Building an experiment, controlling the weather

This summer and fall I established an experiment that will hopefully become one of the major components of my dissertation. My current interest focus on how forests regrow after wildfires, and in particular how the weather patterns the years after a fire (for example, the current California drought) can have long-term effects on that regrowth.

Previously this question has been addressed using observation, by sampling fires which burned in different years and correlating their regeneration with those years’ weather.  While this is a great approach, the data is often noisy and messy, with lots of complications from other factors (location, fire severity, weather in the years before the fire). So instead, I decided to control the weather.

The goal was to build some kind of shelter that would keep out rain and snow, thereby generating drought conditions. I would then plant conifer (pine and fir) seeds, some under the shelters and others outside of them, to test the effects of drought on germination, survival, and growth. Just to make things a little more complicated, I was also going to manipulate the presence of shrubs, which resprout in burned areas and can suppress conifer seedlings, either leaving them in place or clipping and herbiciding them.

After hours of meeting with professors, fellow students, family, and friends developing a (hopefully) structurally sound and cost-efficient design, I got to start building.

My site before building, with plots laid out with flags.

Transporting PVC pipe. This is less than half the total used for the project.

Shelter base. Note the small stakes marking each planted seed, and the 6″ trench around the perimeter.

I had to hack through larger shrubs in the way of the shelters.

Completed shelter skeleton, with corners lashed together with paracord.

 

Creative ways to hold chicken wire in place. Fortunately I got help for the rest of the shelters on this step!

One of the shelters and trenches with the herbicide treatment (no shrubs). Time for the final step–adding the plastic roofing!

15 yards of plastic sheeting (enough for one shelter)

For the first shelter, I spent an hour carefully tying down the plastic sheeting, an endeavor that involved temporary holds with duct tape and make-shift needles from spare wire.

 

Thank goodness one of my labmates suggested a much easier solution–zip ties!

The completed shelters looked stunning. After so many weekends of work, I was incredibly happy to be done. Now I just have to hope that they’re sturdy enough to hold through the winter!

 

The view from the inside. There’s just enough space for me to walk between the seeds if I crouch low.

In total, I planted 1152 seeds. I spent four ten-hour days on my hands and knees clipping and herbiciding hundreds of 1cm shrub stems. I dug and filled 80 meters of plastic-lined trenches. I built 8 shelters, which took 48 feet of rebar, 300 feet of plastic sheeting, 450 feet of chicken wire, 800 feet of paracord, and a third of a mile of 1″ PVC, cut into 312 pieces.

Most amazing to me was all the help I got, from family who lent tools to labmates who helped with the final building push, and the countless people who invested time and advice in the designing and planning. I found out on this project that it really does take a village. Thank you all so, so much.