Deadly windows

A white-throated sparrow caught during the experiment. You can see the band on it’s leg, used to make sure they did not record the same bird more than once.

The activities are as follows:

Glass makes for a great windowpane because you can see right through it. However, the fact that windows are see-through makes them very dangerous for birds. Have you ever accidentally run into a glass door, or been confused by a tall mirror in a restaurant? Just like people, birds can mistake a see-through window or a mirrored pane for an opening to fly through or a place to get food, and will accidentally fly into them. These window collisions can hurt the bird, or even kill it. Window collisions kill nearly 1 billion birds every year!

Urban areas, with lots of houses and stores, have a lot of windows. Resident birds that live in the area may get to know these buildings well, and may learn to avoid the windows. However, not all the birds in an area live there year-round. There are also migrant birds that fly through urban areas during their fall migrations. They will use gardens and parks in urban areas to rest along their journeys to their winter southern homes. During the fall migration, people have noticed that it seems like more birds fly into windows. This may be because migrant birds are not familiar with the local buildings. While looking for food and places to sleep, migrant birds might have more trouble identifying windows and fly into them more often. However, it could also be that there are simply more window collisions in the fall because there are more birds in the area when migrant and resident birds co-occur in urban areas.

Researchers identify the species of each bird caught in one of the nets used in the study. They then place a metal bracelet on one leg so they will know if they catch the same bird again.

Natasha was visiting a friend who worked at a zoo when he told her about a problem they were having. For a few weeks in the fall, they would find dead birds under the windows, more than they would during the rest of the year. He wanted to figure out a way to prevent birds from hitting the exhibit windows. Natasha became interested in learning whether migrant birds were more likely to fly into windows than resident birds, or if the number of window collisions only increase in the fall because there are lots of birds around. To do this she would have to count the total number of birds in the area, and also the total number of birds that were killed in window collisions. To count the total number of birds in the area, Natasha hung nets that were about the same height as windows. When the birds got caught in the nets, Natasha could count and identify them. This data could then be used to calculate the proportion of migrants and residents flying at window-height. She put ten nets up once a week for four hours, over the course of 3 months, and checked them every 15 minutes for any birds who got caught.

Researcher identifying a yellow-rumped warbler, one of the birds captured in the net as part of the study.

Then, she also checked under the windows in the same area to see what birds were killed from window collisions. She checked the windows every morning and evening for the three months of the study. Different species of bird are migratory or resident in the area where Natasha did her study. Each bird caught in nets was examined to identify it to species using its feathers, which would tell her whether the bird was a migrant or a resident. The same was done for birds found dead below windows.

If window collisions are really more dangerous for migrants, she predicted that a higher proportion of migrants would fly into windows than were caught in the nets. But, if window collisions were in the same proportion as the birds caught in the nets, she would have evidence that windows were just as dangerous for resident birds as for migrants.

Featured scientist: Natasha Hagemeyer from Old Dominion University

Flesch–Kincaid Reading Grade Level = 8.7

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

To engage students with the lesson before they begin, or after the lesson to help them develop their own independent questions for the system, you can share the following videos:

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Marsh makeover

A saltmarsh near Boston, MA being restored after it was degraded by human activity.

The activities are as follows:

Salt marshes are diverse and productive ecosystems, and are found where the land meets the sea. They contain very unique plant species that are able to tolerate flooding during high tide and greater salt levels found in seawater. Healthy salt marshes are filled with many species of native grasses. These grasses provide food and nesting grounds for lots of important animals. They also help remove pollution from the land before it reaches the sea. The grass roots protect the shoreline from erosion during powerful storms. Sadly today, humans have disturbed most of the salt marshes around the world. As salt marshes are disturbed, native plant biodiversity, and the services that marshes provide to us, are lost.

A very important role of salt marshes is that they are able to store carbon, and the amount they store is called their carbon storage capacity. Carbon is stored in marshes in the form of both dead and living plant tissue, called biomass. Marsh grasses photosynthesize, taking carbon dioxide out of the atmosphere and storing it in plant biomass. This biomass then falls into the mud and the carbon is stored there for a very long time. Salt marshes have waterlogged muddy soils that are low in oxygen. Because of the lack of oxygen, decomposition of dead plant tissue is much slower than it is in land habitats where oxygen is plentiful. All of this stored carbon can help lower the levels of carbon dioxide in our atmosphere. This means that healthy and diverse salt marshes are very important to help fight climate change.

