plant sampling at a solar installation

I’ve been doing some plant sampling around our solar arrays recently (see here for older posts on pairing native, pollinator-friendly plants with solar energy installations). We are trying to figure out which plants will grow given the strange soil, light, and precipitation conditions that happen between and around the solar panels. For example, directly underneath the panel there will be very little direct sun or moisture. There aren’t many (any?) plants in our region that evolved for those precise conditions.

There are many ways to assess the vegetation, but I won’t get into them all here. The growing season is for grabbing data before the opportunity passes, and the full analysis often has to wait until the dormant season.

One of my pet peeves is ecological initiatives (or any social initiative, for that matter) that fail to collect data after implementation to see if the intervention worked. There are many reasons this happens, but… happen it does. So I’m trying not to let old projects fall off the radar (and certainly can’t claim to be perfect in this regard). If it actually matters whether our work gets done or not, let’s get smarter and do better and learn from each other!

Back to plants…

One way to get an idea of the abundance or distribution of a plant is running linear transects along which you place some sampling plots. Like this:

Do enough of them, and you can get a pretty good approximation of what is happening, and better so than just walking through quickly and “eyeballing it.” Yes, Black-eyed Susan is showing up at your site, but was it a single plant, or is it showing up in almost every square meter? Has the Ironweed expanded its territory relative to last year, or is it contracting? Are there flowers available to pollinators from the very beginning of the growing season to the very end, or just a big flush in the middle? Repeated transect sampling gives us answers to these questions.

I used this method to count blooming species along shaded, partially shaded, and sunny transects. This gives some fine-grained detail as to what is thriving, where.

In the following photo, I’m directly underneath the center of the panels, so the plants are significantly thinner than in the full sun, and bare ground is present. This isn’t a bad thing necessarily, because most native bees species need bare ground for nests! Despite being relatively dry and very shaded, there are still some plants growing and even blooming.

I also try to establish a control group when possible. In this case, it’s the surrounding cattle pasture in which the arrays are located. Running a couple transects on adjacent ground gives me an idea of what floral resources are available absent this intervention.

In addition to the fine-grained detail, I also take a full account of any plant species that were present on the site, whatever their abundance. But… more on that another time.

However you slice it, paying attention is the first step. That calls to mind a Mary Oliver quote… “Attention is the beginning of devotion.”

Anyway… the real purpose of this post is to share videos and photos! We’ll start with this little surprise I found while cranking the solar panels up and down (we adjust the tilt 4 times per year to maximize energy production).

I can tell you that the treefrogs are VERY excited about pollinator-friendly solar. They are everywhere. And… of course that’s the whole idea of the food chain, of which we are a part.

I’ll finish with a gallery of photos. Enjoy!

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