THE DISTRIBUTION OF HIGH-MOUNTAIN VEGETATION IN RELATION TO SNOW COVER - PENALARA, SPAIN

This research examines how snow accumulation, and erosion processes as sociated with it, influences the distribution of vegetation. Studies w ere conducted on Penalara Massif (2428m above sea-level (a.s.l.)), in the centre of the Iberian Peninsula (40 degrees 50'N, 3 degrees 58'W). The designated area is on the eastern slope between 1800 and 2400m a. s.l. A detailed vegetation map was developed and was used to select tw o key areas in each of the three altitudinal zones, located between 18 00 and 2000, 2000 and 2200, and 2200 and 2400m a.s.l. Each key area wa s determined in relation to the highest concentration of contrasts in vegetation in a limited space. The authors examined the most unstable landforms, the areas with the sparsest vegetation and the zones that h ad the greatest snow accumulation. Once these three criteria were supe rimposed, area types emerged that showed a high sensitivity to erosion . Each area was divided crosswise into two sections. A detailed study of each section was conducted and included the analysis of landforms, the application of inventories to strategic plots to determine the dis tribution of plant species, and the monitoring of active erosion proce sses and snow conditions from 1991 to 1995. Results showed that if the relief is uniform, vegetation tends to be distributed in homogeneous altitudinal belts. However, if the terrain is marred by obstacles comp osed of loose sedimentary material that descend in the direction of th e slope, the snow action will become an important factor in the distri bution of vegetation. The plant associations will colonize in belts th at run parallel to the slope. (C) 1997 Published by Elsevier Science B .V.