7.12.26

Turning up the heat

Tall goldenrod plants flowering in one of the ambient condition plots.

As you step into a warm greenhouse, you can feel how the glass has captured the sun’s heat inside. Now imagine that same warmth spreading across the entire planet due to increased greenhouse gas emissions. Climate scientists predict that by the year 2100, Earth’s average temperature could increase by as much as 3°C because of climate change. That might sound small, but even a few degrees matter a lot.

At the Kellogg Biological Station in southwest Michigan, a group of researchers wanted to know how climate warming will affect plant communities. To find out, they created what they call “mini time machines” using open-top chambers. These chambers are clear, hexagonal-shaped structures that trap heat and make the air inside warmer – just like a greenhouse. The chambers still allow for natural levels of precipitation, air flow, and insects to enter through their open tops. By comparing plant communities grown in these warmed conditionswith chambers, to ambient conditions without the chambers, scientists can see how rising temperatures might impact the plants in the future. Understanding these changes can help us prepare for a future where the climate is different from what we know today.

A scientist collecting data outside an open-top chamber.

The scientists working in the open-top chambers were at multiple stages in their careers. Moriah is a graduate student who became fascinated with plants when she first learned how to identify different species. Instead of looking at plants as all one patch of green, she could then notice all the diversity and the different roles they play in an ecosystem. Mark is a lab technician working with Moriah. He is interested in how plants will respond to warmer climates because it gives a glimpse of the world his grandchildren will see.

When Moriah and Mark started, they were joined by a few other scientists: Kara, another graduate student, and Emily, an undergraduate student. The open-top chambers had already been out in the field for five years. The field was growing with a diverse mix of plants common in the area. Together, they observed that plants growing in the warmed conditions inside the chambers seemed to be taller than those growing in the ambient conditions outside the chambers.

To collect some data to back up their observation, the team began with one species, tall goldenrod. This is a wildflower species with a bright yellow flower, and it is one of the most common species at this location. They wanted to see how goldenrod growth differed in warmed and ambient conditions. When temperatures rise, some plants grow faster and taller to compete for sunlight, but this takes a lot of energy. That means plants have less energy for survival, making seeds, or defending against herbivores, like insects. The researchers predicted that goldenrod inside the chambers would be taller, but would also have fewer stems and plants because they were putting their energy into growing tall instead of making more plants.

Open-topped chambers at the Kellogg Biological Station.

To test their ideas, the team measured goldenrod height with meter sticks and counted the number of goldenrod stems in each plot, called abundance. Their experiment had 30 plots. Half of the plots had open-top chambers, and half did not. That gave them 15 replicates of each treatment. Each plot is 1 meter x 1 meter. 

Featured Scientists: Mark Hammond (he/him), Moriah Young (she/hers), Kara Dobson (she/hers), and Emily Parker (she/hers) from the Kellogg Biological Station Long Term Ecological Research Program

Flesch–Kincaid Reading Grade Level = 9.3

Additional Resources:

  • The group of researchers featured in this activity work together at the Kellogg Biological Station, part of Michigan State University. Their lab is called the Spatial and Community Ecology Lab (SpaCE Lab). To learn more about their lab and work, students can visit their website or check out the Scientist Profiles associated with this activity.
  • Trevor Grabill produced a woodblock printed piece featuring the open-topped chamber experiment, titled What if it’s beautiful?. Along with the piece, they also produced a Zine that includes testimonials by the artist and scientists.
7.12.26

Missing species: the biodiversity of prairie remnants

The scientist team visiting a prairie remnant field site.

Illinois is called the “Prairie State.” Historically, 60% of the state was covered in different types of prairies, or open grassy landscapes with few trees. As far as the eye could see, fields were filled with colorful wildflowers, grasses, and all the species above and below ground that rely on them. However, today only 0.01% of the prairies remain across the whole state! These undisturbed areas are known as remnant prairies, and despite their small size, they are still home to a diverse community.

What happened to the rest of the prairies? Most were converted by people into agricultural fields to grow crops for food. The soils below prairies are rich in nutrients, and the agricultural lands in Illinois today provide food consumed by millions.

