Most of the Juniper forests in Idaho are south of Boise in the Owyhee Canyonlands area.
https://fhm.fs.fed.us/fhh/fhh_09/id_fhh_09.pdf
Juniper is popular as a landscape tree and shrub in Boise.
There is also a restaurant downtown called Juniper
The forest above Boise is dominated by Ponderosa Pine.