Thursday, September 22, 2016

The Secret Life of a Shape-Shifting Weed (Solidago nemoralis)

I wondered why I had a peculiar love for
this humble plant. Sometimes, when we feel
emotions, it takes time to figure out why.

If you’re working to save ecosystems – 
sometimes a seemingly insignificant plant or animal pops out of the background and begs for attention. Maybe some important secrets are lurking in that overlooked species.

A little elf-capped cutie 
(gray goldenrod - Solidago nemoralis
did that for me recently. It was behaving
strangely.  I had been slow to notice.

I’m the steward of Somme Prairie Grove. 
What stewards think can change the ecosystem. 
A steward learning something new
 – and acting on it –
can make the difference between life or death
for hundreds of species of now-rare
animals and plants.

Stewards in training, Andrew, Josh, and Stephanie are thinking about gray goldenrod with me.
(Note the "insignificant" little yellow flower-heads, scattered in the grass behind them.)
It takes a village (of thinkers) to manage a delicate ecosystem as well as it deserves.
More about what these stewards are thinking comes later in this post. 
What was it – about this shrimpy goldenrod??? Yes, it is perky and has an adorable little "elf cap" top. But there's got to be more to love than that.

It's a little tyke. Not even coming up to your knee.
So what's so great about it?
Gray goldenrod glows with health toward the end of the year, when many species are looking moth-eaten and faded. As with the gentians and asters, its blooms mean cooler weather – the flowery grand finale of the growing season. But I don't fall in love with all asters and goldenrods.

Walking through Somme Prairie Grove last week, I decided rashly to drop the "more important" work I was doing and think about this plant.

Is this species increasing or decreasing under our restoration efforts? If so, is that good, or bad, or what? Is it a weed and thus will decrease if we're doing the right stuff? Many field guides call it "old-field goldenrod" and list its habitat as beat-up sterile pastures. It’s largely absent from many older “restored” prairies.

But its habitat in the recovering grassland at Somme Prairie Grove includes many of the very "best" spots.

A quick check revealed my new love to be flourishing in a few small areas - but completely gone from most areas where it had been common decades ago. Some spots where it has disappeared are grasslands where we have worked the hardest - and seemed to be among our best. Is something going wrong that we haven't recognized?

Gray goldenrod was common here, as our records show. Now it's entirely gone
from this and some other plots, where we've especially focused "restoration" efforts.  
We had seeded very heavily in some of the areas where the gray goldenrod was once common. In the case of the area shown above, we now have dense dropseed grass and purple prairie clover blooming in August - but little blooming in September. Dropseed and prairie clover are much rarer plants and are thought to be associated with higher quality habitats, so perhaps the loss of the "weedy" gray goldenrod shouldn't bother us?

Very high quality grasslands are diverse and flowery all season long. That's the "pink of their cheeks." Bright color all season long indicates health. Most of the animals and plants of conservation concern depend on a habitat of high diversity, not just a few rare dominant species. Is it possible that a few highly competitive rare species are, over time, increasing and wiping out the diversity we're trying to restore?

But in other areas, where we'd seeded with a lighter hand (see photo below), we not only have lots of gray gold, but also increasing numbers of such rare and fine species as prairie gentian, cream indigo, alumroot, and scarlet painted cup.

Here gray goldenrod grows with purple prairie clover, dropseed grass,
 lead plant, and other diverse, quality species.  
But when I looked more carefully, I seemed to see something troubling in the highly diverse areas where the gray goldenrod still grew. Here we had thinly broadcast seed of the rarer species most typical of high quality grasslands. Most of the dropseed plants were still young and small. But where they were dense, the gray goldenrod (and perhaps much other diversity) was gone. Not good.

This photo, in one of the highly diverse areas, is troubling. The middle of the photo is dense dropseed grass
(with fine leaves that look a bit like seaweed or unruly hair). Around the edges of this dense grass are hundreds of gray goldenrods. But the dropseed, which seems to eliminate the gray gold and much else where it's dense, will be dropping large amounts of its own seed, all around, year after year. Are the days of diversity numbered here?
Is our gray goldenrod a "mine canary?" Does its loss represent an easy-to-see trend that we need to better understand? In fact, could that explain my strong feelings for our dwindling numbers of little elf caps?