However, as humans change the health of salt marshes, we may also change the amount of carbon being stored. As humans disturb marshes, they may lower the biodiversity and fewer plant species can grow in the area. The less plant species growing in the marsh, the less biomass there will be. Without biomass falling into the mud and getting trapped where there is little oxygen, the carbon storage capacity of disturbed marshes may go down.

Jennifer, working alongside students, to collect biomass data for a restored saltmarsh.

It is because of the important role that marshes play in climate change that Jennifer, and her students, spend a lot of time getting muddy in saltmarshes. Jennifer wants to know more about the carbon storage capacity of healthy marshes, and also those that have been disturbed by human activity. She also wants to know whether it is possible to restore degraded salt marshes to help improve their carbon storage capacity. Much of her work focuses on comparing how degraded and newly restored marshes to healthy marshes. By looking at the differences and similarities, she can document the ways that restoration can help increase carbon storage. Since Jennifer and her students work in urban areas with a lot of development along the coast, there are lots of degraded marshes that can be restored. If she can show how important restoring marshes is for increasing plant diversity and helping to combat climate change, then hopefully people in the area will spend more money and effort on marsh restoration.

Jennifer predicted that: 1) healthy marshes will have a higher diversity of native vegetation and greater biomass than degraded salt marshes, 2) restored marshes will have a lower or intermediate level of biomass depending on how long it has been since the marsh was restored, and 3) newly restored marshes will have lower biomass, while marshes that were restored further in the past will have higher biomass.

To test her predictions, Jennifer studied two different salt marshes near Boston, Massachusetts, called Oak Island and Neponset. Within each marsh she sampled several sites that had different restoration histories. She also included some degraded sites that had never been restored for a comparison. Jen measured the total number of different plant species and plant biomass at multiple locations across all study sites. These measurements would give Jen an idea of how much carbon was being stored at each of the sites.

Featured scientist: Jennifer Bowen from Northeastern University

Flesch–Kincaid Reading Grade Level = 11.0

When a species can’t stand the heat

An adult male tuatara. Photo by Scott Jarvie.

An adult male tuatara. Photo by Scott Jarvie.

The activities are as follows:

Tuatara are a unique species of reptile found only in New Zealand. While they look like lizards, they are actually in their own reptile group. Tuatara are the only species remaining on the planet from this lineage, one that dates back to the time of the dinosaurs! Similar to tortoises, they are extremely long-lived and can sometimes live over 100 years. Tuatara start reproducing when they are about 15-20 years old and they breed infrequently.

North Brother Island, one of the small New Zealand islands where tuatara are still found today.

North Brother Island, one of the small New Zealand islands where tuatara are still found today. Photo by Jo Monks.

The sex of tuatara is not determined by sex chromosomes (X or Y), as in humans. Instead, the temperature of the nest during egg development is the only factor that determines the sex of tuatara embryos. If the egg develops with a low temperature in the nest it will be female, but if it develops with a high temperature it will be male. This process happens in many other species too, including some turtles, crocodiles, lizards, and fish. However, most species are the opposite of tuatara, and produce females at the warmest temperatures.

Today, tuatara face many challenges. Humans introduced new predators to the large North and South Islands of New Zealand. Tuatara used to live on these main islands, but predators led them to local extinction. Today they survive only on smaller offshore islands where they can escape predation. Because many of these islands are small, tuatara can have low population numbers that are very vulnerable to a variety of risk factors. One of the current challenges faced by these populations is climate change. Similar to the rest of the world, climate change is resulting in temperatures that are getting higher and higher in New Zealand, and the warm temperatures may impact tuatara reproduction.

Kristine collecting data on a tuatara in the field.

Kristine collecting data on a tuatara in the field. Photo by Sue Keall.

North Brother Island has a small population of tuatara (350-500 individuals) that has been studied for decades. Each tuatara has been marked with a microchip (like the ones used on pet dogs and cats), which allows scientists to identify and measure the same individuals repeatedly across years. In the 1990s, a group of scientists studying tuatara on this island noticed that there were more males than females (60% males). The scientists started collecting data on the number of males and females so they could use long-term data to track whether the sex ratio, or the ratio of males and females in the population, became more balanced or became even more male-biased over time. The sex ratio is important because when there are fewer females in a population, there are fewer individuals that lay eggs and produce future offspring. Generally, a population that is highly male-biased will have lower reproduction rates than a population that is more balanced, or is female-biased.

