Savi and the Memory Keeper by Bijal Vachharajani

Funny, thoughtful, and deeply moving-with a unique blend of fantasy and actual science-this novel explores both personal grief in the face of family loss and collective grief in the face of climate crisis, and how the only way to move forward is through friendship of all kinds.
In Shajarpur, everyone is always happy. The weather is always perfect. But newcomer Savi, a lonely teenager, doesn't know what happiness means anymore. If she were to make a list of things that were the absolute worst, moving to Shajarpur would be right on top. Well, right after missing her father, who just died of a heart attack.
As Savi grapples with loss in a strange new town, she discovers something startling. Not only can she communicate with her father's plants-all forty-two of them-she can talk to the giant ficus tree behind her school. Savi soon learns that Tree (as they are known) knew her father as well and that their friendship was at the heart of a magical network of animals and plants working together to protect Shajarpur.
However, Tree is in danger, along with everything else, and needs Savi's help. As she joins with all kinds of living things to save the town, Savi is shocked to find she is happy again, even if forces of nature are beyond her control.