Gardeners are immersed in spring planting right now, having waited for soils to warm up and dry out a little. NOSC, on the other hand, tries to get all their planting projects done early, adding thousands of bareroot plants to floodplains to provide shade for streams and improve riparian wildlife habitat. Last month, when I helped 7^th graders install their Chimacum Creek Real Learning Real Work plantings, I noticed that the holes that students dug immediately filled with water and wondered how riparian plants survive seasonally flooded soils.

We all know that roots are responsible for absorbing water for plant growth, but roots also need oxygen to “breathe” (respiration). If water fills all the soil’s pore spaces for extended periods of time, anaerobic conditions develop. Wetland plants have evolved creative ways to deliver oxygen to roots in saturated soils. Those adaptations vary a lot depending on when soils are saturated and for how long.

Plants growing in regularly flooded soils often create bigger air pockets called aerenchyma in their roots and stems by breaking down cell walls to open up the spaces (like a house remodel). The plant uses aerenchyma to allow oxygen from tissue exposed to air to move down to the root system and also to move carbon dioxide and other toxic substances out of waterlogged roots. You can easily see aerenchyma tissue in a cross-section of a cattail or willow stem.

Plants may also try to avoid continuously saturated conditions by selectively growing on hummocks or rooting only in the top few inches of waterlogged soil where there is more air-to-soil oxygen exchange. Think of shrubs clustered on wetland hummocks, or salmonberry’s very shallow root systems.

Plants may also grow special roots called adventitious roots that sprout from stem tissue above saturated soil or near the soil surface where there is more oxygen. Western red cedar branches curve down to the ground and sprout new roots from stem tissue.

Some plants even develop ways to transport and release oxygen into waterlogged soils around the roots in a process called rhizosphere oxygenation. Sitka spruce has the ability to do this when necessary.

Not all of the Real Learning Real Work students were digging water wells and getting muddy. It depended on where their plots were located and how much rain had fallen recently. Sometimes they found soils that were rocky and gravelly. Plants have adaptations for those conditions, too, but that’s a story for another day…

Find out more and apply online at https://ecology.wa.gov/wcc. Be sure to select the North Olympic Salmon Coalition sponsored crew on your application.

Last chance! Our salmon art contest closes April 30th! Calling all artists, of all ages, to submit salmon art! We've received beautiful paintings, photos, and poetry already. Will you be the one to expand that list? The winners will receive a prize! Winners to be announced in our May newsletter. Enter now for a chance win and the opportunity to have your art displayed by NOSC for all to celebrate.