The first tree

In 2871, a patrolling drone has made an astonishing discovery: the first tree occurrence in Antarctica.
The remote-controlled drone was sent to take some samples of grassy plants on Elephant island, to better understand their genetic diversity and habitat plasticity. During the sampling, scientists have noted the presence of a relatively large woody plant, growing between a group of Acaena magellanica. The plant was instantly identified as Salix alba, a species of willow that was introduced by humans in South Georgia island several centuries before. The "tree" was 5 years old, but it was only 40 cm high (16 inches), showing marked dwarfism. 

One month after the discovery, a research team was commissioned to monitor the presence of woody plants across the northernmost islands of Antarctica. The results were unexpected: willow shrubs were found in at least 6 separated localities on Elephant, Clarence and King George islands.
Research continued in the next centuries, showing a progressive south expansion of this dwarf willow. After less than 150 years, S. alba was able to reach the northern coast of Alexander Island, which is found 1000 km away from King George Island.

Seeds were mainly dispersed by strong antarctic winds, but also birds had a significant role, especially on long distances.  Species density was very low and extremely localized, due to both harsh temperatures and the absence of soil.
Willows were faster at colonizing the western coast of the Antarctic peninsula, mostly due to the mild winters and relatively warm summers compared to the eastern coast.
This tree-shrub has proven to be an excellent habitat-forming species in Antarctica: the "tundrification" process was greatly higher where S. alba was present, thanks to the production of high amounts of detritus.
The arrival of trees sets an important milestone in Antarctica: the endless winter was over... something very new was emerging.