Who parks here?

These names are in the parking bays in Kings Wood where we parked for some night time orienteering. I thought they were the names of Roman emperors or similar and wondered why they should have their names in the car park???

Keen arborists among you will know that Pseudotsuga is a douglas fir, Cratageus is a hawthorn and Quercus is an oak. I was disappointed to find this out when I checked the internet and my dreams of roman ruins in the woods were dashed.