The reservation is an area on Earth which has been given over to the ler, at their own request. It is a 4200 square mile forest preserve surrounded by an eight-foot chain-link fence which is more of a border than an actual barrier.
The ler keep the reservation mostly overgrown and unkempt-seeming, as opposed to the highly agriculturalized and industrialized remainder of Earth. It is more scrubby near the fence, but further in there are dark pine forests, looking ancient but actually planted more recently, especially in the eastern part of the reservation.