In It for the Long Haul

Niwot Ridge LTER Site. Image Credit: Jeff Taylor

With the oldest of our stations having been installed in 2012, the iRON is a relatively young network. Our vision, though, is to collect data not just for a few years, but for decades and generations to come. While this vision is perhaps ambitious, it draws upon the inspiration and experience provided by examples of successful long term monitoring efforts.

Perhaps one of the most famous legacies of long term monitoring is that of Charles David Keeling, whose perseverance in recording and maintaining careful records of Carbon dioxide concentrations at Mauna Loa, Hawaii played a critical role in identifying human influence on atmospheric greenhouse gas concentrations and the climate.

Tundra at Niwot Ridge LTER. Image Credit: Jeff Taylor

At a network wide scale, the largest, longest-lived monitoring effort in the US is the Long Term Ecological Research Network (LTER). LTER began in 1980 with funding from the National Science Foundation, but some of its individual sites have been established far longer. Harvard Forest, for example has been collecting data since 1907 as a research and education location. LTER currently has 26 official research sites. They are located across the U.S., with a few special sites present in the Caribbean and Antarctica. This broad reach allows for sharing and coordination across a diversity of ecosystem types from the arctic tundra to coral reefs and from prairies to tundra.

These diverse stations are unified by three key characteristics: research must occur within areas that have been specifically identified as representative ecosystem types, it must focus on phenomena that occur on long time scales, and it must have cross-site applications. Collecting consistent data over extended durations of time is critical to understanding the natural world because ecosystem processes occur on different temporal scales. Some insects may live as adults for only a few days before mating and dying and be influenced by habitat conditions over a very short period of time. Forests, by contrast, are characterized by species that may live hundreds of years and cycles of disturbance and regeneration that take even longer to fully manifest their impacts. Long term research networks, therefore, are crucial to identifying trends that occur on scales that may be longer than a typical researchers' career or that may have repercussions within our lifetimes.

At Niwot Ridge LTER in Colorado, for example, the data collected are being applied to furthering understanding in a variety of fields that directly impacts people's daily lives, such as: water dynamics or identifying warning signs of harmful levels of air pollution.

Because ecological monitoring reveals trends over time, it can sometimes be challenging at the outset to estimate in exactly what ways the data will be most valuable. As we establish our own, local monitoring network in the iRON, we will consider local interests and information needs, as well as build upon research from other areas to identify potentially valuable areas of investigation. The iRON may be in its early days still, but every monitoring network has to start sometime, and with the context of a rapidly changing climate as a background, starting now offers an abundant opportunity to start understanding what those changes mean for our own valley.

Neighbors in the Field

One of my favorite aspects of fieldwork happens to be the same component that makes ecological research so challenging: you are not working in a controlled environment. This means that you never know what--or whom you may run across on any given day.

Yesterday, my colleagues and I conducted a soil collection at a location designated for a new addition to our monitoring network. The purpose of this soil collection is to calibrate the instruments we will use in relation to the exact soil type at the site. Because soil type and texture influence how tightly water is held in the soil, readings by the same instruments can vary slightly depending on where in the ground the readings are taken. Calibrating the equipment to soil from your exact location helps to account for those differences when you later analyze the data.
Once the calibration is complete, the soil is returned to its original hole. It is especially important to return the samples to the hole in the correct order if soil type varied by depth. At one location where we collected soil yesterday, soil became progressively more sandy as we dug down, and the difference between the dark, soft soil near the surface and the light, sandy soil at 20 inches (50 cm) was quite striking!

During our soil collection we did not see much wildlife, but evidence of one particular neighbor in the field was quite evident, as we walked to and from our sites. Black bears (Usus americanus) are quite common in the Roaring Fork Valley, and we were not surprised that many of the aspens in the study area were marked with numerous gouges from bears, some of whom had clearly been climbing the trees. What did give us pause, however, was how very new many of the markings were--so new in places, that the raised wood was still light in color and splintery.  Additionally, we found multiple piles of fresh bear scat in a range of sizes. (It seems that service berries are good eating up there.) These clues that we may be working in an area favored by the large, furry locals offered an important reminder to remain alert at this, and other, sites.

We'll be back to these new site locations in a few weeks to install the climate and soil moisture stations, and we'll be sure to share any special signs or sightings of our neighbors.

On the Learning Trail

The Viewline Trail. Credit: AGCI

This time of year is a beautiful season for field work. We have been visiting our monitoring stations for their spring check-ups and updates, and we've been generating all kinds of questions about the natural world along the way!

Visting the Brush Creek station at the end of June, one of the first things I noticed was a small gang of ground squirrels basking in the dust of the pull-off from the road. I had suspected all winter that voles were the ones eating our wires, but it looks like there may have been competition in the rodent destruction department. So far, the new piping we buried in the spring has kept rodent visitors of all species out, though, and we're keeping our fingers crossed that this prevention method will continue to be successful.

