The Best of Youth Begins in Saihanba

Feng Jin, a future person, follows Feng Cheng, the protagonist of The Most Beautiful Youth, to the harsh Saihanba plateau to plant trees. Just as Feng Jin thinks his whole life will be spent reforesting the place, what the heck? How did Guangu Shenqi and Hu Yifei end up here? Aren't they characters from Love Apartment? And what's with the water plant built by people from the capital? Who in their right mind builds a water plant in the desert?