Tuesday, August 16, 2022

Ecology of Dakota Landscapes, a book review

Twenty five years ago, Carter Johnson and Dennis Knight were fishing together in eastern South Dakota, where both were born and raised. Both were professors of ecology—Johnson at South Dakota State University, Knight at the University of Wyoming. Between catching fish, they asked themselves why there was no book about the natural history of their beloved Dakotas. They decided to write one, but they had to wait until both were retired to finish it (1). In June 2022, the book was published by Yale University Press (2, 3).

As the authors state in their first sentence, Ecology of Dakota Landscapes was written "to share our enthusiasm for the natural history of North Dakota and South Dakota ..." But this also is a book about destruction and hope. The Dakotas exemplify the conflict between our love of nature and our survival needs—food in this case. Will we find a way to sustain both agriculture and our natural heritage? In their final sentence, the authors leave us wondering about the future: "The challenges are great, time seems short, the ongoing quest to make a sustainable living continues."

Dakota Landscapes begins with a three-chapter introduction to geography, ecosystems, geologic and human history, and climate (including a discussion of climate change). North and South Dakota are part of the Northern Great Plains, where summers are hot and often dry, and winters can be very cold. The Missouri River crosses the two states from northwest to southeast, separating areas with very different geologic histories. North and east of the river, glaciers repeatedly advanced from the north until just 10,000 years ago; landscapes are young, with flat to undulating terrain. In contrast, ice sheets rarely extended south and west of the river. Instead some sixty million years of deposition and erosion have created rolling plains dotted with buttes, badlands, and canyons. Far to the west, at the South Dakota/Wyoming state line, are the Black Hills—a striking outlier of the Rocky Mountains.

Glacial extent during the Pleistocene is a major determinant of distribution of landscapes and ecosystems in the Dakotas. Based on Johnson & Knight 2022; and Bluemle 2016, North Dakota's Geological Legacy.
Just 150 years ago, the Dakotas were largely covered in native grass. With the exception of the forested Black Hills, trees were sparse—limited to ravines, stream and lake margins, and scattered uplands. The mighty Missouri flowed unimpeded through 800 miles of riparian woodlands. But European settlement brought dramatic change; the Dakotas now support a mix of native and human-created ecosystems.

After the introductory chapters, the book is organized by ecosystems, both native and human-created. Grasslands, which occupy the greatest area (40%), come first. Evolution has made Dakota grasslands naturally resilient. Grasses will grow new leaves in response to grazing, and their rigid cell walls reduce wilting. The majority of grassland biomass—as much as 80%—lies below the surface, where "every cubic yard of soil has miles of plant roots and fungal filaments (hyphae) that sustain millions of bacteria and thousands of invertebrates". Death and decay underground are major contributors to soil fertility. The majority of prairie grasses are perennial and have shallow underground buds, allowing regeneration after surface disturbance.

Photo by Dehaan, modified. From the Land Institute, used on many websites (source of height).

The most extensive native grasslands in the Dakotas are the mixed-grass prairies of the drier west. They have long been grazed, originally by bison, now mostly by cattle. When properly-managed, grazing removes surface matter without damaging the ecosystem. In contrast, most of the tallgrass prairies of the wetter eastern Dakotas have been damaged beyond recovery, victims of conversion to cropland. This sad tale begins the next chapter, "Agriculture and Agroecology".

The glaciers that advanced across the eastern Dakotas created ideal farmland, and when settlers arrived in the late 19th century, they found millions of acres of rich soil. But it was covered in thick grasses as much as six feet tall. So before planting crops, they broke and removed the sod, including all the vital underground biomass. The consequences—soil erosion, sedimentation of streams and wetlands, and decline in water quality—contributed to the Dust Bowl of the 1930s. Though agricultural practices improved in response, the land never fully recovered. Now fertilizers, insecticides, and herbicides are needed where native grasses once thrived on their own.

Another gift of glaciation is the Prairie Pothole Region (PPR), which extends south from Canada through much the northern Great Plains, including the eastern Dakotas. When the ice sheets vanished, they left behind thick deposits of glacial debris containing huge chunks of ice. These melted to form tens of thousands of water-filled depressions—a system of lakes and wetlands known as the "nursery of North American Ducks" (or simply "the duck factory").

Prairie Potholes, North Dakota. USFWS photo.
There also are chapters on deciduous forests, which are biologically important far beyond their limited extent; ponderosa pine forests and woodlands, with a lengthy section on the Black Hills; planted shelterbelts (windbreaks), which have greatly increased tree cover in the Dakotas; buttes, badlands, and sandhills; and rivers and riparian ecosystems. The mighty Missouri rightly gets its own chapter.