Evening Primrose. Credit: AGCI

Coming down from the Sky Mountain station the following week, we spotted a mammal of a different kind. At the junction between the Ridgeline and Viewline trails, an ermine, also known as a short tailed weasel, paused to cast a glance our way. This ermine was sporting its summer color--a dusty tan.

Summer colors were in no shortage that day. The wildflowers were in vibrant bloom, and along the purple lupine edged trail, we stopped to take photos of some other wildflowers that neither of us recognized by name. One of our favorite discoveries was a white flower we later found to be evening primrose (Oenothera casepitosa). The distinctive nature of this white flower made it easy to identify in a search: its large petals were notably heart-shaped. Even more remarkable, however, was the manner in which the flower altered over the course of the day. In the morning, when we hiked up the trail, the flowers looked fresh and in full bloom, but by mid-day, when we hiked down, the flowers looked wilted and crumpled.

Tent caterpillar. Credit: AGCI

Even at the monitoring site itself we found a few moments to spare for curiosity. A furry caterpillar with a bright blue back and a row of white spots found its way on to a wrench. Research revealed it to be a forest tent caterpillar--and a potential threat to aspen trees. We delved further in our inquiry and asked the folks at Aspen Center for Environmental Studies about tent caterpillars. They reassured us that these insects are generally a threat to host plants only if other severe stressors already exist.

These types of learning experiences are one of the best parts of field work, in my opinion. They also help to inform the research we are conducting in an indirect way. The primary purpose of our monitoring sites is to shed light on the dynamics of soil moisture in a changing climate. In ecology, however, each component of the system interacts with the other components around it. The soil moisture helps determine which plants can grow in an area, and these plants in turn dictate the likely fauna of the region. The biotic and the abiotic factors of any ecosystem are intricately intertwined. As a consequence, keeping a weather eye open for changes in timing and presence of a natural event or species can prove helpful in creating a broad understanding of the ecosystem being studied. There is an even subtler benefit to this type of inquiry as well though. Curiosity is the driving force behind science, and by taking the time to ask questions and peer at flowers, two researchers at least are feeding the wonder that keeps them working in this field.

Muddy Waters Don't Always Mean the Blues

Meeting of Frying Pan and Roaring Fork Rivers after a heavy rain. Image Credit: John K., 2015

Rivers running red may sound ominous, but in the Roaring Fork Watershed it is a common spring phenomena. Heavy (or persistent) rains wash the red, iron-rich soil from steep areas of the slopes surrounding the Frying Pan into the swift-flowing waters of the river. This sediment laden water is carried downstream to Basalt where it joins the also high-flowing Roaring Fork River, creating a striking visual at the confluence.

That there has been a lot of erosion in the last few days is no surprise. Over the last week, all of our soil moisture stations showed over .95 inches of rain, with the Brush Creek station (near Snowmass Village) and Glassier Ranch station (near Basalt) showing as much as 1.39 inches in a single week. Between .8 and .9 inches of that rain fell in just 24 hours. To put that in scale, the Roaring Fork Valley receives only 16-19 inches  of precipitation on average per year. Last year, the most rain falling in a single 24 hour period was around .8 inches. Last year, such deluges did not occur until late summer.

In the arid state of Colorado, a good soaking is generally considered a good thing. What this heavy rain in early May means for water availability during the rest of the growing season is, like the Frying Pan, unclear. The rate at which soil dries depends on a number of related factors including air temperature, humidity, and plant water use. Consequently, weather conditions over the coming months will play a big role in how long this moisture sticks around in the soil. 

So far, this week's rain has raised soil moisture by the notable amount of between 7 and 10% at our sites at a 2 inch depth. Soil moisture at the 8 and 20 inch depths has only risen by between 1 and 2% so far, but as water from the shallow depths has time to percolate, these numbers may rise further.

As we continue to move toward summer, collection of data from the research sites will help to illuminate the relationship between precipitation, temperature, and soil moisture. In the meantime, the vegetation shows its response to the rain by making the valley look especially verdant and bright.

Data from the Smuggler Mountain Site from 4/30/15-05/07/15. It is important to note that the scales of water moisture are not consistent across the three graphs. As a result, although all lines visually appear to rise by similar amounts, the 2in depth is actually showing a much greater increase numerically. Image Credit: AGCI, using Hobolink data collection and graphs.

The Trouble with Voles

Meadow Vole, side view. Image Credit: Japanese Tea, Wikimedia Commons

These wee, furry beasties are cute enough to look at. Voles belong to the order Rodentia and are similar in appearance to a short-tailed version of their relative the mouse. Some species, including the prairie vole, mate for life. With an average length of 5-6 inches, they are just about the right size to fit in the palm of an adult's hand--not that handling a wild rodent is ever recommended. Five different species of vole can be found in the Roaring Fork Valley alone (Huggins, 2004). They feed on seeds; grasses; forbs; fungi; and, apparently, wires.

