Overstory light/canopy experiment

One of the trends we're seeing is that, even in the hotter drier parts of the range, young redwoods are mostly not found in deep shade - - just not enough light, even though it is cooler and moister in those locations (the deep shade). But at the fringe sites (as opposed to up in Humboldt County for ex) we also don't generally see them in the open. Our measurements of canopy cover give a percentage - say, 67% of the open sky is covered by canopy. But that 67% could be arranged in different ways. You could have lots of little canopy openings, which would mean the site would be mostly shaded most of the day, or you might have relatively deep shade most of the day coupled with a big canopy gap for part of the day - that would mean that the site might receive essentially direct sunlight for a couple of hours. And... what is the significance of *where* a canopy gap is - is it better for it to be in the north part of the sky, or the south part of the sky? Our results so far suggest that having a big canopy gap makes seedling survival more likely than lots of little gaps, and we're working on the question of gap location.

So, we're doing a growth experiment. We have a bunch of seedlings (Sonoma County stock). in collaboration with a wonderfully helpful local nursery (because we don't have a deer-secure full-light location to run the tests in on campus right now), we're setting up a set of shade enclosures. We'll have full-light exposure for some seedlings, fully-shaded for some, half-day shaded with north exposure, and half-day shaded with south exposure.

A few weeks ago, the seedlings came in from Sonoma County...

 

lots of healthy little baby redwoods :)

 

For scale - the pot is about 3 inches in diameter

The week before spring break, we spent a big chunk of a day cleaning old 1-gallon pots and transplanting the seedlings.

 

Luna wants to help

For now, the transplanted redwood seedlings are resting in a semi-shady location to give them some time to adjust to the transplant process...

 

As well as doing the transplanting, we built four pallet tables and assembled the frame for the first prototype shade enclosure (here, without shade cloth) so that we could refine the right measurements and the necessary parts list. (Yesterday a small group of us back on campus cut the pieces to size and partially assembled the frames so that we can transport them up and install them in the next week or so.)

 

there will be three seedlings in each of the four squares on each pallet table (the squares are 2 ft X 2 ft; each structure overall is approximately 4 ft X 4 ft

Each seedling will be randomly assigned to a particular light treatment, and we'll be measuring growth every two weeks to see how they are responding to their particular conditions.