1.15.19

Hold on for your life! Part I

Anolis scriptus, the Turks and Caicos anole, on Pine Cay.

The activities are as follows:

On the Caribbean islands of Turks and Caicos, there lives a small brown anole lizard named Anolis scriptus. The populations on two small islands, called Pine Cay and Water Cay, have been studied by researchers from Harvard University and the Paris Natural History Museum for many years. In 2017, Colin, one of the scientists, went to these islands to set up a long-term study on the effect of rats on anoles and other lizards on the islands. Unbeknownst to him, though, a storm was brewing to the south of the islands, and it was about to change the entire trajectory of his research.

While he was collecting data, Hurricane Irma was developing into a massive category 5 hurricane. Eventually it became clear that it would travel straight over these small islands. Colin knew that this might be the last time he would see the two small populations of lizards ever again because they could get wiped out in the storm. It dawned on him that this might be a serendipitous moment. After the storm, he could evaluate whether lizards could possibly survive a severe hurricane. He was also interested in whether certain traits could increase survival. Colin and his colleagues measured the lizards and vowed to come back after the hurricane to see if they were still there. They measured both male and female lizards and recorded trait values including their body size, femur length, and the toepad area on their forelimbs and hindlimbs.

Colin was not sure whether the lizards would survive. If they did, Colin formed two alternative hypotheses about what he might see. First, he thought lizards that survived would just be a random subset of the population and simply those that got lucky and survived by chance. Alternatively, he thought that survival might not be random, and some lizards might be better suited to hanging on for their lives in high winds. There might be traits that help lizards survive hurricanes, called adaptations. He made predictions off this second hypothesis and expected that survivors would be those individuals with large adhesive pads on their fingers and toes and extra-long legs – both traits that would help them grab tight to a branch and make it through the storm. This would mean the hurricanes could be agents of natural selection.

Not only did Hurricane Irma ravage the islands that year, but weeks later Hurricane Maria also paid a visit. Upon his return to Pine Cay and Water Cay after the hurricanes, Colin was shocked to see there were still anoles on the islands! He took the measurements a second time. He then compared his two datasets from before and after the hurricanes to see if the average trait values changed.

Featured scientist: Colin Donihue from Harvard University

Written with: Bob Kuhn and Elizabeth Schultheis

Flesch–Kincaid Reading Grade Level = 9.9

Additional teacher resources related to this Data Nugget:

  • This study was published in the journal Nature in 2018. Colin would like to thank his coauthors Anthony Herrel, Anne-Claire Fabre, Anthony Geneva, Ambika Kamath, Jason Kolbe, Tom Schoener, and Jonathan Losos. You can read the paper here.
  • Colin wrote a blog post about his experience. He shares more about the lead-up to the project and how a chance occurrence changed the entire trajectory of his research.
  • Colin also put together a story map with more images and animated gifs of this research.
  • We put together a PowerPoint of images from Colin’s research that you can show in class to accompany the activity.

To engage students in this activity, show the following video in class. This video gives some information on the experiment and Colin’s research. For Part I stop the video at minute 1:30.

1.7.19

All washed up? The effect of floods on cutthroat trout

The activities are as follows:

Mack Creek, a healthy stream located within the old growth forests in Oregon. It has a diversity of habitats because of various rocks and logs. This creates diverse habitats for juvenile and adult trout.

Streams are tough places to live. Fish living in streams have to survive droughts, floods, debris flows, falling trees, and cold and warm temperatures. In Oregon, cutthroat trout make streams their home. Cutthroat trout are sensitive to disturbances in the stream, such as pollution and sediment. This means that when trout are present it is a good sign that the stream is healthy.

Floods are very common disturbances in streams. During floods, water in the stream flows very fast. This extra movement picks up sediment from the bottom of the stream and suspends it in the water. When sediment is floating in the water it makes it harder for fish to see and breathe, limiting how much food they can find. Floods may also affect fish reproduction. If floods happen right after fish breed and eggs hatch, young fish that cannot swim strongly may not survive. Although floods can be dangerous for fish, they are also very important for creating new habitat. Floods expand the stream, making it wider and adding more space. Moving water also adds large boulders, small rocks, and logs into the stream. These items add to the different types of habitat available. 

