16. Gentianopsis virgata.

 

2020-10-04

The Distribution of Snow Trillium.

If we look at distribution of Trillium nivale, what patterns do we see? Happen before I posted about distribution patterns in Ohio, but what about in other states?

Above is the county range map for snow trillium from the USDA website. You can see T. nivale is only in the Midwest US and in a small area in Appalachia. The state with the most counties is Illinois, but some states only have one or two counties. There are no snow trillum in east Iowa, or in central Wisconsin, or in most of Michigan (or east Ohio, but I wrote about that before). Also, there is that big bow across Illinois, the weird diagonal in Indiana, the two or three metapopulations in Appalachia, and some other patterns.

We know most times snow trillium lives on limestone or dolomite talus, so does this map and a map for potential karst (calciferous cave) overlap?

Wow. Okay, this seems not random! You can see how in Ohio snow trillium is only in karst regions. The only counties in Michigan are along the limestone part of the Michigan Shield. The diagonal counties in Indiana follows the edge of a karst region. There is no karst in central Wisconsin, so the snow trillium counties are along the edges. And the Appalachian populations are only in areas with limestone bedrock outcrops. We can see how the western extent is limited by moisture; and maybe we can guess that the south extent is limited by temperature. But what about the northern extent? And what about the bow across Illinois, and those counties in west Minnesota? And how did snow trillium come to the very disjunct area in central Michigan?

If we overlay the county records on the extent of the glacial maximums, we can see that most populations are close to the margin of the Wisconsinan glacial maximum. Happen they are not perfect, but you can really see how this is true in Indiana and Ohio. We can also see that there were possible refugia from glaciers in the whole Quarternary (2.5 million years) in Missouri, the driftless region of Wisconsin, southern Indiana, Adams County in Ohio, and all of the Appalachian metapopulation. Trillium seeds are ant dispersed so happen they move slowly. And if in most areas they are moving along river corridors where bedrock is exposed, as I think happen in Ohio, then happen they can only move where the glacial till is cut. If we compare this map with the above karst map, we can also see there is not really any limestone bedrock in northern Wisconsin and most of Minnesota. So happen the northern limit is maybe from no calciferous bedrock and the slow movement keeps them out from the Upper Peninsula yet.

These questions continue:

1. Why are there all the populations in central Illinois where there is no karst topography (and seem no limestone bedrock)?
2. Why are there populations in west Minnesota and Iowa where there is no karst?
3. How did the disjunct Michigan populations get to completely glaciated Michigan with no karst from Ohio to the shield and no populations in northwest Ohio?


First, Illinois. People describe their habitat as on river banks and bluffs. If we look at the bedrock of Illinois, we can see most that area in the center the state is Pennsylvanian shale and sandstone, and only in west part of the state we see Mississippian limestone in surface bedrock. So happen we can think all the counties in that west part the state, and in the north where there is karst potential, are bedrocks where snow trillium can live. But what about all those counties in the middle of Pennsylvanian shale and sandstone?

When we look at the map in the link, we think, okay, there is not a lot limestone in Illinois. But...if we look at the strata map:

We see, yes, those surface rocks are siltstone, shale, and sandstone, BUT, under that is many many MANY feet perfect limestone layers. How close the surface this limestone? Not really far; close enough the rivers can cut into it. If we map the counties with snow trillium against the close to surface limestone:

That is not random. And more, happen you can see you never see records down in the south, where the sandstone and shale layers are very deep. So, happen no karst, but more than enough limestone in river valleys.

Second, Minnesota and Iowa. For Iowa we can see most all the surface bedrock in the west part of the state is Cretaceous sandstone or shale. But, we can see from the larger river valleys in the Bedrock map that Mississippian and Pennsylvanian limestone are close the surface here. So happen we can guess these are also on river cut slopes and bluffs. And also these should include populations in Lincoln County, North Dakota around the Big Sioux River.

Minnesota is weird.

According to Minnesota Wildflowers, there are populations on limestone river slopes in the southeast part of the state, where you think you find snow trillium because there is karst potential there. But the biggest populations are not there, they are in the prairie regions. On alluvial floodplain soils.




What.

This is not normal for snow trillium. In Ohio we only see them on limestone and dolomite talus and gravel. In Pennsylvania and West Virginia they are on outcrops. In Indiana they are on limestone outcrops. In Illinois they are on limestone bluffs and river slopes. This pattern is most everywhere we see snow trillium, but in southwest Minnesota, in the Minnesota River Prairie, happen they are in floodplain forests. I don't know if this is a normal thing for them that happen they do less now less than they did long time ago, or happen this is adventive habitat. But, most of the Minnesota River Prairie soils are "gray calcareous till", maybe from Ordovician dolomite pushed from bedrock to the East? I really don't know. It is alkaline enough for the snow trillium.

