Shoot and Rhizome-Root Standing Crops of Tundra Vegetation at Barrow, Alaska

The relationships between permafrost and aboveground and subsurface standing crops of tundra vegetation at Barrow, Alaska, were studied during the 1964 and 1965 growing seasons. Average aboveground accretion rates ranged from 3 to 97 g m-2 year-. The lower values resulted from heavy utilization of vegetation by lemmings in a year having a high lemming population. In 1965, average aboveground total standing crop (live and dead) varied among six sites from 74 to 266 g m-2. Average live subsurface standing crop in the same year was estimated to range from 735 to 1,435 g m-2 at five sites. Ratios of live subsurface standing crop to aboveground accretion varied from 30:1 to 45:1. Vertical distribution of live subsurface standing crop varied with both site and depth. At a site with wet, organic, shallowly thawing soil, 91% of the live subsurface standing crop occurred in the top 10 cm of soil. At the other extreme, at a site with comparatively dry, mineral, deeply thawing soil, only 69% of the live subsurface standing crop occurred in the top 10 cm of soil. Within the Arctic, presence of permafrost affects formation of vegetational standing crops. This effect is exerted indirectly through influences of permafrost on soil moisture, soil aeration, and soil temperature. Comparison of standing crop in this arctic tundra with those in an alpine and several prairie areas indicates that reduction of standing crop in response to the severe arctic climate occurs more above the ground than in the ground. This contrast with more southern latitudes suggests that the aboveground environment is comparatively more restrictive to growth at Barrow than the subsurface environment. As a result, permafrost does not appear to be the primary factor limiting growth of vegetation at Barrow.