Figure 1. Most projections of range shifts (a) only include macroclimate (blue line), which varies predictably with elevation, and thus range shifts are commonly predicted beyond current upper elevational range limits (blue seedlings). However, it is ultimately successful establishment (i.e. success in early life stages) in response to microhabitat (dashed green line), not macroclimate, beyond the current range limit that will determine if a range shift is facilitated (b; green seedlings) by suitable microhabitat (dark green) or is constrained by unsuitable microhabitat (c; light green). Darker colors in both blue (macroclimate) and green (microhabitat) lines indicate increased suitability for establishment.