As you look out at the Arctic tundra, it appears to be a smooth, flat meadow of grasses waving gently in the wind. Once you try to walk across it, however, you quickly realize just how wrong you were.
The northern slope of Alaska is covered with huge plains of arctic grasses.
The tundra is covered with small mounds of vegetation called tussocks. The tussocks, small bits of semi-solid ground, wobble when you walk on them, and it is often wet between them.Tussocks form when some kind of grass seed takes hold and grows in the wet swampy bog of the spring thaw. In the fall, the blades of grass freeze and die while the plant continues to live in the ground – just like the grass in your yard at home.
The following spring, the plant sends up more shoots in the middle of the old dead leaves from last summer.
That fall, the new blades of grass freeze and die, just like they did last summer.
The cycle continues. Each spring new shoots grow, each fall they freeze and die – just like the grass in your yard.
The difference here is that the old dead leaves don’t decompose. In most places dead organic matter like grasses and flowers would be broken down quickly by various small organisms and turned into soil.
In the Arctic tundra, however, the summer season is so short the organisms don’t have time to do their job. What would only take one year in most places to break down into soil can take many years in the far northern regions.
The tussocks then, are clumps made up of whatever new growth grew this year, the dead undecomposed leaves from prior years, and whatever soil the microorganisms have managed to make.