Transverse pattern of vegetation on avalanche paths in the northern Rocky Mountains, Montana

Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} The pattern of vegetation on avalanche paths has usually been ascribed to the damage done by snowslides. In the northern Rocky Mountains the pattern of herbs, shrubs, and small trees appears to be more complex than could be accounted for by avalanche magnitude and frequency. The vegetation on one path in Montana illustrates that the topography of the path is a factor in the distribution of species. Three zones exist across avalanche paths: an inner zone of herbs and suffrutescent shrubs occupying a ravine, which is snow covered longer than elsewhere; flanking zones of dense shrubs and trees with flexible stems; and an outer zone of less dense shrubs that is more xeric. The pattern of vegetation seems to be due to avalanche-related stress rather than damage.