Researchers identifying plants in the field to document species richness. 

Nick is a land manager whose passion is prairies. In addition to protecting and studying remnant prairies, he creates restored prairies by planting prairie plants back into agricultural areas where they were historically found. However, Nick and other land managers are finding something surprising – the restored prairies do not look like the remnant prairies. He noticed that some of the native plants come back and thrive in the restored prairies, while others do not. 

To investigate these missing species, Nick partnered with a local scientist, Mike. Mike grew up in rural Michigan and has always been fascinated with biodiversity. He is passionate about bringing back missing species, because he knows even just one missing plant can have a cascading effect through an ecosystem. For example, wild lupine plants are a key food source for the endangered Karner blue butterfly. When prairie restorations have higher diversity, we’re more likely to benefit other species.  

Nick and Mike want to figure out why some species re-establish and others do not. They thought the key might lie belowground. From Mike’s past research, he knew that many prairie plants species form beneficial relationships with microbes belowground, called mutualisms. Could the root of the problem be explained by what is happening below ground? If these mutualist partners are missing in the soil, some plant species may not be able to survive.

One mutualist in prairies is called arbuscular mycorrhizal fungi, or AMF. Plants supply these fungi with sugars from photosynthesis. AMF help plant roots gather nutrients and water from the soil. AMF are common in prairie soils, but are often missing from soil that has been used for agriculture. Agriculture removes AMF in several ways. Tractors till the soil, disturbing the fungi below ground. Chemicals may be sprayed to kill harmful microbes, but these chemicals can also kill beneficial fungi, like AMF.

Nick chose an experimental site that was historically a sandy prairie, but had been used as a farm more recently. He used AMF originating from local remnant sand prairies to add to the experimental plots. Nick used a seed spreader to launch the AMF along the base of the plants. He set up three treatments that differed in how much AMF was applied: 1) a low level of AMF, 2) a high level of AMF, and 3) a control where no AMF was added. This setup was repeated 5 times in experimental blocks, or similar rectangular plots. 

After the growing season, Mike and his lab identified the plant species in each block. To help out, Jeremy joined Mike’s lab after finishing graduate school. He was a good fit because he had been working with similar data. Jeremy used the full dataset to calculate species richness, or the number of different plant species in each block. 

Featured Scientists: Mike Grillo and Jeremy Davis from Loyola University-Chicago and Nick Budde from the Forest Preserve District of Will County, Illinois. Written with Kerrie Rovito and Katarina Alvarado from Chicago Public Schools. Funding from the Walder Foundation.

Flesch–Kincaid Reading Grade Level = 8.8

Additional Teacher Resources:

If you would like to show students a remnant prairie that is close to where the scientists collected their data, you can see a video here.

You can see a video of Kankakee Sands, the area where the data were collected, here.

Videos about mycorrhizal fungi:

12.11.24

Little butterflies on the prairie

Butterfly on prairie flower.
A Tiger Swallowtail butterfly visiting a prairie flower to drink nectar.

The activities are as follows:

Butterflies are insects with colorful wings. You will often see them in a field, flying from flower to flower. Butterflies eat a sugary food made by flowers, called nectar. In return, the butterflies help the plants make seeds by moving pollen. As they travel from flower to flower, pollen is dropped off. This helps plants reproduce and make seeds. This is called pollination, and butterflies are pollinators. We need pollinators to grow many of the fruits and vegetables that we eat!

Prairies are habitats filled with many types of flowers. The Midwestern United States used to be covered in prairies. Today, most have been replaced by farm fields. Crops like corn and soybeans are commonly planted in the Midwest. Farm fields are important because we need land to grow our food. But this also means there is less food and habitat for butterflies.

Many farmers are concerned with growing our food while still protecting habitat for butterflies and other species. They want to know – how can we grow food for ourselves while still growing flowers for butterflies? A group of scientists in Michigan is working with farmers to think of solutions. The team is made of people from many different backgrounds and work experiences. The members of the team change over time, but typically 8 scientists are working together at a time. They all come together to brainstorm and do their research at the Kellogg Biological Station in Michigan.