A cutthroat trout. It is momentarily unhappy, because it is not in its natural, cold Pacific Northwest stream habitat.

Ivan and Stan are two scientists who are interested in whether floods have a large impact on the survival of young cutthroat trout. They were worried because cutthroat trout reproduce during the spring, towards the end of the winter flood season. During this time juvenile trout,less than one year old, are not good swimmers. The fast water from floods makes it harder for them to survive. After a year, juvenile trout become mature adults.These two age groups live in different habitats. Adult trout live in pools near the center of streams. Juvenile trout prefer habitats at the edges of streams that have things like rocks and logs where they can hide from predators. Also, water at the edges moves more slowly, making it easier to swim. In addition, by staying near the stream edge they can avoid getting eaten by the adults in stream pools.

Ivan and Stan work at the H.J. Andrews Long Term Ecological Research site. They wanted to know what happens to cutthroat trout after winter floods. Major floods occur every 35-50 years, meaning that Ivan and Stan would need a lot of data. Fortunately for their research they were able to find what they needed since scientists have been collecting data at the site since 1987!

To study how floods affect trout populations, Ivan and Stan used data from Mack Creek, one of the streams within their site. They decided to look at the population size of both juvenile and adult trout since they occupy such different parts of the stream. For each year of data they had, Ivan and Stan compared the juvenile and adult trout population data, measured as the number of trout, with stream discharge, or a measure of how fast water is flowing in the stream. Stream discharge is higher after flooding events. Stream discharge data for Mack Creek is collected during the winter when floods are most likely to occur. Fish population size is measured during the following summer each year. Since flooding can make life difficult for trout, they expected trout populations to decrease after major flooding events.

Featured scientists: Ivan Arismendi and Stan Gregory from Oregon State University. Written by: Leilagh Boyle.

Flesch–Kincaid Reading Grade Level = 7.5

Additional teacher resource related to this Data Nugget:

11.12.18

Can biochar improve crop yields?

Buckets of pine wood biochar.

The activities are as follows:

If you walk through the lush Amazon rainforest, the huge trees may be the first thing you see. But, did you know there are wonderful things to explore on the forest floor? In special places of the Amazon, there exist incredible dark soils called “Terra Preta”. These soils are rich in nutrients that help plants grow. The main source of nutrients and dark color is from charcoal added by humans. Hundreds of years ago the indigenous people added their cooking waste, including ash from fire pits, into the ground to help their food crops grow. Today, scientists and farmers are trying out this same ancient method. When this charcoal is added to soil to help plants grow, we call it biochar.

Biochar is a pretty unique material. It is created by a special process that is similar to burning materials in a fire place, but without oxygen. Biochar can be made from many different materials. Most biochar has lots of tiny spaces, or pores, that cause it to act like a hard sponge when it is in the soil. Due to these pores, the biochar can hold more water than the soil can by itself. Along with that extra water, it also can hold nutrients. Biochar has been shown to increase crop yield in tropical places like the Amazon.

Farmers in western Colorado wanted to know what would happen if they added biochar to fields near them. Their farms experience a very different climate that is cooler and drier than the Amazon. In these drier environments, farmers are concerned about the amount of water in the soil, especially during droughts. Farmers had so many questions about how biochar works in soils that scientists at Colorado State University decided to help. One scientist, Erika, was curious if biochar could really help farms in dry Colorado. Erika thought that biochar could increase crop yield by providing pores that would hold more water in the soil that crop plants can use to grow.

Matt, a soil scientist, applying biochar to the field in a treatment plot.

To test the effects of biochar in dry agricultural environments, Erika set up an experiment at the Colorado State University Agricultural Research and Development Center. She set up plots with three different soil conditions: biochar added, manure added, and a control. She chose to include a manure treatment because it is what farmers in Colorado were currently adding to their soil when they farmed. For each treatment she had 4 replicate plots, for a total of 12 plots. She added biochar or manure to a field at the same rate (30 Megagrams/ ha or 13 tons/acre). She didn’t add anything to control plots. Erika then planted corn seeds into all 12 plots.

