I must caution against using the wiki page as reference: it was woefully inaccurate for .34.11 (exaggerated pasture requirements by factor two or three) and is completely obsolete now.
Elephants don't have an explicit "Grasstrample" entry, which i think means their value is "normal" (i.e. quite a lot). Explicit values are only used to specify that a creature has an "abnormal" effect on grass, for example for creatures that do _not_ trample grass (grasstrample:0). If there's no mention, it generally means a creature _does_ trample grass, and the value presumably depends on creature size.
Case in point: dwarfs have no "grasstrample" entry and they certainly do erode grass where they walk. Elves have "grasstrample:0".
I tried out two 10x10 undisturbed plots cleared of all vegetation:
a) underground room, dug out just before breaching the caverns
b) aboveground area, cleared via b-O (build dirt road)
I let both run for about 100 days. At the end,
a) had 30 tiles of "sparse", 19 of "normal" (i.e. without density indicator) and 10 of "dense" vegetation, two saplings and four bushes. 35 tiles remained naked loam.
b) had 14 tiles of "sparse and 4 of "normal" grass and 11 of bamboo of varying density (technically also grass but afaik not useable by grazers other than pandas); 33 tiles remained "furrowed" soil (all tiles are converted to furrowed when building). 13 tiles of the area were tree trunks or naked rock.
Assuming that "sparse" counts as one unit of vegetation, "normal" as two and "dense" as three, it looks like the underground area gained ~ one unit of vegetation per day. More likely, each tile had a 1% chance per day to grow something. The remainder of 35 tiles of naked soil after 100 days fits the prediction. Similarly, the 33 tiles out of 87 of furrowed soil suggest that furrowed soil "unfurrows" with a similar probability, and furrows must be gone before vegetation can grow.
I took stock of values every ten days, and the underground plot _did_ gain around about ten units of vegetation in each of those intervals. Since the aboveground plot had to first run off the furrows before anything could grow, direct observation of growth was not so conclusive there. Some biomes _are_ practically sterile where the original surface is concerned (deserts, wastelands), but from what i've seen, you seem to get perfectly normal (1% a day?) growth when you channel into the soil.
PS: if 150 "grazer" meant a creature has to eat a full "unit" of grass every 150 steps, that'd mean 8 per day. 100 tiles of grassland replenish one unit per day on average, so to replenish 8, you'd need 800 tiles of pasture (not even taking into account non-grass tiles like exposed rock, trees and bushes), roughly 28x28. Experience says a horse (grazer 120 in .34.11) didn't need 1000 but only ~60 tiles of pasture. Looks like the actual workings of grazing are still largely unknown and the extant theories are a long way off the mark.
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Topic: Grazer Formula (Read 1473 times)