tundra ecosystem Tundra ecosysems are often underlaid by permafrost, with the result that drainage is bad and the soil may be saturated for long periods. It does not have a permanent snow-ice cover. Productivity is low in this biome because of the extremes of climate. envoPolar An ecosystem which 1) typically has monthly average temperatures below 10 degrees Celsius 2) has a low evapotranspiration ratio 3) is dominated by treeless terrain, covered by communities of low-growing vegetation such as dwarf shrubs, sedges and grasses, mosses, and lichens, 4) contains areas of soil underlain by permafrost with a thin active layer and 5) occurs in both polar and alpine regions (i.e., both high latitudes and high altitudes), and 5) does not have permanent snow or ice cover. SPIRE:Tundra terrestrial ecosystem