Fire loops around the globe
Your planet has its landmass as a band around the equator.
(or, alternatively, there's [almost] no open water, poles are covered in snow, leaving only the equatorial zone available to the biomass)
Somehow, there are no large rivers.
(plants still need to get moisture, and there's evaporation, which means there ought to be rain- or snowfall, which usually means runoff, but fires tend not cross large bodies of water... figure this out).
The equatorial zone is dry-ish, and e.g. typically covered by grasses.
The fire started (magically in only one direction), spread the entire width of the equatorial zone, and continues to burn, e.g. westwards.
By the time the fire has reached it's origin, that part has already sprouted new mature (and dry) grass, with seeds either preserved deep in the soil, or spread by wind, or spread by birds or even migratory animals.
Thus the fire continues to burn in a circle around your planet.
The long-lived plants died out, what remains are grasses and maybe shrubs.
The plants have therefore evolved to live in this cycle, and so have the insects and the animals.
P.S. some math
Fire boundary speed: 10% of wind speed (https://link.springer.com/article/10.1007/s13595-019-0829-8)
Typical wind speed: 10km/h
Thus, for a planet the size of the earth, the fire circumnavigates in ~4½ years, leaving enough time for plants to germinate, go through several life cycles and accumulate large amount of stale, dry biomass.