Low current input source - current limiting resistor for z-diode needed?
On one hand, if the resistor is omitted, your supercap protection will work more reliably - allowing high voltage spikes to last for shorter periods of time by passing more current though the Zener. This could in turn destroy the diode.

On the other hand, by including the resistor, you will save the diode from self-destructing, but expose the capacitor to longer over-voltages.

Anyway, I would leave the resistor out, since it's the capacitor you want to save, not the diode.