Saturday, March 20, 2010

Planting trees for the ocean?

[Originally posted to MBA Student Oceanography Club (SOC)]
Carmel River Estuary

For two of our field activities, the Student Oceanography club has planted trees and removed invasive plants on a former artichoke farm that is now growing strawberries.  Huh?  What does weeding have to do with oceanography?  How do willows next to a berry patch help conserve the oceans?  Well it turns out that our efforts can help the ocean in a number of ways:

  1. Trees and other native plants produce habitat and foraging space for birds and insects.  Many of these, such as the ladybugs that we saw during our visit, eat crop pests.  When pest predators are abundant, farmers use fewer pesticides, reducing the amount of chemicals washed  into the sea.  Even though Serendipity Farms is an organic farm, the insectivore-friendly practices they are putting in place will have positive effects on surrounding farms, too.
  2. Trees and other plants absorb lots of nutrients in ground water, leading to cleaner water reaching rivers and the ocean.  While nutrients may sound like a good thing, excess nutrients in the ocean can lead to harmful algal blooms (see my post about dinoflagellates below).  This is especially important in agricultural areas where farmers add nutrients to the soil with fertilizers.
  3. By slowing down water running over the ground and protecting the ground from wind and rain, trees and plants also reduce erosion.  Less erosion means less sediment is transported to the ocean, where it can smother marine life.  Less erosion also means that rich topsoil is preserved, reducing farmers’ reliance on fertilizers.
  4. Trees create shade that keeps water in streams and marshes cooler.  Cool water increases dissolved oxygen levels and is crucial for the health of fish, such as steelhead that live in the Carmel River. Fallen trees also create hiding spaces and slow currents, making better habitat for young steelhead.  After growing up in streams and estuaries, steelhead become an important part of the marine food chain, feasting on plankton and small fish while providing food for larger fish and marine mammals.
  5. Finally, trees reduce atmospheric carbon through photosynthesis and sequester carbon in their wood.  Planting trees may be one of the most effective methods of taking CO2 out of the atmosphere in order to reduce the effects of global climate change and ocean acidification.

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