Group of researchers ready to go out into field to butterfly survey.
Members of the Haddad Lab, ready to go out for a day of butterfly sampling in the prairie strips!

Prairie strips are a new idea that might help both farmers and the environment. These strips are small areas of prairie that can be added to farm fields. They look like rows of flowers and grasses within a field. They create habitat for many species, like butterflies, birds, ants, and even microscopic fungi and bacteria! Prairie strips may also help our food grow better by providing habitat for pollinators.

To figure out if prairie strips are able to draw in butterflies, the research team needed to collect data. They visited a large experiment that had many different kinds of farm fields. Some of the fields had prairie strips, while others did not. They thought prairie strips would help butterflies by adding habitat for them in farm fields that usually don’t have many flowers. They predicted they would see more butterflies in fields that have prairie strips and fewer in fields without these strips.

To count the butterflies in each type of field, the team went out on sunny spring and summer mornings when butterflies were flying around and eating nectar. They walked along the same paths in the same fields at the same time every week. Each time, they counted all the butterflies they saw within 5 meters. Each walk was 12 minutes long and followed a 150-meter path. They did these counts in 6 farm fields without prairie strips and 6 farm fields with prairie strips. The team counted butterflies like this 20 times over the summer. At the end of the summer, they added up all of the butterflies observed in each field. This number is called butterfly abundance.

Featured scientists: The Haddad Lab from Kellogg Biological Station Long Term Ecological Research Program – KBS LTER

Flesch–Kincaid Reading Grade Level = 7.3

11.17.23

The prairie burns with desire

Stuart showing an Echinacea flower setting seed.

The activities are as follows:

Fire plays a crucial role for prairie habitats across North America. Native Americans have long observed that lush and green pastures grow after a wildfire. In many areas, it is part of current and historical native culture to imitate this natural process by deliberately burning the prairie in a controlled way. This land management practice has many benefits, such as helping native grasses form seeds, thinning out plants, and enhancing habitat for prairie animals. By using controlled fires to cultivate these areas, Native Americans increase the availability of food and connect to the environment and their cultural traditions.

Some land management agencies plan prescribed burns to increase the health of prairie ecosystems. However, fire is still suppressed in many North American prairies due to the possible damage to human development. In these areas, scientists have observed that fire suppression contributes to local plant species extinctions, but we do not know why.

Stuart is a scientist interested in how fire can help prairie plants. In the late 1990s, Stuart was in central Minnesota searching for prairie plants in the Echinacea genus. The prairie was ablaze with flowers, so he had no difficulty finding plenty of plants. He tagged each plant so that he could study them again in the future. However, when he returned the following year, the field had almost no flowers! He kept returning to this same field. A few years later he found the site was again filled with flowers. That year there had been a prairie fire. Visually seeing the impacts of fire on the landscape is a memory he will not forget.

Stuart became interested in learning more about how fire affects the reproduction of native prairie plants. He knew that Echinacea plants grow in many places, but they have a hard time making seeds. This genus cannot self-pollinate, meaning they must be fertilized with pollen from a genetically different plant. Echinacea plants are also dependent on insects, such as bees, to pollinate them.

Echinacea flower

In 1996, a research team started collecting data on Echinacea plants in a large research site in Minnesota. This prairie site had a schedule for prescribed burns, or controlled fires that are started by experts to manage the land. These burns would happen every 4-6 years during the spring.

The team established a set of plot locations that they visited each summer. They searched for and mapped the location of all flowering Echinacea plants within these plots. They took measurements on each Echinacea plant – whether it was flowering, and the distance to its second closest Echinacea neighbor.

Stuart decided to take a new look at this long-term dataset. He had two ideas for how fire might be helping Echinacea plants. First, fire might help all the plants get on the same schedule and make flowers at the same time. This synchrony, or flowering at the same time, could help pollen get from one flower to another. Second, fire might remove competing plants from the area, opening up bare ground for new seeds to establish. This would allow Echinacea plants to be closer to one another, again making it easier for pollen to move between flowers.

