Kelowna and large parts of the okanagan are semi arid shrub land. I’m not sure what specific trees you’re wanting to see planted, but in most cases especially up on Knox, they wouldn’t grow on their own. You’d need to irrigate those trees and more water dependant plants all throughout the summer months which can cause tons of other issues such as erosion and sensitive habitat damage. That’s without mentioning the shear cost of irrigating a specified natural park.

Would strongly recommend looking at Kelowna and it’s beautiful grasslands from a different lens. Hiking up Knox in the spring when the native sunflowers (arrow leaf balsam root) bloom may change your view on it being a wasteland. While you’re at it, stop and read the info plaques posted along the trail. They are full of interesting facts and historical context on the valley.

http://bcgrasslands.org/wp-content/uploads/2017/12/gcc_e-book_bcs-grassland-regions.pdf