Erika also wanted to know if the effects of biochar would be different when water was limited compared to when it was plentiful. She set up another experimental treatment with two different irrigation levels: fullirrigationandlimitedirrigation. The full irrigation plots were watered whenever the plants needed it. The limited irrigation plots were not watered for the whole month of July, giving crops a drought period during the growing season. Erika predicted that the plots with biochar would have more water in the soil. She also thought that corn yields would be higher with biochar than in the manure and control plots. She predicted these patterns would be true under both the full and limited irrigation treatments. However, she thought that the biochar would be most beneficial when crops were given less water in the limited irrigation treatments.

To measure the water in the soil, Erika took soil samples three times: a few weeks after planting (June), the middle of the growing season (July), and just before corn harvest (September). She weighedout 10 gofmoistsoil, thendried the samples for24 hoursin an oven and weighed them again. By putting the soil in the oven, the water evaporates out and leaves just the dry soil. Sarah divided the weight of the water lost by the weight of the dry soil to calculate the percent soil moisture. At the end of the season she measured crop yield as the dry weight of the corn cobs in bushes per acre (bu/acre).

Featured scientist: Erika Foster from Colorado State University

Flesch–Kincaid Reading Grade Level = 8.9

Resources to pair with this Data Nugget:

11.12.18

Beetle, it’s cold outside!

Frozen lady beetles.

The activities are as follows:

Éste Data Nugget también está disponible en Español:

Walking across a snowy field or mountain, you might not notice many living things. But if you dig into the snow, you’ll find a lot of life!

Until recently, climate change scientists thought warming in winter would be good for most species. Warmer winters would mean that species could avoid the cold and would not need to deal with freezing temperatures as often or for as long. Caroline is a scientist who is thinking about winter climate change in a whole new way. Snow covers the soil, acting like an insulating blanket. Many species rely on the snow for protection from the winter’s cold. When temperatures climb in the winter, snow melts and leaves the soil uncovered for longer periods of time. This leads to the shocking pattern that warmer temperatures actually means the soil gets colder!

Caroline is interested in how species that rely on the snow will respond to climate change. She studies a species of insect called lady beetles. Lady beetles are ectotherms, meaning their body temperature matches that of their environment. Because climate change is reducing the amount of snow in the lady beetle habitat, Caroline wanted to know how they would respond to these changes.

Caroline and her team, Andre and Nikki, decided to investigate what happens to lady beetles when they are exposed to longer periods of time in cold temperatures. When soil temperatures drop below freezing (0℃), lady beetles go into a chill coma, or a temporary, reversible paralysis. When temperatures are below freezing, it is so cold that they are unable to move. When temperatures rise back above freezing, they wake from their chill comas. When lady beetles are in chill comas, they are easier for predators to catch because they can’t escape. They are also unable to find food or mates. Scientists can measure how fast it takes lady beetles to recover from chill coma, called chill coma recovery time, and use this as a measure of their performance.

Beetles in their pre-testing habitat are on the right; tubes with beetles about to be immersed in a cooler filled with crushed ice are on the left.

They designed an experiment to test whether the amount of time lady beetles spend in freezing temperatures affects how long it takes them to wake up from a chill coma. Caroline thought that lady beetles exposed to lengthy freezing temperatures would be harmed because freezing causes tissue damage and the insect must use more energy to survive. She predicted that the longer the lady beetles had been exposed to the cold, the longer it would take them to wake up from their chill comas.

To begin the experiment, Andre and Nikki placed groups of lady beetles in tubes. They then placed the tubes in an ice bath, bringing the temperature down to 0℃, the point when lady beetles enter chill coma. They varied the amount of time each tube was in the ice baths and tested chill coma recovery times after 3, 24, 48, 72, or 96 hours. After removing the tubes from the ice baths, they put the lady beetles on their backs with their legs in the air and left them at room temperature, 20℃. Andre and Nikki timed how long it took each beetle to wake up and turn itself over.

