The orange box belongs to the National Incident Radio Support Cache (NIRSC). It's a relay station that the NICC owns and local incident commanders can order. It's a repeater for the USFS firefighters.
When you think about wildland fires, they are usually in remote places and geographically difficult places (lots of valleys and large areas for example). So for the fire commanders to keep all their people in touch repeaters are exactly what is needed.
The reason you see a yagi on that one is the commander base is probably fixed and that is aimed towards it. There is vertical antenna on the top with four ground radials. That looks to be probably a 2m system. What I'm not clear about is how it's powered and recharged. My guess is someone hikes up there periodically and swaps a battery. Or there might be solar panels sitting some place else?
This is the sort of thing on a smaller scale that was proposed for Cruise Moab, a temporary portable repeater. It's for an unexpected need like this why people like Groucho, Seldom Seen and I are obsessed with tinkering with antennas and radios and batteries and portable and mobile operations. That geeky PVC pipe and THHN wire rat's nest in my garage is a hasty 20/40/80 inverted 'V' type NVIS antenna that I can fit in my truck. No need for grid power and infrastructure to talk within about a 500 mile radius. I tinker with talking to AMSAT satellites and SOTA because being able to track and communicate with a MEO microsat using a 7-element beam and 5W HT sure hones your skills at low power, very portable operations...