Because tuatara are long-lived and breed infrequently, the scientists needed to follow the sex ratio for many years to be sure they were capturing a true shift in the sexes over time. In 2012, Kristine and her colleagues decided to use this long-term data to see if the sex ratio is changing as New Zealand warms. Since the temperature of the nest determines sex, and temperature is going up due to climate change, they predicted that there would be a greater proportion of males in the population over time. This would be reflected in an unbalanced sex ratio that is moving further and further away from 50% males and 50% females.

Graph showing mean annual temperatures for New Zealand, made by the National Institute of Water and Atmospheric Research. The y-axis represents the difference in that year’s mean temperature from the average temperature from 1981-2010. Red bars mean the year was warmer than average, and blue mean it was colder. The black line is the trend from 1909 to 2015 (0.92 ± 0.26°C/100 years).

Graph showing mean annual temperatures for New Zealand, made by the National Institute of Water and Atmospheric Research. The y-axis represents the difference in that year’s mean temperature from the average temperature from 1981-2010. Red bars mean the year was warmer than average, and blue mean it was colder. The black line is the trend from 1909 to 2015 (0.92 ± 0.26°C/100 years).

Featured scientists: Kristine Grayson from University of Richmond, Nicola Mitchell from University of Western Australia, and Nicola Nelson from Victoria University of Wellington

Flesch–Kincaid Reading Grade Level = 11.5

Additional teacher resources related to this Data Nugget:


kgAbout Kristine: Kristine L. Grayson received her Ph.D. in 2010 from the University of Virginia under the mentorship of Dr. Henry Wilbur. Her thesis used mark-recapture methods to examine migration behavior in a pond-breeding amphibian. She received an NSF International Research Fellowship to Victoria University of Wellington in New Zealand to conduct research on sex-ratio bias under climate change in tuatara, an endemic reptile. One of Kristine’s claims to fame is capturing the state record holding snapping turtle for North Carolina – 52 pounds! In addition to her passion for amphibian and reptile conservation, Kristine’s current work also examines the spread potential of gypsy moth, an invasive forest pest in North America. Kristine currently is an Assistant Professor in the Biology Department at University of Richmond.

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The Arctic is Melting – So What?

A view of sea ice in the Artic Ocean.

A view of sea ice in the Artic Ocean.

The activities are as follows:

Think of the North Pole as one big ice cube – a vast sheet of ice, only a few meters thick, floating over the Arctic Ocean. Historically, the amount of Arctic sea ice would be at a maximum in March. The cold temperatures over the long winter cause the ocean water to freeze and ice to accumulate. By September, the warm summer temperatures cause about 60% of the sea ice to melt every year. With global warming, more sea ice is melting than ever before. If more ice melts in the summer than is formed in the winter, the Arctic Ocean will become ice-free, and would change the Earth as we know it.

Student drills through lake ice

Student drills through lake ice

This loss of sea ice can have huge impacts on Arctic species and can also affect climate around the globe. For example, polar bears stand on the sea ice when they hunt. Without this platform they can’t catch their prey, leading to increased starvation. Beyond the Arctic, loss of sea ice can increase global climate change through the albedo effect (or the amount of incoming solar radiation that is reflected by a surface). Because ice is so white, it has high albedo and reflects a lot of the sunlight that hits it and keeps the earth cooler. Ice’s high albedo is why it seems so bright when the sun reflects off snow. When the ice melts and is replaced by water, which has a much lower albedo, more sunlight is absorbed by the earth’s surface and temperatures go up.

Scientists wanted to know whether the loss of sea ice and decreased albedo could affect extreme weather in the northern hemisphere. Extreme weather events are short-term atmospheric conditions that have been historically uncommon, like a very cold winter or a summer with a lot of rain. Extreme weather has important impacts on humans and nature. For example, for humans, extreme cold requires greater energy use to heat our homes and clear our roads, often increasing the use of fossil fuels. For wildlife, extreme cold could require changes in behavior, like finding more food, building better shelter, or a moving to a warmer location.