In the experiment, they used two different populations of lady beetles. Population 1 had been living in the lab for several weeks before the experiment began. They were not in great health and some had started to die. In order to make sure they had enough beetles for the experiment, Caroline purchased more lady beetles, which she called Population 2. Population 2 only spent a few days living in the lab before testing and were in much better health. Caroline noted the differences in these populations and thought their age, health, and background might affect how they respond to the experiment. She decided to track which population the lady beetles were from so she could analyze the data separately and see if the health differences between Population 1 and 2 changed the results.

Featured scientists: Caroline Williams & Andre Szejner Sigal, University of California, Berkeley, & Nikki Chambers, Biology Teacher, West High School, Torrance, CA

Flesch–Kincaid Reading Grade Level = 9.8

9.4.18

Alien life on Mars – caught in crystals?

Magnesium sulfate crystals trapping liquid water.

The activities are as follows:

Is there life on other planets besides Earth? This question is not just for science fiction. Scientists are actively exploring the possibility of life beyond Earth. The field of astrobiology seeks to understand how life in the universe began and evolved, and whether life exists elsewhere. Our own solar system contains a variety of planets and moons. In recent years scientists have also discovered thousands of planets around stars other than our Sun. So far, none of these places are exactly like Earth. Many planets have environments that would be very difficult for life as we know it to survive. However, there are life forms that exist in extreme environments that we can learn from. On Earth there are extremely hot or acidic environments like volcanic hot springs. Organisms also live in extremely cold places like Antarctic glacier ice. Environments with extremely high pressure, like hydrothermal vents on the ocean floor, also support life. If life can inhabit these extreme environments here on Earth, might extreme life forms exist elsewhere in the universe as well?

A view of the astrobiology lab.

Charles is an astrobiologist from Great Britain who is interested in finding life on other planets. The list of places that we might look for life grows longer every day. Charles thinks that a good place to start is right next door, on our neighboring planet, Mars. We know that Mars currently is cold, dry, and has a very thin atmosphere. Charles is curious to know whether there might still be places on Mars where life could exist, despite its extreme conditions.While there is no liquid water on the surface of Mars anymore, Mars once had a saltwater ocean covering much of its surface. The conditions on Mars used to be much more like Earth. Liquid water is essential for life as we know it. If there are places on Mars that still hold water, these could be great places to look for evidence of life. Charles thought that perhaps salt crystals, formed when these Martian oceans were evaporating, could trap pockets of liquid water.

Charles and his fellow researcher Nikki knew that there are a number of kinds of salts found in Martian soils, including chlorides, sulfates, perchlorates and others. They wanted to test their idea that water could get trapped when saltwater with these salts evaporate. They decided to compare the rate of evaporation for solutions with magnesium sulfate (MgSO4) with another commonsalt solution: sodium chloride, or table salt (NaCl). They chose to investigate these two salts because they are less toxic to life as we know it than many of the other chloride, perchlorate, or sulfate salts. Also, from reading the work of other scientists, Charles knows the Martian surface is particularly rich in magnesium sulfate.

Charles and Nikki measured precise quantities of saturated solutions of magnesium sulfate and sodium chloride and placed them into small containers. Plain water was used as a control. There were three replicate containers for each treatment – nine containers in total. They left the containers open to evaporate and recorded their mass daily. They kept collecting data until the mass stopped changing. At this point all of the liquid had evaporated or a salt crust had formed that was impermeable to evaporation. They then compared the final mass of the control containers to the other solutions. They also checked the resulting crusts for the presence or absence of permanent water-containing pockets. Charles and Nikki used these data to determine if either saltmakes crystals that can trap water in pockets when it evaporates.