Thus we come to the trouble with voles. They are not friends to long-term monitoring, at least not to the sensors that gather data. We suspected a threat might be crouching on the horizon last August when we noticed numerous holes dotting the ground during a siting visit for one our soil moisture and climate monitoring stations. During the installation of the site, suspicions were confirmed when I saw a small, brown shape shoot from one hole to another. It was a vole.  I did not get a clear enough view to say which of the Roaring Fork's five species graced our site with its presence, but I did see enough to know that rodent presence in the area might be a challenge to our data collection.

Right from installation, any exposed wire at the site was wrapped in reflective tape, a common method for deterring rodents. After the one sensor became damaged at the start of winter, I secured the remaining sensors in an additional 5 five layers of the aluminum tape.  The resulting bundle was as wide around as the pvc pipe used to protect the wires stretching from the tower to their monitoring location location. This measure was only sufficient until the end of winter. Last week, we made a repair visit to the site and found a pile of small rolls of aluminum tape  that had been plucked from the wires and flung about a 2-foot diameter radius in little, chewed-upon balls. In addition to removing the protective tape from the exposed section of wire, the voles had pulled a greater length of wire out of the PVC pipe to access further surfaces for chewing. The wires themselves had been completely chewed through. It was both distressing and impressive.

Science loves nothing like a challenge, however, and we were game for this one. Having preemptively armed ourselves with piping elbows, lengths of unused pipe, duct tape, and reflective tape, we removed the damaged soil sensors and replaced them with new equipment--now protected by an elaborate system of piping that descends underground to a depth of over 6 inches. 

By the end of the afternoon, storm clouds were beginning to scud in, bringing with them a biting wind. But before the rain and chill drove us out, we were able to burry new sensors (now successfully gathering data) and collect the damaged sensors for later repair. Previous splicing experience will soon be put to the test as we attempt to salvage our vole-ravaged wires.

Stringing the wires from the hole to the logger tower. Image Credit: AGCI, 2015

Sometimes research looks like a calm lab technician in a white coat surrounded by spotless beakers, sometimes it looks like someone intent on a computer screen running data through a newly designed modeling system, and sometimes it looks like a person lying on her stomach in the soil and spikey grass, taping wires with muddy fingers. All of these scenarios represent the earnest endeavor to better understand how this world works and the ways it may be changing over time. The one scenario we hope science does not look like any time soon is a charming little rodent with its mouth full of wire.

Reference:

Huggins, Jain Lindsey. 2004. Wild at Heart. WHO Press. Basalt, CO.

2015 Year of the Soil!

Soil profile at Brush Creek. Image Credit: AGCI, 2014

It's official, this year is the year to dig your hands into the dirt!

The Food and Agriculture Organization (FAO) of the United Nations has officially declared 2015 the "International Year of Soils." The humble earth beneath our feet is receiving this recognition for a variety of reasons. Soil is the foundation of all plant life on Earth (literally!) from the foods we eat, to the flowers we admire, or the forests that become timber to build tools or homes.

Soil plays a critical role in non-living systems as well. It filters and stores ground water, it interacts with the atmosphere and it can play a role in the warming (or cooling) of microclimates.

While all soils serve a similar purpose within their ecosystems, soil is incredibly diverse. Soil comes in a variety of colors, textures, and chemical compositions. Different soils also have their own individual arrays of bacteria.

Here within the Roaring Fork Valley, some of this diversity is evident even from a distance. Traveling from Glenwood Springs to Aspen, the soil undergoes a visible change from the bright red, iron-rich soil near Glenwood to the more muted brown tones of the soil up near Aspen.

These soils differ on a less-visible level as well.  Among the four study sites that currently comprise the Roaring Fork Soil Moisture Network, there are clear differences in soil texture and composition.

At Smuggler Mountain, the soil is a slightly acidic, loose loam (a mix of sand, silt, and clay) with less than 1% organic matter. It's low in nitrogen, but high in phosphorus.

At Sky Mountain, by contrast, the soil is also a loam, but it is less acidic and more densely packed. The organic matter is much higher--around 11%, and it has more nitrogen available than phosphorus.

The Brush Creek site, a meadow, is very different from the two forested sites. It's classified as clay and is nearer to neutral pH than the other two sites. Its organic matter content is around 7% and its nitrogen and phosphorus availability are close to one another.

Glassier, which is something of a wetland in the summer, is a sandy loam, and near the surface, it is near neutral for pH and has a high phosphorus availability and 33% organic matter.

The differences in the soils is both driven by and drives the type of plants that live in these areas. For example, at Smuggler Mountain, the low nitrogen availability may limit what types of plants are able to establish and succeed in the area. Meanwhile, the fact that the dominant vegetation in the area are conifers likely contributes to the acidic nature of the soil. (Needles from conifers tend to lead to acidic soils when the decompose.)

Soil is an important determinant in the type of ecological communities you find, no matter where you go on Earth--and the relationship is reciprocal. So what does the soil like where you live? 2015 is the year to find out!

Digging in at Brush Creek. Image Credit: AGCI, 2014