Created in collaboration with Swedish ornithologist Ulf Öhman, the hotel room was designed to immerse guests within the forest site, which is near the village of Harads.
"I got to spend a few days and nights in some of the Treehotel rooms right before the pandemic, and left with a sense of rejuvenation from complete immersion into nature," said BIG founder Bjarke Ingels.
"I couldn't help wondering if there was a way to take the immersion one step further – and almost instantly the idea of inviting not only the human visitors but also the resident bird and bat population to cohabit a spherical swarm of nests came to life."
The hotel room, which is suspended between two trees, is contained within a largely glazed cube. This cube is surrounded by a metal grid that supports 350 birdhouses of different sizes to create a spherical form.
"After our first conversations with Ulf Öhman from Norrbotten Ornithological Association we were relieved to learn that birds don't drop where they nest – so there is hope for the glass to remain clear within this cloud of aviary architecture."
The 34-square-metre Biosphere treehouse at the Treehotel is accessed across a suspended bridge that gently slopes upward towards the room.
It contains a double-height living space that has large windows for observing the birds and the surrounding forest, alongside a toilet and shower room.
A double bed is raised above the toilet and accessed via a stepladder from the living space.
The interior is coloured almost entirely black and several lights in the shape of the treehouse hang from the ceiling.
The hotel was covered in different-sized birdhouses to encourage a wide variety of birds to nest.
Along with creating an interesting experience for guests, the room is hoped to help increase local bird populations, according to ornithologist and Norrbotten Ornithological Association chairman Öhman.
"Inventories in Norrbotten County, carried out both by us as ornithologists and by the County Administrative Board, show that a number of different bird populations are decreasing," he said.
"Forestry has led to a reduced number of natural holes in trees where breeding birds nest. The installation of bird nests is therefore an important measure to take."
Öhman also hopes that visitors to the hotel will be encouraged by the experience to install birdhouses when they return from holiday.
"Demonstrating the use of bird nests and feeding, not just at the Treehotel but for people to install near their own homes, is valuable," he said.
"An initiative from Treehotel to take such measures may inspire their visitors to do the same."
BIG's Biosphere is the eighth treehouse to be installed at the Treehotel, which is located in remote woodland in Swedish Lapland.
Founded by Ingels in 2005, BIG is one of the world's best-known architecture studios. Other recent projects by the studio include the Bay View Google campus in California's Silicon Valley and the "world's most environmentally friendly furniture factory" in Norway.
This week the studio unveiled its design for the National Juneteenth Museum in Fort Worth, USA.
The photography is by Mats Engfors/Fotographic, courtesy of BIG.
Collaborators: Ulf Öhman, chairman of the Norrbotten Ornithological Association, Ateljé Lyktan, Vittjärvshus
Partner-in-charge: Bjarke Ingels, João Albuquerque
Project leader: Geoffrey Eberle, Angel Barreno Gutiérrez
Project architect: Francisco Abajo Duran
Team: Eszter Olah, Ragna Nordstrom, Pawel Marjanski