One way to test that hunch was to compare
what I was seeing here with one of the region's finest prairies, Somme Prairie Nature Preserve, less than a mile to the west.

So, as I often do, I made the pilgrimage
to quality - to see what it might tell me.
I have too much data in my head. I really couldn't remember whether gray goldenrod was in the Grade A areas.

I wondered. Were the books right about this species being most typical of old fields? Or does it have a "split personality" which allows it to thrive in old fields with rank weeds and - unlike all those weeds - also thrive in the highest quality prairie? As I approached the Grade A area, I felt the chill of suspense!

Yes! In the very high quality prairie, I saw gray goldenrod by the thousands.

I was thrilled to see the little darling thriving by the thousands among the rarest prairie plants. It can compete with weeds, and it can compete with the best of the best. But the message for our restoration work was clear. It can't compete in some areas that we thought were great. Gray goldenrod is a part of our "mentor" prairie, and its loss at some of "the best" areas at Somme Prairie Grove should lead us to ask questions, form hypotheses, and test them out. 

That afternoon I hiked the preserve with some people who are working to develop their expertise as stewards. We discussed many species and issues during that 2-hour session. At one stop, where for some reason I was inspired to take the photo below, we discussed gray gold.  

Remember Andrew, Josh, and Stephanie? I emailed to ask them what they remembered of our discussion at that place. Here's some of what they wrote back (slightly edited, so it might read as a dialog):

Andrew Van Gorp: You spoke about how most people in the field consider Gray Goldenrod to be a "somewhat weedy" native plant. Originally, it was all over the Somme Prairie Grove, but as the restoration progressed you began to notice that the Gray Goldenrod dwindled and only stayed around in areas where high quality plants were growing. 

Josh Coles: You went to Somme Prairie to test your hypothesis and found the gray goldenrod in all the greatest places. Someone asked about the Indian grass around us - and if it was a problem. You pointed out that in the gray goldenrod areas the Indian grass is thin, seems to be in check, and we can see right through it to the ground. Thus seedlings have a chance to thrive. 

Stephanie Place: We were standing near a little hillside that was notable for having less-dense tall grasses.  The ground was quite visible, and a healthy diversity of native plants was able to grow amongst it. This was in comparison to the areas of exceedingly dense and uniform Indian Grass that we'd just passed through. So you were talking about using the presence of the Gray Goldenrod as a cue to plant more conservative seed in that spot.

Andrew Van Gorp: We know for sure that some management techniques make large lasting differences - like culling over-populated deer or controlled burns. But we need to study interactions and phenomena to develop more advanced techniques, if we are to keep nature healthy. It may take a long time.

Yes, I pretty much agree. That's a good summary.

As the responsibilities and pleasures of being a steward pass from one generation to the next, we will continue to learn newer and better approaches. If we can recognize "symptoms" (like the presence of gray goldenrod) and match them with treatments (like investing conservative seed where they grow), then maybe we gradually improve at restoring health to small ecosystems (like Somme Prairie Grove) and, in time, to planet Earth, so we can maintain it as happily livable for us and our ecosystem friends.
pretty much

PS:  More detail on some of these issues is at:

PPS:  If you want to be sure whether you seeing gray goldenrod or some look-alike, the best character is the leaf shape. (Some truly weedy, unhelpful goldenrods may also be short and have the "elf-cap" look.) Gray goldenrod leaves are widest toward the end. They have kind of a fatter end. Subtle? To train your eye, see the photo below.

Tall Goldenrod                                                                              Gray Goldenrod
kind of a weed                                                                                  shape-shifter
widest in middle                                                                      widest toward the end

PPPS: I wonder if one of the experiments we should be doing with the restoration of degraded remnants is to seed initially with some of the less dominant conservatives ... and hold off until later with the dropseed, lead-plant, New Jersey tea, and other potentially over-dominant species. Hmmmm. I suppose that would mean coming up with a list of what those favored species are.