Hello again.
Since it took me some time to figure these out, im posting them for everyone to save their time. Biome names are taken from wiki by comparing with map legend from here:
http://www.dwarffortresswiki.net/index.php/Map_legend , although there seem to be some discrepancies.
Sav and Volc are irrelevant to biomes in world editor.
By elevation: WaterElevation: 1 - 99
Low MountainElevation: 300 - 332
MountainElevation: 333 - 365
High mountainElevation: 366 - 400
Everything elseElevation: 100 - 299
By rain/drain: HillRain: 10 - 66
Drain: 50 - 100
Sand DesertRain: 0-9
Drain: 0-32
Rock DesertRain: 0-9
Drain: 33-49
Desert Badlands ARain: 0-9
Drain: 50 - 65
Desert Badlands BRain: 0-9
Drain: 66 - 100
Second Desert Badlands biome (per wiki), occupying higher drain areas
GrasslandRain: 10-19
Drain: 0-49
SavannaRain: 20-32
Drain: 0-49
MarshRain: 33-65
Drain: 0-32
The character is darker than marsh in wiki map legend and matches that of a swamp instead, but on wiki both marsh and savanna have the same characters, so im guessing this one actually is marsh.
ShrublandRain: 33-65
Drain: 33-49
SwampRain: 66-100
Drain: 0-32
Forest(conifer icon, probably means temperate)
Rain: 66-100
Drain: 33-100
Forest becomes Broadleaf in high temperatures, which makes it the only biome in world editor that is dependant on temperature. Im guessing that the character for Conifer actually serves for temperate conifer and broadleaf, and the broadleaf icon means tropical broadleaf forest, because thats what the rain/temp/drain stats suggest, and otherwise there would be no differentiation between temperate and tropical.
Forest(broadleaf icon, probably means tropical)
Temperature: ~ 60-75 (varies a bit for different drain values)