What a Difference a Rain Makes: The Dinky Track

The view looking south from the center of the 100-acre Dinky Track earlier this week

Barring a catastrophic dike failure (which we thankfully did not and should not experience), the thought that a single rain could cause flood damage to a wetland might sound strange. But the last line of my July 16, 2017 post (the day we flew seed over 50 acres of the Dinky Track) was pretty prophetic . . . to continue the biblical theme . . . "P.S. Thunderstorms are in the forecast again for this afternoon."

Just a few short hours after the seed rained down out of that plane, the actual rain came down. And it came down in big drops, close together. The thunderstorm was sustained and within a few short hours more than 2" of water fell. Usually, this wouldn't cause major problems with a millet seeding when water can be taken off a unit. But because we were just on the jagged edge of "dry" enough and because we couldn't get it dry quickly enough (in part due to extremely soft sediment holding moisture), we've now come to discover that much of the seed rotted. The landing strip of relatively bare mud above is a testament to too much water at just the wrong time.

Per usual in marsh management, one has to take some
bad (e.g. Swamp Loosestrife, above) with the good;
such is life in a world riddled by invasive species

But as is so often the case in nature, there is a silver lining. We had a hunch that the Dinky would respond differently to a late drawdown as compared to the adjacent Tower Marsh. That's why we flew millet onto 50% of the Dinky versus more like 15% of the Tower. What we didn't anticipate is that both units would show positive responses from the seedbed (the seeds naturally residing in the shallow soil).

Based on our hike earlier this week, the Dinky has much of the same nut sedge that we are observing next door (a good thing). Where the millet is lacking, we are also seeing other good pushes of smartweed and beggerstick (more good news). There are also some hints at some desirable perennials -- most notably soft-stem bulrush (again, a good thing).

We knew we were going to be dealing with some invasive loosestrife, both purple (below) and swamp (left, and in isolated stalks to the right above). As we discussed from early on, the purple is largely being held in check by a friendly beetle. There are a couple initially daunting stands in the Dinky now, but as the photo below illustrates well, the beetles are doing their jobs. And as for the swamp loosestrife, they are really only prevalent on the very tops of old, rotting root clumps (on "high ground" islands no more than 18"x 18"). We are scratching our heads a bit as to the best management approach with these buggers (no, the beetles have no appetite for swamp loosestrife), but the good news is, they don't tend to spread overly quickly, and they are really only sporadically present in most of the unit.

A fairly sizable (~1 acre) stand of purple loosestrife trying to establish within Phragmites that was sprayed in 2015;
note browning and highly stressed plants in middle of frame (being attacked by the Galerucella beetle) and the
bright-colored plants behind -- in the cue to be consumed/killed

Bidens, or beggersticks, can be a bit of a nuisance when wearing fleece or neoprene (seeds stick to everything) --
but the ducks happily feed on them come fall, so we welcome their presence in the natural succession plan

Roy estimates he saw as many as 1,000 shorebirds (big numbers but not huge diversity) earlier this week;
rain in today's forecast might make Friday's viewing worth breaking out the field guide and camera -- to be continued

I could go on and on cataloging the plants we are seeing now and the various outcomes that could evolve. But as Roy keeps saying, "This is a one week at a time proposition." We watch the weather, watch the response, and adapt accordingly.

Some Unexpected Management Partners

Small but mighty: Galerucella beetle perched on an unsuspecting purple loosestrife leaf. Photo by A. Rusch

As much as I love a good cliffhanger, before moving on to introduce the next major thug (Phragmites) in what I’m recognizing is becoming a lineup of criminal invasive species, I think it’s worth telling the rest of the purple loosestrife story. While the battle for real estate in Lake Erie coastal marshes (and wetlands all over the state and region) was definitively being won by PL, new recruits to take on the fight were being investigated.

Traditional management methods (e.g. water level manipulation, mowing, disking, spraying) proved to have little lasting impact to curb the sea of purple. Ironically, the solution – or at least a meaningful step toward it – again came in the form of some tiny beetles from far-away lands. And unlike the borer that indiscriminately killed all the ash trees (see 3/21/17), these tiny insects were intentionally introduced as a carefully scripted form of “biocontrol.”

While studies were being conducted throughout the U.S. (and abroad), the Division of Wildlife was the group most actively engaged in introducing Galerucella beetles to Ohio. The long-time owner of a neighboring private marsh was distraught at the seismic shift in habitat he was witnessing and as such was willing to be a guinea pig. Beetles were first introduced into the broader Bay View marsh complex in the early to mid-1990s as one of the first test sites in the state. The results have been astounding. There are plenty of examples of biocontrol efforts gone bad (think Frankenstein fish), but this was a case where the beetles took hold, ate what they were supposed to eat when they were supposed to eat it, and left everything else pretty much alone. As PL numbers decline, so do beetle numbers.

This has been the case now for more than two decades. Loosestrife still exists on the marsh, but the populations are isolated and the beetles are lying in wait to rise up and consume anything that gets too out of control. (As an aside that we can talk about later, the resulting “seed bed” – viable seeds residing in underlying sediment – from all those years of rampant proliferation by PL give the beetles plenty of job security.)

Purple loosestrife went from an epidemic that many assumed would just become the new normal, to a manageable irritant. Unfortunately for area marshes, just as PL started its precipitous decline, a new monster was rapidly gaining a foothold . . .

(I told you that I loved cliffhangers!)


Dig deeper:

Invasive Plants of Ohio Fact Sheet
Biological Control of Purple Loosestrife