The dominant part of phase noise of High Q oscillator, for example xtal, is the AM noise, instead of PM noise???

From the pnoise(modulated) simulation of spectreRF,

For ring or LC oscillator, the most is the PM noise. It does match the theroy of cyclo-stationary noise, by ken et.
But for xtal oscillator, the AM noise is more than PM noise.

Is it because of xtal's chararistic of HIGH Q ???