Featured scientists: Charles Cockell, UK Centre for Astrobiology, University of Edinburgh, & Nikki Chambers, Astrobiology Teacher, West High School, Torrance, CA

Flesch–Kincaid Reading Grade Level = 8.7

Additional teacher resource related to this Data Nugget:

8.22.18

Clique wars: social conflict in daffodil cichlids

A male and female daffodil cichlid

The activities are as follows:

Have you ever thought about what it would be like to live completely alone, without contact with other people? Nowadays, humans are constantly connected by phones, texting, and social media. Our social interactions affect us in many unexpected ways. Strong social relationships can increase human lifespan, and lower the risk of cancer, cardiovascular disease, and depression. Social relationships are so important that they are actually a stronger predictor of premature death than smoking, obesity, or physical inactivity! Like humans, social interactions are important for other animals as well.

Jennifer is a behavioral ecologist who is interested in daffodil cichlids, a social species of fish from Lake Tanganyika, a Great Lake in Africa. Daffodil cichlids live in social groups of several small fish and one breeding pair. Each group defends its own rock cluster in the lake. The breeding male and female are the largest fist in the group, and the smaller fish help defend territory against predators and help care for newly hatched baby fish. About 200 social groups together make up a colony.

Social groups of daffodil cichlids in Lake Tanganyika

Behavior within a social group may be influenced by the presence of other groups in the colony. For example, neighboring groups can be a threat because they may try to take away territory or resources. After reading about previous research on social interactions in species that live in groups, Jennifer noticed there were very few studies that looked at how neighboring groups affected behavior within the group. Jennifer thought that the presence of neighboring groups may force the breeding pair to be less aggressive towards each other and work together to protect their group’s resources against the outside threat.

To test her idea, Jennifer formed breeding pairs of daffodil cichlids in an aquarium laboratory. She first observed the breeding pairs for any aggressive behaviors when they were isolated and could not see other groups. She observed each group for 30 minutes a day for 10 days. Next, Jennifer set up a clear barrier between the breeding pair and a neighboring group. The fish could see each other but not physically interact. Jennifer again watched the breeding pair and documented any aggressive behaviors to see how the presence of a neighboring group affected conflict within the pair. She again observed each group with neighbors for 30 minutes a day for 10 days.

During these behavioral tests, Jennifer counted the total number of behaviors done by the breeding pair. She measured several behaviors. Physical attacks were counted every time contact between the fish was made (biting or ramming each other). Aggressive displays were counted when fish give signals of aggression without making physical contact (raising their fins or swimming rapidly at another fish). Submissive behaviors, or actions used to prevent aggression between the breeding pair, were also counted. Finally, behaviors used to encourage social bonding were counted and are called affiliative behaviors. Jennifer predicted that the breeding pair would perform fewer physical attacks and aggressive displays when a neighboring group was present compared to when the breeding pair was alone. She also thought the breeding pair would perform more submissive and affiliative behaviors when the neighboring group was present. In this way, the presence of an outside group would impact the behaviors within a group.

Featured scientist: Jennifer Hellmann from The Ohio State University

Flesch–Kincaid Reading Grade Level = 11.3

8.16.18

Tree-killing beetles

A Colorado forest impacted by a mountain pine beetle outbreak. Notice the dead trees mixed with live trees. Forests like this with dead trees from mountain pine beetle outbreaks cover millions of acres across western North America.

The activities are as follows:

A beetle the size of a grain of rice seems insignificant compared to a vast forest. However, during outbreaks the number of mountain pine beetles can skyrocket, leading to the death of many trees. The beetles bore their way through tree bark and introduce blue stain fungi. The blue stain fungi kills the tree by blocking water movement. Recent outbreaks of mountain pine beetles killed millions of acres of lodgepole pine trees across western North America. Widespread tree death caused by mountain pine beetles can impact human safety, wildfires, nearby streamflow, and habitat for wildlife.

Mountain pine beetles are native to western North America and outbreak cycles are a natural process in these forests. However, the climate and forest conditions have been more favorable for mountain pine beetles during recent outbreaks than in the past. These conditions caused more severe outbreaks than those seen before.

Logs from mountain pine beetle killed lodgepole pine trees. The blue stain fungi is visible around the edge of each log. Mountain pine beetles introduce this fungus to the tree.