Student releases weather balloon

Student releases weather balloon

To make predictions about how the climate might change in the coming decades to centuries, scientists use climate models. Models are representations, often simplifications, of a structure or system used to make predictions. Climate models are incredibly complex. For example, climate models must describe, through mathematical equations, how water that evaporates in one region is transferred through the atmosphere to another region, potentially hundreds of miles away, and falls to the ground as precipitation.

James is a climate scientist who, along with his colleagues, wondered how the loss of arctic sea ice would affect climates around the globe. He used two well-established climate models – (1) the UK’s Hadley Centre model and (2) the US’s National Center for Atmospheric Research model. These models have been used previously by the Intergovernmental Panel on Climate Change (IPCC) to predict how much sea ice to expect in 2100.

Featured scientists: James Screen from University of Exeter, Clara Deser from National Center for Atmospheric Research, and Lantao Sun from University of Colorado at Boulder. Written by Erin Conlisk from Science Journal for Kids.

Flesch–Kincaid Reading Grade Level = 10.2

Earth Science Journal for KidsThis Data Nugget was adapted from a primary literature activity developed by Science Journal For KidsFor a more detailed version of this lesson plan, including a supplemental reading, videos, and extension activities, visit their website and register for free!

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

You can play this video, showing changes in Arctic sea ice from 1987-2014, overhead at the start of class (no sound required). Each student should write down a couple of observations and questions.

Bye bye birdie? Part II

In Part I, you examined the patterns of total bird abundance at Hubbard Brook Experimental ForestThese data showed bird numbers at Hubbard Brook have declined since 1969. Is this true for every species of bird? You will now examine data for four species of birds to see if each of these species follows the same trend.

Red-eyed vireo in the Hubbard Brook Experimental Forest

Red-eyed vireo in the Hubbard Brook Experimental Forest

The activities are as follows:

It is very hard to study migratory birds because they are at Hubbard Brook only during their breeding season (summer in the Northern Hemisphere). They spend the rest of their time in the neotropics or migrating between their two homes. Therefore, it can be difficult to tease out the many variables affecting bird populations over their entire range. To start, scientists decided to focus on what they could study—the habitat types at Hubbard Brook and how they might affect bird populations.

Hubbard Brook Forest was heavily logged and disturbed in the early 1900s. Trees were cut down to make wood products, like paper and housing materials. Logging ended in 1915, and various plants began to grow back. The area went through secondary succession, which refers to the naturally occurring changes in forest structure that happen as a forest recovers after it was cut down or otherwise disturbed. Today, the forest has grown back. Scientists know that as the forest grew older, its structure changed: Trees grew taller, and there was less shrubby understory. It contains a mixture of deciduous trees that lose their leaves in the winter (about 80–90%; mostly beech, maples, and birches) and evergreen trees that stay green all year (about 10–20%; mostly hemlock, spruce, and fir).

Richard and his fellow scientists used their knowledge of bird species and thought that some bird species prefer habitats found in younger forests, while others prefer habitats found in older forests. They decided to look into the habitat preferences of four important species of birds—Least Flycatcher, Red-eyed Vireo, Black-throated Green Warbler, and American Redstart—and compare them to habitats available at each stage of succession.

  • Least Flycatcher: The Least Flycatcher prefers to live in semi-open, mid-successional forests. The term mid-successional refers to forests that are still growing back after a disturbance. These forests usually consist of trees that are all about the same age and have a thick canopy at the top with few gaps, an open middle canopy, and a denser shrub layer close to the ground.
  • Black-throated Green Warbler: The Black-throated Green Warbler occupies a wide variety of habitats. It seems to prefer areas where deciduous and evergreen forests meet and can be found in both forest types. It avoids disturbed areas and forests that are just beginning succession. This species prefers both mid-successional and mature forests.
  • Red-eyed Vireo: The Red-eyed Vireo breeds in deciduous forests as well as forests that are mixed with deciduous and evergreen trees. They are abundant deep in the center of a forest. They avoid areas where trees have been cut down and do not live near the edge. After an area is logged, it often takes a very long time for this species to return.
  • American Redstart: The American Redstart generally prefers moist, deciduous, forests with many shrubs. Like the Least Flycatcher, this species prefers mid-successional forests.

birds

Featured scientist: Richard Holmes from the Hubbard Brook Experimental Forest. Data Nugget written by: Sarah Turtle and Jackie Wilson.