The last question is, how snow trillium come to central Michigan? The counties where you find snow trillium here are in a ring around the Michigan Basin. You can see that limestone ring on the karst map above. But the most close populations to these are 170 miles to the south in Indiana, or similar distance across Lake Michigan in Wisconsin. The Michigan populations are in the Grand River valley, and the North Indiana populations are in the Wabash River valley, and there is a continental divide (but not high) between them. There are no glacial refugia in Michigan, it was all covered with ice 30 thousand years ago.

There are really only two possible things. First, maybe there was a corridor 20 thousand years ago when the glaciers were receding, and the snow trillium followed it North. With time the intermediate populations went away. Happen this is a vicariance explanation. Second, if there was no corridor, it must long distance dispersal. By what? Bird?

But I think we can say some things: Snow trillium is always close to rivers, most times on slopes or talus or bluffs, rarely in alluvial soils of floodplains, where they can grow if the soil is alkaline enough. And because most refugia are close to large rivers, the Ohio River, Mississippi, Missouri, it was not difficult for them to disperse along limestone and dolomite layers up river when the glaciers receeded. Because their populations are really scattered, it say to me they were more widespread before and many those intermediate populations extripated when the hydrology or soil changed, or they had too much shade under thick canopy. I think before, because snow trillium is very small and it bloom in cold weather and have short life cycle, maybe it is similar alpine plants, but I have no more information for tell me that.

Snow Trillium in Ohio

Trillium nivale on limestone talus slope in Southwest Ohio.

Snow trillium (Trillium nivale) is one our most early, most small, and most secret spring wildflowers in Ohio. It grows only on thin alkaline soil around rivers, most times in forests but sometimes around the Scioto River in open areas, and always it grows over Silurian limestone or dolomite bedrock or gravel.  The above picture not exaggerate the size, it is really that small when it blooms.

T. nivale distribution, from "Snow Trillium in Ohio", R.L. Stuckey, 1976.

If you look at the above map from Stuckey, 1976, you can see the distribution is wide and scattered in Southwest Ohio, but there are only two sites in the East part of the state, in Jefferson county. These are on isolated limestone outcrops, and these are close to other populations on outcrops in western Pennsylvania. Eastern Ohio has most sandstone and shale bedrock, so happen you will never see snow trillium in those areas. It is a very strong calcicole, it never crosses the shale/limestone boundary line on the map. In western Ohio, most bedrock is Silurian mix of limestone, dolomite, and some shale. But over these in most areas there is many feet glacial till, except in river valleys where water cut down through the till and expose the bedrock. I talk a little bit about this in my post about Chinquapin Oak.

Brassfield limestone cliffs on Little Miami River

Because the rivers cut through and expose the bedrock, for snow trillium they are corridors. Ants disperse the seeds through the limestone talus, and where there is not really a lot competition, the snow trillium make colonies. But there are two more important lines on the Ohio map. One line, through the southeast part of the state, is the glacial maximum. All areas above that line had glaciers sometime in the past 300 thousand years. This means Dayton and other areas in southwest Ohio were covered with hundreds feet ice and the land under destroyed. No wildflower can live there, so happen the snow trillium must move north from refugia after the glaciers left. The only areas with snow trillium and alkaline bedrock in the not-glaciated area are in Adams county. Chalet Nivale in Arc of Appalachia is a good example. In the paper with the above map, Stuckey thought that the snow trilium moved from refugia in Adams county north into the Miami and Little Miami and Scioto River valleys. And I think it seem right they move along river valleys where bedrock is exposed.

Cedarville Dolomite cliffs on Massie Creek Gorge

There is one more thing about the Ohio distribution map. You never really see snow trillium in talus around Cincinnati. The bedrock there (in black) is Ordovician, not Silurian. And many the bedrock is limestone [Stuckey says it is dolomite, but the strata profile below show limestone, so happen I don't know why he think that]. Snow trillium prefer limestone, but it will also grow on dolomite soils. Example is Massie Creek Gorge, and the dolomite there is name for the town (Cedarville Dolomite). But you will never find it in Caesar Creek Gorge. Why? Stuckey not guess in that paper, and it is really weird you never find it around Cincinnati.

From "Geology of the Dayton Region in Core and Outcrop", G.A. Schumacher and more, 2012.

If you look at the Silurian limestone and dolomite layers in the above strata map for the Dayton area, you can see that shale layers surround them, but they are still really defined layers. Both the Cedarville Dolomite and the Brassfield Limestone are thick and separate from the shale layers. But if you look at the Ordovician layers around Cincinnati, you can see most limestone/dolomite is mixed with shale, or it is thin layers between shale layers. Shale rock is acidic, and snow trillium will not grow on it. And when shale break apart it become a gray acidic clay, and most times you can think this will cover and cancel the alkaline buffer from the dolomite. Maybe the pH is high enough for mild cacicoles, example Jeffersonia, but it is not alkaline enough for snow trillium.