When Tony moved to Colorado, he drove through the mountains eager to see beautiful forests. The forest he saw was not the green forest he expected. Many of the trees were dead! Upon closer examination he realized that some forests had fewer dead trees than others. This caused him to wonder why certain areas were greatly impacted by the mountain pine beetles while others had fewer dead trees. Tony later got a job as a field technician for Colorado State University. During this job he measured trees in mountain forests. He carefully observed the forest and looked for patterns of where trees seemed to be dead and where they were alive.

Tony thought that the size of the trees in the forest might be related to whether they were attacked and killed by beetles. A larger tree might be easier for a beetle to find and might be a better source of food.To test this idea, Tony and a team of scientists visited many forests in northern Colorado. At each site they recorded the diameter of each tree’s trunk, which is a measure of the size of the tree. They also recorded the tree species and whether it was alive or dead. They then used these values to calculate the average tree size and the percent of trees killed for each site.

Featured scientist: Tony Vorster from Colorado State University

Flesch–Kincaid Reading Grade Level = 8.3

There is one scientific paper associated with the data in this Data Nugget. The citation and PDF of the paper is below:

Students can complete this Data Nugget along with Tony! In this video, Tony provides more background on how he became interested in doing research, how he collects his data, and details on how to construct graphs.

8.15.18

Are forests helping in the fight against climate change?

Bill setting up a large metal tower in Harvard Forest in 1989, used to measure long-term CO2 exchange.

The activities are as follows:

As humans drive cars and use electricity, we release carbon in the form of carbon dioxide (CO2) into the air. Because CO2 helps to trap heat near the surface of the earth, it is known as a greenhouse gas and contributes to climate change. However, carbon is also an important piece of natural ecosystems, because all living organisms contain carbon. For example, when plants photosynthesize, they take CO2 from the air and turn it into other forms of carbon: sugars for food and structural compounds to build their stems, roots, and leaves. When the carbon in a living tree’s trunk, roots, leaves, and branches stays there for a long time, the carbon is kept out of the air. This carbon storage helps reduce the amount of CO2 in the atmosphere. However, not all of the CO2 that trees take from the air during photosynthesis remains as part of the tree. Some of that carbon returns to the air during a process called respiration.

Another important part of the forest carbon cycle happens when trees drop their leaves and branches or die. The carbon that the tree has stored breaks down in a process called decomposition. Some of the stored carbon returns to the air as CO2, but the rest of the carbon in those dead leaves and branches builds up on the forest floor, slowly becoming soil. Once carbon is stored in soil, it stays there for a long time. We can think of forests as a balancing act between carbon building up in trees and soil, and carbon released to the air by decomposition and respiration. When a forest is building up more carbon than it is releasing, we call that area a carbon sink, because overall more CO2 is “sinking” into the forest and staying there. On the other hand, when more carbon is being released by the forest through decomposition and respiration, that area is a carbon source, because the forest is adding more carbon back into the atmosphere than it is taking in through photosynthesis.

In the 1990s, scientists began to wonder what role forests were having in this exchange of carbon in and out of the atmosphere. Were forests overall storing carbon (carbon sink), or releasing it (carbon source)? Bill is one of the scientists who decided to explore this question. Bill works at the Harvard Forest in central Massachusetts, a Long-Term Ecological Research site that specializes in setting up big experiments to learn how the environment works. Bill and his team of scientists realized they could measure the CO2 coming into and out of an entire forest. They built large metal towers that stand taller than the forest trees around them and use sensors to measure the speed, direction, and CO2 concentration of each puff of air that passes by. Bill compares the CO2 in the air coming from the forest to the ones moving down into the forest from the atmosphere. With the CO2 data from both directions, Bill calculates the Net Ecosystem Exchange (or NEE for short). When more carbon is moving into the forest than out, NEE is a negative number because CO2 is being taken out of the air. This often happens during the summer when trees are getting a lot of light and are therefore photosynthesizing. When more CO2 is leaving the forest, it means that decomposition and respiration are greater than photosynthesis and the NEE is a positive number. This typically happens at night and in the winter, when trees aren’t photosynthesizing but respiration and decomposition still occur. By adding up the NEE of each hour over a whole year, Bill finds the total amount of CO2 the forest is adding or removing from the atmosphere that year.

