As a 6-year-old living enthusiastically in the Jurassic and Cretaceous, fascinated by images of brontosaurs bigger than my house and tyrannosaurs that could terrorize my teachers, I would have been shocked and dismayed to discover what was going to survive and prosper over the next 100 million years.

It would have been difficult to imagine that in a world famous for its impressive and highly evolved dental work — tyrannosaurs with fearsome, foot-long choppers and plant-eating sauropods with teeth that grew so fast they were replaced every month – the only dinosaurs that would make the transition to the present were the toothless ones, the relatively unimpressive beaked dinosaurs whose descendants today are pecking away at the trees in my yard.

How could anyone with reasonable expectations predict that the descendants of the heavily armored and elephant-sized ankylosaurus would go extinct in a matter of a few years, while the modest ancestor of our soft-shelled turtles would survive to the present?

Or that in Cretaceous forests dominated by towering ancestors of Japanese plum yews and monkey puzzle trees, the future of forests would depend on delicate plants floating in steamy swamps – water lily- and coontail-like herbs that would become the ancestors of oaks, walnuts, hickories, beech, birch, magnolias, ash, chestnut and most of the world’s other tree species.

Or – most amazing of all –  that a few tiny, shrew-like and possum-like creatures, as insignificant as gnats to the mighty dinosaurs, would become the foundation for the age of mammals that followed, and the ancestors of the modern era’s most influential placental mammal.

It all changed, rapidly, at the end of the Cretaceous, about 70 million years ago. It was all showing signs of change even before a curve ball from deep in the galaxy blasted a hole more than 100 miles wide and 12 miles deep on the edge of the Gulf of Mexico. The impact and resulting earthquakes created tsunamis estimated to be more than 300 feet high. Super-heated rock melted most of the world’s forests. Aerosol, dust and particle clouds likely led to deadly extremes of heat and cold and allowed only flickers of sunlight for years. 

Lineages near the top of their game died off instantaneously. Many of the rest collapsed in the years that followed. Others, like the cone-bearing forests, lost even more ground to the upstart forests of flowering trees, many of which had come out of the long nights of the polar circles and were better adapted to the difficult and dark conditions that followed. 

It wasn’t just the immediate impacts of the meteor that led to extinctions. Because so much of life was wiped out, the rules of the game changed. Surviving species that were able to quickly capitalize on the world that remained out-competed and drove to extinction the surviving species that didn’t get there first. With the sudden loss of all the world’s major plant eaters, forests spread and thickened, likely eliminating plants that used to prosper in the sunlit planes and glades left by the footprints and appetites of dinosaurs. Seventy-five percent of the life on earth went extinct. It was likely ten million years before that diversity of species recovered.

We don’t need another meteor. That kind of massive upheaval in species and ecosystems is happening again, driven not only by rapidly changing climate, but by the explosive expansion and consumption of the planet’s heaviest and most burdensome species. Even before we see the most intense impacts of climate change, the rate of extinctions is clearly proceeding orders of magnitude faster than species can be replaced, thousands of times faster than the normal rate. And I feel as clueless as my 6-year-old self, so impressed and fascinated with the giants of our lifetime that I can’t imagine what the forest of the next century will look like.

Nor can any of us. And that’s why every species in the forests of Paint Rock and Alabama and the South has to be treated as if the future depended on it. Not all of it will survive, even in the best of circumstances. And we can’t easily predict which species will survive. But maintaining that biodiversity – even the species we don’t seem to depend on now — represents our choices and our hope for the future.

And not just those things we decide to call species. Because it’s increasingly obvious that the foundation for life after the great Cretaceous extinction was determined by individuals, or pairs of individuals, or small groups of individuals that managed to be in the right place at the right time. More often than not, they likely had unusual genetics – different from the rest of their kind —  that allowed them to survive the loss of the very conditions their ancestors had evolved to take advantage of. 

We chose to do our research here because Paint Rock seems to have a long history of ensuring that species and genes are in the right place at the right time. As climate changed and wiped out virtually all species in much of North America repeatedly over the past several million years, places like Paint Rock repeatedly helped repopulate the rest of the country with species and genes lost elsewhere. That can happen again.

But we don’t want to leave the future solely to the accidents of disaster. We believe we have a unique role to play here at the Research Center, helping to identify the genes most likely to survive into the future. And we believe we have a responsibility to make sure they get there.

Bill Finch PaintRock.org

Be careful what you pick up on the banks of the Paint Rock River. There’s a frighteningly real risk it may be the last of its kind.

