Synchrony of species’ growth rates for each study area from IBM simulations across different landscape sizes when only demographic stochasticity is present (“No Comp. + No E.S. (D.S. Only)”) and when environmental stochasticity is also present (“No Comp. (D.S. + E.S.)”). The horizontal lines show the analytical predictions ℳD (dashed line) and ℳE (dotted line). The strength of demographic stochasticity decreases as landscape size increases because population sizes also increase. Theoretically, “No Comp. + No E.S. (D.S. Only)” simulations should remain constant across landscape size, whereas “No Comp. (D.S. + E.S.)” simulations should shift from the ℳD prediction to the ℳE prediction as landscape size, and thus population size, increases, but only if demographic stochasticity it strong enough to counteract environmental forcing. Error bars represent the 2.5% and 97.5% quantiles from model simulations.