Swiss art curator Klaus Littmann planted 300 trees as a replica forest inside a football stadium in Austria in what he called a "memorial" to the environment in the age of the anthropocene.
"For Forest is very timely as it coincides with growing global discussions and activism linked to deforestation and climate change," Littmann told Dezeen.
The forest remained in situ so visitors could watch the tree's leaves turn from their summer to autumn colours. Afterwards, the trees were replanted close to the stadium as a permanent urban forest.
Artist and designer Lin transported 49 dead Atlantic white cedar trees into the middle of a park in Midtown Manhattan. The trees were felled and cleared from the New Jersey Pine Barrens.
"They had died off due to extreme weather events related to climate change: wind events, fire, sea-level rise, saltwater infiltration and bad forestry practices," said the artist.
Ghost Forest will remain in Madison Square Park for six months, with the dead cedar trees growing paler and more ghostly as the living trees around them change colour with the seasons.
British designer Devlin installed 400 trees in the courtyard of the historic Somerset House as part of the London Design Biennale.
Called Forest for Change, visitors walk through the forest to reach a clearing with pillars that display the 17 UN's Sustainable Development Goals.
"It's my hope that when you get to the centre, you're able to approach these really complex global problems without feeling so daunted or overwhelmed," said Es Devlin.
After the Biennale the trees will be donated to various boroughs around London and planted as part of the Queen's Green Canopy project.
Over a thousand pine seedlings have been planted in a miniature forest by Danish architecture studio EFFEKT as part of its exhibition at the Venice Architecture Biennale.
Called Ego to Eco, the tiny trees surround scale models of the studio's projects. A hydroponic grow table, controlled remotely from Copenhagen, will nourish the plants throughout the Biennale.
After the show, the 1,200 seedlings will be taken back to Denmark and replanted as part of an urban forestation project.
"Ego to Eco is built upon the idea of creating an exhibition with a lasting positive impact," said EFFEKT.
Design studio Superflux transported 415 pine trees damaged in wildfires to the Museum of Applied Arts. Visitors can walk through the trees to reach a reflective pool surrounded by live trees and mosses.
"Climate change is not a problem we can 'solve' but rather a predicament we must navigate with responsibility and urgency," said Superflux co-founder Jon Ardern.
After the exhibition, the living trees will be given to local schools to plant, while the dead burned trees will be turned into compost.