Flesch–Kincaid Reading Grade Level = 10.2

A view of the Hubbard Brook Experimental Forest

A view of the Hubbard Brook Experimental Forest

Additional teacher resource related to this Data Nugget:

There are two publications related to the data included in this activity:

  • Holmes, R. T. 2010. Birds in northern hardwoods ecosystems: Long-term research on population and community processes in the Hubbard Brook Experimental Forest. Forest Ecology and Management doi:10.1016/j.foreco.2010.06.021
  • Holmes, R.T., 2007. Understanding population change in migratory songbirds: long-term and experimental studies of Neotropical migrants in breeding and wintering areas. Ibis 149 (Suppl. 2), 2-13

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Bye bye birdie? Part I

Male Black-throated Blue Warbler feeding nestlings. Nests of this species are built typically less than one meter above ground in a shrub such as hobblebush. Photo by N. Rodenhouse.

Male Black-throated Blue Warbler feeding nestlings. Nests of this species are built typically less than one meter above ground in a shrub such as hobblebush. Photo by N. Rodenhouse.

The activities are as follows:

The Hubbard Brook Experimental Forest is an area where scientists have collected ecological data for many years. It is located in the White Mountains of New Hampshire, and data collected in this forest helps uncover trends that happen over long periods of time. It is important to collect data on ecosystems over time, because these patterns could be missed with shorter experiments.

Richard Holmes is an avian ecologist who began this study because he was interested in how bird populations were responding to long-term environmental change.

Richard Holmes is an avian ecologist who began this study because he was interested in how bird populations were responding to long-term environmental change.

Each spring, Hubbard Brook comes alive with the arrival of migratory birds. Many migrate from wintering areas in the tropics to take advantage of the abundant insects and the long summer days of northern areas, which are beneficial when raising young. Avian ecologists, scientists who study the ecology of birds, have been keeping records on the birds that live in the experimental forest for over 40 years. These data are important because they represent one of the longest bird studies ever conducted!

Richard is an avian ecologist who began this study. He was interested in how bird populations were responding to long-term environmental changes in Hubbard Brook. Every summer since 1969, Richard takes his team of scientists, students, and technicians into the field to count the number of birds that are in the forest and identify which species are present. Richard’s team monitors populations of over 30 different bird species. They wake up every morning before the sun rises and travel to the far reaches of the forest. They listen for, look for, identify, and count all the birds they find. The scientists record the number of birds observed in four different study areas, each of which are 10 hectare in size – roughly the same size as 19 football fields! Each of the four study areas contain data collection points that are arranged in transects that run east to west along the valley. Transects are parallel lines along which the measurements are taken. Each transect is approximately 500m apart from the next. At each point on each transect, an observer stands for ten minutes recording all birds seen or heard during a ten minute interval, and estimates the distance the bird is from the observer. The team has been trained to be able to identify the birds by sight, but also by their calls. Team members are even able to identify how far away a bird is by hearing its call! The entire valley is covered three times a season. By looking at bird abundance data, Richard can identify trends that reveal how avian populations change over time.

Featured scientist: Richard Holmes from the Hubbard Brook Experimental Forest. Data Nugget written by: Sarah Turtle, Jackie Wilson and Elizabeth Schultheis.

Flesch–Kincaid Reading Grade Level = 10.6

A view of the Hubbard Brook Experimental Forest

A view of the Hubbard Brook Experimental Forest

Additional teacher resource related to this Data Nugget:

There are two publications related to the data included in this activity:

  • Holmes, R. T. 2010. Birds in northern hardwoods ecosystems: Long-term research on population and community processes in the Hubbard Brook Experimental Forest. Forest Ecology and Management doi:10.1016/j.foreco.2010.06.021
  • Holmes, R.T., 2007. Understanding population change in migratory songbirds: long-term and experimental studies of Neotropical migrants in breeding and wintering areas. Ibis 149 (Suppl. 2), 2-13

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Does sea level rise harm Saltmarsh Sparrows?

