Can ecophysiology link pattern to process or molecules to landscapes for the study of treeline responses to climate?

Alpine treeline ecotones (ATEs) have drawn considerable interest for their perceived suitability for evaluating climate impacts on landcover boundaries.  There are a number of examples in which landscape patterns of tree establishment in ATEs appear related to ecophysiological mechanisms.  Explanations for physiological relationships typically require that the precise factors and processes limiting tree growth or seedling establishment be identified.  However, assessing physiological limitation for treeline hypotheses can be problematic because compensatory physiological adjustments may mask limiting factors and processes.  Alternative approaches to detecting physiological limitation are needed in the search for mechanisms underlying treeline responses to climate.