Bill and his team were very interested in understanding NEE because of how important it is to the global carbon cycle, and therefore to climate change. They wanted to know which factors might cause the NEE of a forest to vary. Bill and other scientists collected data on carbon entering and leaving Harvard Forest for many years to see if they could find any patterns in NEE over time. By looking at how the NEE changes over time, predictions can be made about the future: are forests taking up more CO2 than they release? Will they continue to do so under future climate change?

Featured scientist: Bill Munger from Harvard University. Written by: Fiona Jevon.

Flesch–Kincaid Reading Grade Level = 10.5

Additional teacher resource related to this Data Nugget:

  • There are several publications based on the data from the Harvard Forest LTER. Citations below:
    • Wofsy, S.C., Goulden, M.L., Munger, J.W., Fan, S.M., Bakwin, P.S., Daube, B.C., Bassow, S.L. and Bazzaz, F.A., 1993. Net exchange of CO2 in a mid-latitude forest. Science, 260(5112), pp.1314-1317.
    • Goulden, M.L., Munger, J.W., Fan, S.M., Daube, B.C. and Wofsy, S.C., 1996. Exchange of carbon dioxide by a deciduous forest: response to interannual climate variability. Science, 271(5255), pp.1576-1578.
    • Barford, C.C., Wofsy, S.C., Goulden, M.L., Munger, J.W., Pyle, E.H., Urbanski, S.P., Hutyra, L., Saleska, S.R., Fitzjarrald, D. and Moore, K., 2001. Factors controlling long-and short-term sequestration of atmospheric CO2 in a mid-latitude forest. Science, 294(5547), pp.1688-1691.
    • Urbanski, S., Barford, C., Wofsy, S., Kucharik, C., Pyle, E., Budney, J., McKain, K., Fitzjarrald, D., Czikowsky, M. and Munger, J.W., 2007. Factors controlling CO2 exchange on timescales from hourly to decadal at Harvard Forest. Journal of Geophysical Research: Biogeosciences, 112(G2).
    • Wehr, R., Munger, J.W., McManus, J.B., Nelson, D.D., Zahniser, M.S., Davidson, E.A., Wofsy, S.C. and Saleska, S.R., 2016. Seasonality of temperate forest photosynthesis and daytime respiration. Nature, 534(7609), p.680.
  • Our Changing Forests Schoolyard Ecology project – Do your students want to get involved with research monitoring carbon cycles in forests? Check out this hands-on field investigation, led by a team of Ecologists at Harvard Forest. Students can contribute to this study by monitoring a 20 meter by 20 meter plot in a wooded area near their schools.
  • Video showcasing 30 years of research at the Harvard Forest LTER
  • A cool article about the diversity of research being done at Harvard Forest – Researchers blown away by hurricane simulation
  • Additional images from Harvard Forest, diagrams of NEE, and a vocabulary list can be found in this PowerPoint.

5.11.18

Bringing back the Trumpeter Swan

Joe with a Trumpeter Swan.

The activities are as follows:

The Kellogg Bird Sanctuary was created in 1927 to provide safe nesting areas for waterfowl such as ducks, geese, and swans. During that time many waterfowl species were in trouble due to overhunting and the loss of wetland habitats. One species whose populations had declined a lot was the Trumpeter Swan. Trumpeter swans are the biggest native waterfowl species in North America. At one time they were found across North America, but by 1935 there were only 69 known individuals in the continental U.S.! The swans were no longer found in Michigan.

The reintroduction, or release of a species into an area where they no longer occur, is an important tool in helping them recover. In the 1980s, many biologists came together to create a Trumpeter Swan reintroduction plan. Trumpeter Swans in North America can be broken up into three populations – Pacific Coast, Rocky Mountain, and Interior. The Interior is further broken down into Mississippi/Atlantic and High Plains subpopulations. Joe, the Kellogg Bird Sanctuary manager and chief biologist, wrote and carried out a reintroduction plan for Michigan. Michigan is part of the Mississippi/Atlantic subpopulation. Joe and a team of biologists flew to Alaska in 1989 to collect swan eggs to be reared at the sanctuary. After two years the swans were released throughout Michigan.

