The Collaborative International Dictionary of English v.0.48:

Alpestrine \Al*pes"trine\, a. [L. Alpestris.]
   1. Pertaining to the Alps, or other high mountains; as,
      Alpestrine diseases, etc.
      [1913 Webster]

   2. (Bot.) Growing on the elevated parts of mountains, but not
      above the timber line; subalpine.
      [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

alpestrine
    adj 1: growing at high altitudes [syn: alpestrine,
           subalpine]