pago-, pag- (peak) +
(Greek: a "peak", but used by ecologists in the restricted sense of "foothill")
Be aware that there is another Greek pago- unit that refers to "ice".
pagophile
In biology, thriving in foothills.
pagophilous
Biologically applicable to thriving in foothills.
pagophily
Plants or animals that thrive in foothills.
pagophyte
A specific reference to plants that inhabit foothills.