The North American Trumpeter Swan survey has been conducted approximately every 5 years since 1968 as a way to estimate the number of swans throughout their breeding range. The survey is conducted in late summer when young swans can’t yet fly but are large enough to count. Although the surveys are conducted across North America, the data provided focuses on just the Interior Population, which includes swans in the High Plains and Mississippi/Atlantic Flyways.

Featured scientist: Wilbur C. “Joe” Johnson from the W.K. Kellogg Bird Sanctuary. Written by: Lisa Vormwald and Susan Magnoli from Michigan State University.

Flesch–Kincaid Reading Grade Level = 11.5

Additional teacher resource related to this Data Nugget:

A video on Trumpeter Swan reintroduction efforts that could be shown before the Data Nugget to engage students with the topic, or after to expand the research beyond the one study:

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4.16.18

The case of the collapsing soil

An area in the Florida Everglades where strange soil collapse has been observed.

The activities are as follows:

As winds blow through the large expanses of grass in the Florida Everglades, it looks like flowing water. This “river of grass” is home to a wide diversity of plants and animals, including both the American Alligator and the American Crocodile. The Everglades ecosystem is the largest sub-tropical wetland in North America. One third of Floridians rely on the Everglades for water. Unfortunately, this iconic wetland is threatened by rising sea levels caused by climate change. Sea level rise is caused by higher global temperatures leading to thermal expansion of water, land-ice melt, and changes in ocean currents.

With rising seas, one important feature of the Florida Everglades may change. There are currently large amounts of carbon stored in the wetland’s muddy soils. By holding carbon in the mud, coastal wetlands are able to help in the fight against climate change. However, under stressful conditions like being submersed in sea water, soil microbes increase respiration. During respiration, carbon stored in the soil is released as carbon dioxide (CO2), a greenhouse gas. As sea level rises, soil microbes are predicted to release stored carbon and contribute to the greenhouse effect, making climate change worse.

Shelby collecting soil samples from areas where the soil has collapsed in the Everglades.

Shelby and John are ecologists who work in southern Florida. John became fascinated with the Everglades during his first visit 10 years ago and has been studying this unique ecosystem ever since. Shelby is interested in learning how climate change will affect the environment, and the Everglades is a great place to start! They are both very concerned with protecting the Everglades and other wetlands. Recently when John, Shelby, and their fellow scientists were out working in the Everglades they noticed something very strange. It looked like areas of the wetland were collapsing! What could be the cause of this strange event?

John and Shelby thought it might have something to do loss of carbon due to sea level rise. They wanted to test whether the collapsing soils were the result of increased microbial respiration, leading to loss of carbon from the soil, due to stressful conditions from sea level rise. They set out to test two particular aspects of sea water that might be stressful to microbes – salt and phosphorus.

Phosphorus is found in sea water and is a nutrient essential for life. However, too much phosphorus can lead to over enriched soils and change the way that microbes use carbon. Sea water also contains salt, which can stress soil microbes and kill plants when there is too much. Previous research has shown that both salt and phosphorus exposure on their own increase respiration rates of soil microbes.

A photo of the experimental setup. Each container has a different level of salt and phosphorus concentration.

To test their hypotheses, a team of ecologists in John’s lab developed an experiment using soils from the Everglades. They collected soil from areas where the soil had collapsed and brought it into the lab. These soils had the microbes from the Everglades in them. Once in the lab, they put their soil and microbes into small vials and exposed them to 5 different concentrations of salt, and 5 different concentrations of phosphorus. The experiment crossed each level of the two treatments. This means they had soil in every possible combination of treatments – some with high salt and low phosphorus, some in low salt and high phosphorus, and so on. Their experiment ran for 5 weeks. At the end of the 5 weeks they measured the amount of CO2 released from the soils.

Featured scientists: John Kominoski and Shelby Servais from Florida International University. Written by Shelby, John, and Teresa Casal.

Flesch–Kincaid Reading Grade Level = 9.2

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