Using dyadic intervals, I can build a binary tree for $\left[0,+\infty\right)$ by having a node the $i$-th at level $l$ representing the range $\left[i\cdot2^l,(i+1)\cdot2^l\right)$ and has the $(i)$- and $(i+1)$ at level $l-1$ as children.

I would like to build a similar tree for $(-\infty,+\infty)$, but it is not clear to me how this can be done using a single tree. One solution would be to use two binary trees as described above, one for positive and one for negative numbers. Is there a solution that uses a single tree? The tree does not have to be binary, but it would be good if there is a bound on the branching factor.