an environmental movement in India
. TreeHugger, a sustainability website
. The Tree Hugger Project, Environmental Art Project
 
Merriam Webster’s Online Dictionary
Main Entry: tree hugger
Function: noun
Date: 1982
sometimes disparaging : environmentalist 2; especially : an advocate for the preservation of woodlands
 
(Oxford English Dictionary)
tree-hugger n. chiefly U.S. a person who cares for trees or the environment, an environmentalist (usu. depreciative); (also lit.) a person who adopts a position embracing a tree to prevent it from being felled.
1965 Appleton (Wisconsin) Post Crescent 10 Sept. 1/4 The battle was between the *tree huggers and the city. The city won, 100-0.
1977 Washington Post 7 Oct. (Weekend section) 1/1 Leaves are starting to turn now… Tree huggers predict colors will be most vibrant starting Oct. 15. (‘Tree huggers’ is what rangers assigned to the Washington area call themselves.)
1982 N.Y. Times 8 May 23/6 ‘Tree hugger’, some mutter, and I would say it myself before them. After all, I have not yet met an environmentalist who refuses to drive a car.
1990 R. SCARCE Eco-warriors II. viii. 157 Mahatma Gandhi’s spirit also resides in the Chipko Movement, India’s tree huggers.
 
Google Books
Our Daily Bread: a novel
By Kalle Päätalo and Richard A. Impola
San Luis Obispo, CA: Finn Heritage
1960
Pg. 259:
“Let’s go now, tree-hugger,” gasped one of them.
“The show’s over. Everybody beat it,” ordered the other.
 
Google News Archive
10 September 1965, Toledo (OH) Blade, pg. 10, col. 1:
Chicagoans Cling To Past In Vain
Road Crews Fell Park Trees Around Protesting Group
CHICAGO, Sept. 10 (AP)—The battle was between the tree huggers and the city. The city won, 100-0.
 
Google News Archive
23 September 1974, Montreal (Quebec) Gazette, pg. 28, col. 2:
Tree huggers save forest
NEW DELHI—(UPI) Women in a village in Uttar Pradesh state are hugging trees to save them from the saw.
 
When timber contactors’ teams come to cut the forests, women of Reni village, 150 miles southeast of here, embrace the trees until the lumbermen depart.
 
“All felling of trees in the area has stopped because of this Chipko movement, which seems to be spreading to other areas,” a forestry official said.