With these data, Stuart could compare years with and without prescribed burns to see whether fire helped Echinacea flowering. To look at whether fire decreased the space between blooming Echinacea plants, he looked at the distance between a focal plant and its second-closest neighbor. To see whether fire increased the synchrony of flowering, Stuart used the data to calculate the proportion of Echinacea plants that were in bloom during the summer sampling period.

Featured scientist: Stuart Wagenius from the Chicago Botanic Gardens Written by: Harrison Aakre

Flesch–Kincaid Reading Grade Level = 8.6

Additional teacher resources related to this Data Nugget:

More information about the Echinacea project, based in Minnesota. There are additional datasets to explore, blog posts from the field, identification guides, and pictures of the experiments.

Article to learn about cultural perspectives that are traditionally not represented in textbooks. Native Americans have, and continue to incorporate ecology, observations, and making sense of patterns for millennia.

For more information about indigenous knowledges, or traditional ecological knowledge, check out the following websites:

Published journal article about this research. Wagenius, S. et al. 2020. Fire synchronizes flowering and boosts reproduction in a widespread but declining prairie species. Proceedings of the National Academy of Sciences.

11.14.22

Does more rain make healthy bison babies?

A bison mom and her calf.
A bison mom and her calf.

The activities are as follows:

The North American Bison is an important species for the prairie ecosystem. They are a keystone species, which means their presence in the ecosystem affects many other species around them. For example, they roll on the ground, creating wallows. Those wallows can fill up with water and create a mini marsh ecosystem, complete with aquatic plants and animals. They also eat certain kinds of food – especially prairie grasses. What bison don’t eat are wildflowers, so where bison graze there will be more flowers present than in the areas avoided by bison. This affects many insects, especially the pollinators that are attracted to the prairie wildflowers that are abundant in in the bison area. 

Not only do bison affect their environment, but they are also affected by it. Because bison eat grass, they often move around because the tastiest meals might be scattered in different areas of the prairie. Also, as bison graze down the grass in one area they will leave it in search of a new place to find food. The amount of food available is largely dependent upon the amount of rain the area has received. The prairie ecosystem is a large complex puzzle with rain and bison being the main factors affecting life there. 

The Konza Prairie Biological Station in central Kansas has a herd of 300 bison. Scientists study how the bison affect the prairie, and how the prairie affects the bison. Jeff started at Konza as a student, and today he is the bison herd manager. As herd manager, if is Jeff’s duty to track the health of the herd, as well as the prairie. 

One of the main environmental factors that affect the prairie’s health is rainfall. The more rain that falls, the more plants that grow on the prairie. This also means that in wetter years there is more food for bison to eat. Heavier bison survive winters better, and then may have more energy saved up to have babies in the following spring. Jeff wanted to know if a wet summer would actually lead to healthier bison babies, called calves, the following year.

Jeff and other scientists collect data on the bison herd every year, including the bison calves. Every October, all the bison in the Konza Prairie herd are rounded up and weighed. Since most of the bison calves are born in April or May, they are about 6 months old by the time are weighed. The older and the healthier the calf is, the more it weighs. Very young calves, including those born late in the year, may be small and light, and because of this they may have a difficult time surviving the winter. 

Jeff also collects data on how much rain and snow, called precipitation, the prairie receives every year. Precipitation is measured daily at the biological station and then averaged for each year. Precipitation is important because it plays a direct role in how well the plants grow. 

Jeff and a herd of bison on the Konza prairie.
Jeff and a herd of bison on the Konza prairie.
Konza LTER logo

Featured scientist: Jeff Taylor from the Konza Prairie Biological Station

Written by: Jill Haukos, Seton Bachle, and Jen Spearie

Flesch–Kincaid Reading Grade Level = 8.7

Additional teacher resources related to this Data Nugget include:

  • The full dataset for bison herd data is available online! The purpose of this study is to monitor long-term changes in individual animal weight. The datasets include an annual summary of the bison herd structure, end-of-season weights of individual animals, and maternal parentage of individual bison. The data in this activity came from the bison weight dataset (CBH012).
  • For more information on calf weight, check out the LTER Book Series book, The Autumn Calf, by Jill Haukos.
1.8.21

Fertilizer and fire change microbes in prairie soil

Christine collecting samples from the experimental plots to measure root growth.
Christine collecting samples from the experimental plots to measure root growth.

