Plant functional traits are important parameters tofunctionally classify species as well as communities and tosubsequently approach ecosystem processes. Knowledge of theseprocesses becomes more and more important, especially as with theclimate change issue considerable migrations of species andcommunities are expected. This work presents a study, recentlycarried out in the C¢rdoba Mountains (Argentina), which revealednew findings. Intra- and interspecific differences of 7 plantfunctional traits (leaf area, specific leaf area, leaf dry mattercontent, plant height, leaf thickness, leaf tensile strength andfrost sensitivity) were analyzed in pairs of functionally relatedspecies along a 1500 m altitudinal gradient. The results arecompared with previous studies and discussed in an ecologicalcontext. Furthermore possible consequences for plant migrations andspecies distribution due to climate change are discussed. Inaddition I provide a synopsis of altitudinal differences in 70plant functional traits comprising 57 previous studies. The book ismainly addressed to researchers working on functional plant ecologyand climate change effects.