During the Ecology phase, Harvest levels of particular resources change. This happens in two steps.

First, move the Harvest markers on each Harvest track, depending on the number of tribers placed on the spaces marked with a sickle corresponding to each resource.

• If no triber has been sent to gather a given resource this season, the Harvest level of this resource increases by 1.

• If exactly one triber has been sent to gather the resource, the Harvest level remains unchanged.

• With 2 or 3 tribers, the Harvest level decreases by 1 or 2, respectively.