The activities are as follows:

Stepping out into a prairie feels like looking at a sea of grass, with the horizon evoking a sense of eternity. Grasses and other prairie plants provide important benefits, such as creating habitat for many unique plants, mammals, insects, and microbes. They also help keep our water clean by using nutrients from the soil to grow. When plants take up these nutrients, they prevent them from going into streams. High levels of plant growth also keeps carbon bound up in the bodies of plants instead of in the atmosphere.  

Prairies grow where three environmental conditions come together – a variable climate, frequent fires, and large herbivores roaming the landscape. However, prairies are experiencing many changes. For example, people now work to prevent fires, which allows forest species to establish and eventually take over the prairie. In addition, a lot of land previously covered in prairie is now being used for agriculture. When land is used for agriculture, farmers add nutrients through fertilizer. With all these changes, prairie ecosystems have been declining globally. Scientists are concerned that as they disappear so will the benefits they provide. 

Lydia and Christine are two scientists contributing to the effort to learn more about how to preserve prairies. They both became interested in studying soil because of their appreciation for prairies at a young age. For Lydia, she lived in an area that was covered by trees and farmland, but knew at one time it used to be prairie. This made her want to learn more about prairie environments and how places like where she grew up have changed through history. For Christine, she grew up surrounded by prairies where she developed a passion and curiosity for the natural world. Especially for the organisms living in the soil that you cannot see, called microbes. 

These are two different experimental plots within the large field experiment at Konza Prairie Biological Station. The one with lots of trees is an unburned plot, the one with lots of grass is a burned plot.
These are two different experimental plots within the large field experiment at Konza Prairie Biological Station. The one with lots of trees is an unburned plot, the one with lots of grass is a burned plot.

Lydia and Christine read about how grassland scientists have been doing research to learn more about what happens when fire is stopped and excess nutrients are added. These changes reduce biodiversity and affect which species of plants can grow in the prairie. However, Lydia and Christine noticed that the research had been mostly focused on what happens aboveground.  Lydia and Christine had a hunch that the aboveground communities were not the only things changing. They thought that belowground components would be changed by fire and fertilizer too. They turned their focus to microbes in the soil, because they also use nutrients. In addition, they thought these microorganism would be affected by the changes in aboveground plant biodiversity. 

To see if this was true, they used data that they and other scientists collected at Konza Prairie Biological Station from a large field experiment. The experiment was set up in 1986 and the treatments were applied at the field site every year until 2017! Lydia and Christine focused on the fertilizer (nitrogen) addition and prescribed burning treatments to answer their questions. The nitrogen treatment had eight plots where nitrogen had been added and eight with no nitrogen as a control. Similarly, the prescribed burn treatment was applied to eight plots, while eight plots had no burning as a control. These two treatments were also crossed with each other, meaning that some plots were burned and nitrogen was added.

Lydia and Christine expected the types of microbes in the soil to change in response to the nitrogen and burning treatments because of the different aboveground plant communities and difference in soil nutrients. Soil microbial communities can change in multiple ways. First, the number of unique species can increase or decrease, measured as richness. The other way is how many individuals of each species there are in the community, measured as evenness. Taken together, richness and evenness give a measure of diversity, which can be summarized using the Shannon-Wiener index. The value will get bigger if either richness or evenness increases because it incorporates both. For example, a community with five species that has equal abundance of each will have a larger Shannon-Wiener index than a community with five species where one species has a lot more individuals than the other four.  

Featured Scientists: Lydia Zeglin and Christine Carson from the Konza Prairie Biological Station. Written By: Jaide Allenbrand

Flesch–Kincaid Reading Grade Level = 10.4