Carla Atkinson, the aquatic biologist and ecologist from University of Alabama, reminded us of this when she toured the Paint Rock River recently. One of the river’s brief rages had subsided, and we combed the beach looking for what had been left behind. Carla is a mussel specialist — a good thing to be in a state that has more mussel diversity than the entire South American continent — but even she was a little taken aback when she laid the spent shells out and counted the number of mussel species in this small stretch of stream.

It’s not a large river by Alabama standards. The main stem is 60 miles long, one of the state’s smallest. The drainage basin, with all its tributary streams stretching up above the Walls of Jericho into Tennessee, is only a little bigger.

 But for some reason, it remains packed with life. The riverine unit it’s part of is rivaled only by the Cahaba and upper Alabama as a center of aquatic diversity for all of North America. A half mile of stream in either of those places would have more fish species than the entire state of California. Paint Rock’s diversity may have once been rivaled by the much larger Tennessee tributaries downstream — the Elk, the Flint, the Duck. But careless development and water management have long since compromised the diversity of those rivers. And thus the Paint Rock stands alone, as the last refuge of one of the world’s most biologically diverse environments.

I was startled the other day to realize how large an area that last refuge serves. I spent many years along the Swannanoa River in North Carolina, outside Asheville, which is connected to the Tennessee by way of the French Broad. A hundred and fifty years ago, the Swannanoa must have looked something like the Paint Rock. But the valley floor of that river is now so packed with warehouses and retirement homes and highways and strip malls and parking lots and folks looking to grab a scenic view of nature, there’s no room left for a river to run. And the Swannanoa, like so many American rivers, is rapidly becoming little more than a ditch.

So as I was parsing the life stories of the many rare species in the Paint Rock, just below the preserve, I was surprised to find how many were first identified hundreds of miles away, on the other side of the Appalachians. The very elegant and critically imperiled blotched logperch, for example, was first identified in the Swannanoa River, very near a spot I once used to fish (with little success). And while the blotched legperch may have once been widespread in the Tennessee system, it is now completely gone from the French Broad and most of its tributaries, including the Swannanoa. Only a couple of dozen populations remain anywhere. The healthy populations in Paint Rock will be critical to the survival of the species.

The same can be said of the once widespread palezone shiner. There are only two (2!) populations of this fish left globally, with the largest population in Paint Rock. And the Alabama lampmussel, which was lost from 95% of its original range, with only two (2!) remnant natural populations. And the pale lillput mussel, once known from many populations in three states, now reduced to one (1!) remnant natural population. Or the many other fish and mussels that are now rare or lost virtually everywhere but in the Paint Rock system. Many states are now looking to Paint Rock to restore their lost populations, and perhaps one day, there’ll be enough of the Swannanoa left to restore with blotched logperch from Paint Rock. 

Forests have rivers, and rivers make the forests surrounding them. That’s why it’s inevitable that the Paint Rock Forest Research Center will have to support research on the great river in the center of it all. Carla has been developing research projects in the Paint Rock River for some time, and brought with her Felipe Rossetti de Paula, a post doc researcher from Brazil who has been focused on how surrounding forests affect the course and health of rivers. We spent the better part of the day with Alabama A&M faculty and staff on this brainstorming tour, to see how Paint Rock could have the research it deserves.  Given the diversity we see, it ought to be one of the two or three most thoroughly researched rivers in North America.

A map showing vegetation zones of eastern North America at the end of the last glaciation. Look closely, and you’ll notice that sea level has dropped, allowing forests to extend about 80 miles south into the Gulf of Mexico. But up around the border of what is now Tennessee and Alabama, you’ll see the old frontline of North America’s deciduous forest.

I hope you appreciate how contrary Alabama’s climate is. We’re the wettest state in the country. Our springs start months earlier and our falls continue months later than springs and falls in most of the United States. And our humidity …well…

But what’s more important to our work here in Paint Rock, and what’s becoming increasingly important to all of North America, is that Alabama’s climate (along with neighboring areas in Georgia, northwest Florida, southern Tennessee and Mississippi) has always been exceptionally contrary, for hundreds of thousands and perhaps millions of years, through changing climate, multiple ice ages and glacial bulldozers. The last of those glacial explosions was actually surprisingly recent – about 50 to 75 forests ago, 18,000 years before the present. The Wisconsin glacial event, as it’s called, snuffed out almost all life north of Washington, D.C. Forests didn’t start over from scratch after those glaciers retreated. Some place – somewhere contrary and much, much warmer – had to be preserving those forests and sharing them with the rest of the country when the glaciers retreated.

