Tag Archives: Soil

Over sixty years digging and we’re still finding new ‘dirt’ on HJ Andrews

One kilometer. Or roughly ten football fields. That’s the extent of the area over which Karla Jarecke, a Ph.D. candidate in the College of Forestry’s Department of Forest, Ecosystems & Society can feasibly navigate her way through the trail-less HJ Andrews Experimental forest to collect the data she needs in a typical day of field work. Imagining a football field is perhaps not the best way to appreciate this feat, nor envision the complex topography that makes up this coniferous forest on the western flanks of the Cascade mountains, roughly 50 miles East of Eugene. But these characteristics are precisely what have made this forest valuable to scientists since 1948 and continue to make it the ideal place for Karla’s research.

Experimental watersheds like the HJ Andrews forest were established initially to understand how clear-cutting influenced forest drainage and other ecosystem processes such as regrowth of plants and change in nutrients in soils and streams. This was during the time when timber-take was increasing and we still had little understanding of its ecosystem effects. Karla’s work is also forward-thinking, but less on the lines of what will happen to drainage when trees are removed and more focused on understanding the availability of water for trees to use now and in the future. She wants to know what influence topography has on plant water availability in mountainous landscapes.

Meter deep soil pits at Karla’s field site.

Back to bushwhacking. The answer to Karla’s research question lies beneath the uneven forest floor. Specifically, in the soil. Soil is the stuff made up of weathered rock, decomposing organic material and lots of life but it is also the medium through which much of the water within a forest drainage moves. Across her study area, Karla has 54 sites where she collects data from sensors that measure soil moisture at two different depths. These steel rods send electrical currents into the ground, which depending on how quickly they travel can tell her how much water is present in the soil. She also keeps track of sensors that measure atmospheric conditions, like temperature and air humidity. This information builds on the incredible sixty-year data set that has been collected on soil moisture within HJ Andrews, but with a new perspective.

Digging soil pits on steep slopes occasionally required stacking logs at the base of a tarp to prevent the soil from sliding down the hill.
Photo credit: Lina DiGregorio

Karla explains that there have been long-standing assumptions surrounding elevation gradients and their control on water availability in a forest system. This understanding has led to modeling tools currently used to extrapolate soil moisture across a landscape. But so far, her data show huge variability on surprisingly small scales that cannot be explained by gradient alone. This indicates that there are other controls on the spatial availability of soil moisture in such mountainous terrain.

“We’re finding that model doesn’t work really well in places where soil properties are complicated and topography is variable. And that’s just the first part of my research.”

The next phase of Karla’s work seeks to evaluate tree stress in the forest and determine if there are any connections between this and the variability she is finding in soil moisture across spatial scales. True to the complex nature of the landscape, this work is complicated! But to Karla, it’s important. Growing up in the mid-west, Karla came to know water as “green” and when she moved West, first to fulfill an internship in Colorado and then to pursue her graduate work here in the Pacific Northwest, she was (and still is) amazed by the abundance of clean, clear rivers and streams. And it’s something she doesn’t ever want to take for granted.

Karla and her sister Stephani snowshoeing on Tumalo Mountain in the Cascade Range of central Oregon.

To find out more about Karla’s research and her journey from farming in Italy to studying soil, tune in on Sunday, October 27th at 7 PM on KBVR 88.7 FM, live stream the show at http://www.orangemedianetwork.com/kbvr_fm/, or download our podcast on iTunes.

Karla’s episode on Apple Podcasts

Dirt: It’s under all of us!

We depend on the humble soil beneath our feet to grow the cotton in our shirts, feed the world with fruits and vegetables, and growing all the commodities necessary to make beer and whisky alike! Given the range of functions soils have on earth it’s no surprise soils themselves have very different colors, sizes, and even smells! If we look closely at soils, especially their horizons resembling layers of a cake, they can be read to ascertain how nutrients got there, how long those nutrients can last for the plants above, and what to do if an area needs to be remediated.

Great soil profile showing the burial of an old soil (reddish-grey) formed on a basalt flow. The soil surface was buried by volcanic ash ejected during the cataclysmic eruption of Mt.Mazama (Crater lake. Photo taken near Cougar Ridge, Eagle Cap Wilderness,Summer 2015.

Great soil profile showing the burial of an old soil (reddish-grey) formed on a basalt flow. The soil surface was buried by volcanic ash ejected during the cataclysmic eruption of Mt. Mazama which is now Crater lake. (Eagle Cap Wilderness, Summer 2015)

12cm is of soil is precariously protected from alpine winds by a thin gravel mulch (Summer 2015).

12cm is of soil is precariously protected from alpine winds by a thin gravel mulch (Summer 2015).

 

 

 

 

 

 

 

 

 

Even though humans rely on soils for our health and comfort, we too often take soil for granted. But our guest reminds us exactly how essential soils are to life! Vance Almquist is a PhD student joining us from the Crops and Soil Science Department, in the College of Agricultural Sciences, and focuses on how soils develop in wildland environments, as well as how to read soils in order to understand its historical record keeping. Vance is also known as a soil pedologist, or someone who studies soil genesis, its transformations, and specializes in how to read the language of soil horizons. You might ask, ‘why do we need to know the history of a soil in order to use it?’

Human society developed in the ‘Cradle of Civilization’, an area known as the Fertile Crescent because (as you guessed it) the soils were extraordinary fertile! To practice higher-level agriculture, early settlers built levees to block the floodwaters. But when they prevented the annual floods soils were no longer getting enough nutrients, salts started to build up, and eventually it lead to a collapse of civilizations. If only they understood the soils’ history, they would’ve know the annual floods are essential to maintaining their prosperous way of life. If we know how soils develop, and how to read them, these are the kinds of problems we can avoid in the future.

Hiking toward China Cap in the Eagle Cap Wilderness to describe and map soils (Summer 2016)

Hiking toward China Cap in the Eagle Cap Wilderness to describe and map soils (Summer 2016)

Vance grew up in Utah and before yearning to be a soil scientist he worked at a brewery, trained dogs, and is a master forklift driver. High school was never terribly fun because nothing really challenged him, but he continued to enroll in classes at the local community college. He was really turned onto botany because he always went mushroom hunting as a kid and he saw the practical application of knowing which plants we share the world with. Then he realized how soil science was at the intersection of biology, chemistry, and physics. Here he found his calling because he also noticed how much our economy was overlooking the usefulness of soils and wanted to continue to explore this idea further in graduate school.

Not only can understanding soils avert disasters, but ranges of scientific disciplines are dependent on soils. A botanist can be interested in finding rare flowers, a hydrologist is interested in finding out how much sediment is mucking up the streams, and a meteorologist wants to know how much CO2 is released into atmosphere. Specific soil properties are needed for certain plants to grow, some soils erode faster than others, and soils can become a source, instead of a sink, of CO2 emissions! Soils are integrators of many scientific disciplines and I hope you join us to discuss this with Vance. You can tune in on Sunday November 20th at 7PM on 88.7FM or listen live here.