Freshwater Ecosystems

The freshwater ecosystems described here are found in the tundra and boreal forest (taiga) biomes of the Palearctic and Nearctic Regions (the latter emphasized here). Since the substrata of most of the tundra and much of the taiga consist of permafrost, most of the water that reaches the surface as precipitation (rain, sleet, and snow) stays close to the surface (in some places, the subsurface soils may permit some penetration and underground flow of water in summer). This accounts in large part for the myriad of lentic (standing water) habitats so characteristic of both tundra and taiga. Another factor that contributes to the abundance of surface water on the summer Arctic tundra is the often gentle slope of the land. Rain and meltwaters tend to remain where they occur and to accumulate rather than run off. Nevertheless, there is slope, and water does move. In the solitude of the tundra, where the only sounds are the calls of the birds, the rustling of the breeze in the cottongrass, and the distant rumble of thunder, one can often hear all around the faint murmurs of myriads of tiny rivulets that are unobtrusively yielding to the pull of gravity. Water also moves on alpine tundra, but there in early summer, streams large and small tend to be full (of meltwaters from snow and glaciers) and fast because the slope is often steep.

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