Some species of springtail can be reliably found in certain locations, e.g. Podura aquatica on the surface of ponds and puddles, Entombrya nivalis on tree trunks, etc. But most species can turn up anywhere where there is a suitable environment, e.g. enough moisture to prevent desiccation. For these species, "Everything is everywhere but the environment selects" seems to apply. But considering how small springtails are, how do they get everywhere?
Steve Hopkin (Hopkin, S.P. (1997) Biology of the springtails: (Insecta: Collembola) OUP Oxford) quotes examples of Hypogastrura socialis migrating more than 300 m in a single day using the sun as a navigation aid, and species of Entomobrya, Onychiurus, Sminthurus and others being captured on sticky traps or nets towed from aircraft at heights of over 3000 m. At certain times of year some species are known to ascend to the tree canopy and can then presumably be blown considerable distances on the wind, easily crossing barriers such as roads and rivers.
Never underestimate a springtail!