Neither land nor water
Why Do Wetlands Matter?
A swamp looks like waste ground. It is one of the hardest-working pieces of landscape there is.
-
Step 1 of 5
Waterlogged mud has no air in it.
Water fills the gaps between soil grains and drives out the air. Roots and microbes that need oxygen cannot work, which makes wetland ground unlike ordinary soil.
-
Step 2 of 5
So dead plants pile up instead of rotting.
Rotting needs oxygen. Without it, dead plant material just accumulates, layer on layer, sometimes for thousands of years. That pile is peat.
-
Step 3 of 5
They swallow floods.
A wetland can take in a huge volume of water and let it out slowly over days. The same rain arriving on hard ground goes straight into the river all at once.
-
Step 4 of 5
And they clean the water.
Slow water drops its sediment, and wetland plants and microbes take up the nitrogen and other chemicals dissolved in it. Water comes out clearer than it went in.
-
Step 5 of 5
Draining one lets the carbon out.
Drain a wetland and air reaches the peat for the first time in centuries. It begins rotting, and thousands of years of stored carbon goes into the air over decades.
Peat preserves things extraordinarily well. Bodies, tools and butter thousands of years old have come out of bogs almost intact.
The short version
Wetlands soak up floods, filter water and lock carbon into waterlogged peat that only rots once it is drained.
Try it yourself
Squeeze a wet sponge and a dry one under a running tap. The wet one still takes far more before it overflows.