"Sere" as a reference of ecological succession is a new one for me. I remember learning it from an Edgar Allan Poe poem and have loved it ever since, evocative as it is of blasted landscapes (and perhaps hopes). One wonders if its application in an ecological sense comes as much from its descriptive allusion to 'dryness' as from the back formation from 'series'.

Mm--you mean its homophonicness? Sere/sear.

Or either that or sere, one. But I see that sear is a variant spelling. I had never run into it with that spelling before. The two words, sere and sear, 'burn or scorch the surface of (something) with a sudden, intense heat', are from the same OE word, sēar.