What’s clearly made a difference in Alabama’s climate over hundreds of thousands of years is that churning ball of warmth, the Gulf of Mexico. Because big bodies of water lose and gain heat much more slowly than land or air, they tend to stabilize climate. And the Gulf/Caribbean ocean is a massive flywheel, collecting heat from the equatorial regions and spinning it up through the subtropics to the continental U.S.

It now produces so much heat, it exports a great deal of it via the Gulf Stream, which keeps England, Scotland and Ireland from becoming the Arctic countries they are adjacent to. But as the last ice age was at its peak, there’s evidence that the circulation of the Gulf Stream was cut short, so that the difference in temperature then between the coasts of Maryland and Georgia was greater than the difference in temperature between Maine and Georgia now.

And all that extra heat that didn’t escape? It likely stoked the relatively balmy conditions in the southernmost U.S., even as glaciers were crushing the world north of Maryland.

Understanding what that forest south of the glaciers was like, and determining what exactly was where, isn’t easy. There’s no controversy about forests in New England, Pennsylvania, Indiana, Illinois, Wisconsin, Michigan, most of Ohio: They simply didn’t exist. Under the glaciers, there was nothing but dirt, ground up rocks, and perhaps some hardy bacteria.

But imagining the forests south of the glaciers is much harder. The first and still the most important attempt to document the history of early southeastern forests was undertaken by the Delcourts – who reconstructed the forest history of North America by looking carefully at fossil pollen at multiple sites, including Goshen Springs in south Alabama, and Anderson Pond and Mingo Pond just above Paint Rock in Tennessee.

Don’t try to imagine forests that look exactly like the ones we have now. The much higher carbon dioxide levels of the past few hundred years makes it easier for leaves to freeze, for example. CO₂ levels were less than half what they are now at the height of the last glaciation, which may help explain why trees we now consider freeze sensitive appeared to live side by side with trees we now know only from very cold areas. (And yes, it’s reasonable to wonder what happens to cold tolerance in plants as CO₂ levels continue to rise – something that’s going to be increasingly important as changes in climate produce less predictable spring and fall frosts, as is happening this year throughout eastern North America.)

What’s increasingly clear, however, is that the world immediately south of those glaciers was very different than what we see now. The higher areas of the Appalachians were comparable to Alaskan tundra, and the lower Appalachians were boreal forest like you’d expect to find in northern Canada. And this, I should remind you again, was only about 50 forests ago.

Research by the Delcourts, and those who’ve followed, indicate that the there was a fairly distinct transition zone between those arctic conditions in the central Appalachians and the warmer forests stretching from about Birmingham and continuing about 80 miles south of Mobile Bay, as the growing glaciers dropped sea level dramatically.

The colder part of that transition zone was in central Tennessee, and appeared to be a strange mixture of deciduous forest trees and spruce and fir forests. But as Hazel Delcourt notes:

Full-glacial refuges for deciduous forest species may have also existed in south-facing gorges of the Cumberland Plateau and southern Appalachian Mountains in addition to bluffs along major streams in the southeastern United States.

If you’re wondering what a south-facing gorge on the edge of the Cumberlands and the Appalachians might look like, three prominent examples come to mind: Tallulah Gorge in Georgia, Little River Canyon in Dekalb County, and Paint Rock Valley.

Interestingly, the Delcourts and others also point out the potential importance of “sinkholes” as refuges for species during the last ice age. These sinkholes not only buffered the local temperature extremes. They also would have been important moisture refuges during multiple extended dry periods, from the peak of glaciation to the present. If you think sinkholes are insignificant, let me introduce you to Callaway Sinks, our two-mile wide and beautifully forested sinkhole that seems to be a refuge within a refuge.

So it’s no surprise that the pollen evidence from middle Tennessee suggests that the first post-glaciation forests resembled the moist forests of Paint Rock now, with ash, butternut, ironwood, moisture-loving hickories. The abundance of elm pollen, for example, provides still more evidence that the Tennessee/Alabama border seems to be the cradle of elm diversity in North America. A few of those elms developed special genetic characteristics that helped them survive extreme cold and follow the retreating glaciers northward. But many more species stayed behind in the Southern Cumberlands – the beautiful September elm that was once a signature tree of Birmingham and Huntsville; the newly discovered American elm population that is likely the disease-resistant ancestor of the disease-susceptible elms that went up north; the genetically distinct butternut that survives in spite of the fact that butternut has been lost almost everywhere else in North America. It’s as if they were waiting for a warmer world to spread their much richer genetic heritage.

You may have noticed, that warmer world is here, and getting warmer by the year. That’s why we’re here, and it’s why we’re here, in northeast Alabama, on what has been the frontline of forest survival over millions of years of climate changes.

Bill Finch  Paintrock.org