Waynesville Formation? Ordovician dolomite and shale in Caesar Creek Gorge

 So happen I think this happen. When the glaciers receded, the snow trillium followed the river valleys north into central and southwest Ohio, where Silurian limestone and dolomite was exposed. First this was most the southwest part of Ohio, but over thousands years the rivers cut down through the Silurian layers into the mixed Ordovician shale-dolomite. And with more time the Ordovician valleys widened and the Silurian layers were only on the boundaries. Populations around Cincinnati shifted north and west and east on the boundary and the old populations extirpated because the soil it was not alkaline enough. Now you only see them on and north from the Ordovician boundary.

T. nivale after a little March snow.

Chinquapin oak forest and limestone.

I bought this book recently, finally. I wanted it for a long time. It is a book with lists of all the vascular plants in John Bryan State Park, Glen Helen Nature Preserve, and Clifton Gorge State Nature Preserve. All three are on Limestone gorges on the Little Miami River in Greene County, Ohio.

I wanted this book because I am thinking more now about limestone edaphic plant communities. There are many this kind around me, calcareous prairie-fens, limestone and dolomite gorges, old quarries, and limestone talus slopes.

The picture above is part from a bedrock map of Ohio. The black box is center on Greene county. You can see. most the bedrock in the county is Silurian dolomite (Green and Gray) with Silurian limestone under (Tan). The bedrock under the Silurian layer is a mixed Ordovician dolomite-shale (Purple). In most areas the bedrock is not exposed, because there are many feet of Wisconsonian age sediment and soil over the top. But rivers cut down through both the glacial terrain and the bedrock, so happen around rivers many times the bedrock is exposed. This is what happens in Clifton Gorge, Massie Creek gorge in Cedarville, and around other streams and rivers in the area. Many times when the soil is deep the bedrock under will push the groundwater up through calcareous gravel and make marl flats on the surface. This is where you can find fens. But this post it is really not about low areas but about the ridges and more dry areas one kind tree I many times find there, Chinquapin Oak (Quercus muhlenbergii).

Bark from large old Chinquapin Oak in Clifton Gorge.

In Clifton Gorge and other limestone ridges in Greene County, the most common large canopy tree is chinquapin oak. Sture Anliot, the author of the Clifton Gorge plant list book, wrote that he thought these chinquapin oak dominant forests were an intermediate forest type between Oak-Hickory forests you can see all around the Dayton area here and East, and Beech-Sugar Maple forests you can see more in far West Ohio. Or maybe they were a kind of Oak-Sugar Maple forest everywhere in Southwest Ohio.

Pink=Oak-Hickory and Thickets; Yellow=Prairie; Orange=Oak-Sugar Maple; Green=Beech-Sugar Maple; Purple=Ash-cottonwood swamp

The map above shows four forest types for the original vegetation in Greene County. For the Oak-Hickory forest, a close good example site is the woods around the fen in Gallagher Fen State Nature Preserve in south Clark County. For Beech-Maple forest, Davey Woods State Nature Preserve in Champaign County or Hueston Woods State Nature Preserve in Preble County are the best examples in Southwest Ohio. For Red Oak-Sugar Maple forest, I really like the Wright State University Woods.

Chinquapin Oak Leaf

When I see chinquapin oak in these habitats, most times I see the leaves first and then happen I realize they come from the biggest tree trunks second. The dead leaves are really distinct in these areas because they are the only leaf with wave tooth margins. The other trees are mixed but most times I see sugar maples and other oaks. There are chinquapin oaks in Clifton Gorge, in John Bryan, and in Glen Helen, but they are also in the Wright State University Woods on ridges, and on the Brassfield Limestone remnant at Oakes Quarry in Fairborn. They are probably in Indian Mound Reserve, but I not yet look for them there.

The weird thing about these really big trees is happen, they not really grow best in these kind dry closed forests. They like open areas, savannahs, prairies, where they can grow and grow and grow with no competition.  It is the same habitat where happen you can see Bur Oak (Quercus macrocarpus). We see these big oaks on limestone ridges and slopes many times, in Ohio, Kentucky, Tennessee, and other states. But also happen we never really see seedlings or young trees. This is because Chinquapin Oak is not shade tolerant. It only really grows in disturbed areas. When the canopy opens it grows really fast and when it matures it lives a really long time. When the understory is shaded there are no more new trees until the next big disturbance, maybe a windstorm or a fire. So happen, they are not really climax species in this habitat, and this is not really a special forest type, it is Oak-Sugar Maple or Mixed Oak forest with co-dominant Chinquapin Oak. And maybe in 100 years if the canopy is stable enough happen all the Chinquapin Oaks they will die from old age and these habitats will be only other oaks and Sugar Maple. When I compare other species in these habitats, I find they are really normal Oak-Maple forests with maybe some calcium loving elements.

People not really learn this until after Anliot wrote his book. I think it is interesting how if we look at ecosystems in only one time we can judge them wrong, we can think a relic from more early disturbance is a climax species. And it really is common tree for see on these ridges and slopes in Greene County, so happen maybe it is still important in the right times.

14: Moneses uniflora.

2020-01-08

13: Symplocarpus foetidus

2020-01-06