This is the 16250th most frequent Russian word.
растущей
Growing.
Here, 'растущей' is used as an adjective derived from the verb 'расти' (to grow) and agrees with 'силой' in case, number, and gender.
У меня есть дерево с растущей силой.
I have a tree with growing strength.
In this sentence, 'растущей' is used to describe 'популяции', indicating something that is in the process of increasing.
Она заботится о растущей популяции птиц.
She cares for the growing population of birds.
Here, 'растущей' refers to 'экономики' and implies an economy that is currently expanding or developing.