The book's subtitle is Past, Present, and Future. That last word is the challenging subject of the final chapter, "Working toward Sustainability". Dare we hope to preserve native ecosystems and achieve sustainable agriculture? And in the face of climate change? The answer is ... maybe. Native ecosystems remain a large and important part of Dakota landscapes, and appreciation for them has grown. Agricultural practices have improved dramatically since the Dust Bowl; now there are encouraging examples of restorative agriculture and promising new methods to try. But change at the scale needed won't happen unless everyone contributes—that includes consumers (us!) as well as producers.

Ecology of Dakota Landscapes is both rigorous (e.g., sources are cited with endnotes) and readable. It will appeal to a wide audience, including outdoor enthusiasts, landowners, conservation biologists, policy makers, teachers, and students. The text is greatly enhanced by an exceptional collection of 200+ color photos and maps, with substantive captions.

Because of the immense range and amount of information, this is not a book to read once, cover to cover. And some readers may find the occasional science-dense sections off-putting, but these can be skipped with no harm done. Perhaps begin by perusing the many wonderful images and maps—it will be a solid introduction, and a fine way to plan your next Dakota outing.

Sand Lake Wetland Management District on the Missouri Coteau, South Dakota. USFWS photo.

Deciduous forest surrounds a wetland on Turtle Mountain in far north North Dakota. Photo by Ken Lund.


(1) To learn more about the book from the authors themselves, watch their recent book launch event on YouTube.

(2) The full citation is: Johnson, W. Carter, and Knight, Dennis H. 2022. Ecology of Dakota Landscapes; Past, Present, and Future. Yale University Press; Biodiversity Institute, U. Wyoming. ISBN 978-0-300-25381-8. Available in print and ebook format.

(3) Ecology of Dakota Landscapes was printed in China. It arrived in the US in March 2022 aboard the container ship Ever Forward, which went aground in Chesapeake Bay. It would take five weeks, two barges, and five tugboats to dislodge it, but only during a spring high tide and after removing 500 of the 5000 containers. Photo courtesy US Coastguard via Flickr (cropped).

Friday, August 5, 2022

August Tree Following—good news & a mystery

Balsam poplars c. 0.5 mi west of the Happy Jack Trailhead, Laramie Mountains.

Last month I didn't post a tree following report because when I got home from my travels and checked my tree, I realized ... I had chosen a dead tree! It had no leaves at all, in July. I looked around for another balsam poplar, but all I found were young saplings. What to do? Choose another kind of tree? I couldn't decide.

Several weeks later, on one of my regular summer hiking trails in the same general area, I was stopped in my tracks by ... a grove of balsam poplars! (photo above). Why had I never noticed them? Populus balsamifera is an uncommon species here, an outlier from its main range to the north. My only excuse is that the trail was a bit rocky and I had to watch my feet. However, the stand continued for some distance, to where the trail was smooth.

Leafy healthy trees.
Balsam poplar leaves are broadly lance-shaped, dark green above, noticeably paler beneath.
Suckers were coming up along the trail. How could I have missed these earlier?! Lost in thought I guess. Leaves on suckers were generally larger and greener.

Further along the trail was an excellent view of the grove, from the west. It includes several tree species, but they don't seem to mix within the stand, maybe because aspen are clonal, and balsam poplars can spread by suckering.

Note balsam poplar suckers invading the meadow.
The white feature in the meadow above may be an old well box. The inside has been taken over by willowherbs and buttercups, indicating the soil is wet. And it is surrounded by moisture-loving sedges (genus Carex). The quartz on the rim is local—a nice touch.

The challenge was to choose a tree to follow, one I would recognize on future visits. Most were roughly the same size, and grew fairly close together.

See what I mean? How to choose?
Two more poplars, with a stand of quaking aspen behind.
I soon found one obviously bigger than the rest, and I presume older. This is my tree. It is not dead. There are leaves in the canopy and on branchlets sprouting from the trunk.
Stout and gnarled.
A benefit of tree following is that we look closely at our chosen trees, noticing things that would be overlooked otherwise. That was the case here. Looking up the trunk, I spotted limbs that had been sawn off some time ago, including some high on the tree, way out of reach for sawyers on the ground.
This cut branch is twenty feet off the ground (measured with hand-span technology).
How did this happen? More than a few people will say the branches were cut when they were closer to the ground, back when the tree was younger and shorter. This stems (ha ha) from the common idea that trees grow taller from their base. But they don't. Lengthening occurs at the top and the tips of branches, at specialized apical meristems (same with roots). A branch that is twenty feet off the ground today was twenty feet off the ground when it formed (as well as when it was cut). Tree branches do not rise as a tree grows taller (see Will a Tree’s Branches Rise as It Grows?). So the mystery of the cut branches remains ... what do you think?

Now I'm back in business, happily following a tree. I highly recommend it—interesting, easy, no commitment. More information here.