Painting of the saltmarsh sparrow

Painting of the saltmarsh sparrow

The activities are as follows:

For the last 100 years, sea levels around the globe have increased dramatically. The cause of sea level rise has been investigated and debated. Data from around the world supports the hypothesis that increasing sea levels are a result of climate change caused by the burning of fossil fuels. As we warm the Earth, the oceans get warmer and polar ice caps melt. The dramatic increase in sea level that results could seriously threaten ecosystems and the land that humans have developed along the coast.

Salt marshes are plains of grass that grow along the east coast of the United States and many coasts worldwide. Salt marshes grow right at sea level and are therefore very sensitive to sea level rise. In Boston Harbor, Massachusetts, the NOAA (National Oceanic and Atmospheric Administration) Tide Gauge has measured a 21mm rise in sea level over the last 8 years. That means every year sea level has gone up an average of 2.6mm since 2008 – more than two and a half times faster than before we started burning fossil fuels! Because sea level is going up at such a fast rate, Robert, a scientist in Boston, became concerned for the local salt marsh habitats near his home. Robert was curious about what will happen to species that depend on Boston’s Plum Island Sound salt marshes when sea levels continue to rise.

Robert preparing his team for a morning of salt marsh bird surveys.

Robert preparing his team for a morning of salt marsh bird surveys.

Robert decided to look at species that are very sensitive to changes in the salt marsh. When these sensitive species are present, they indicate the marsh is healthy. When these species are no longer found in the salt marsh, there might be something wrong. The Saltmarsh Sparrow is one of the few bird species that builds its nests in the salt marsh, and is totally dependent on this habitat. Saltmarsh Sparrows rely completely on salt marshes for feeding and nesting, and therefore their numbers are expected to decline as sea levels rise and they lose nesting sites. Robert heard that scientists studying Connecticut marshes reported the nests of these sparrows have been flooded in recent years. He wanted to know if the sparrows in Massachusetts were also losing their nests because of high sea levels.

For the past two decades Robert has kept track of salt marsh breeding birds at Plum Island Sound. In his surveys since 2006, Robert counted the number of Saltmarsh Sparrows in a given area. He did these surveys in June when birds are most likely to be breeding. He used the “point count” method – standing at a center point he measured out a 100 meter circle around him. Then, for 10 minutes, he counted how many and what kinds of birds he saw or heard within and just outside the circle. Each year he set up six count circles and performed counts three times in June each year at each circle. Robert also used sea level data from Boston Harbor that he can relate to the data from his bird surveys. He predicted that sea levels would be rising in Plum Island Sound and Saltmarsh Sparrow populations would be falling over time.

Featured scientist: Robert Buchsbaum from Mass Audubon. Written by: Wendy Castagna, Daniel Gesin, Mike McCarthy, and Laura Johnson

Flesch–Kincaid Reading Grade Level = 9.5

Saltmarsh-Sparrow-104-crAdditional teacher resources related to this Data Nugget include:

coordinates

station locations

What Do Trees Know About Rain?

A cypress pine, or Callitris columellaris. This species is able to survive in Australia’s dry climates.

A cypress pine, or Callitris columellaris. This species is able to survive in Australia’s dry climates.

The activities are as follows:

Did you know that Australia is the driest inhabited continent in the world? Because it is so dry, we need to be able to predict how often and how much rain will fall. Predictions about future droughts help farmers care for their crops, cities plan their water use, and scientists better understand how ecosystems will change. The typical climate of arid northwest Australia consists of long drought periods with a few very wet years sprinkled in. Scientists predict that climate change will cause these cycles to become more extreme – droughts will become longer and periods of rain will become wetter. When variability is the norm, how can scientists tell if the climate is changing and droughts and rain events today are more intense than what we’ve seen in the past?

To make rainfall predictions for the future, scientists need data on past rainfall. However, humans have only recorded rainfall in Australia for the past 100 years. Because climate changes slowly and goes through long-term cycles, scientists need very long term datasets of rainfall.

Scientist Alison coring a cypress pine

Scientist Alison coring a cypress pine

The answer to this challenge comes from trees! Using dendrochronology, the study of tree rings, scientists get a window back in time. Many tree species add a ring to their trunks every year. The width of this ring varies from year to year depending on how much water is available. If it rains a lot in a year, the tree grows relatively fast and ends up with a wide tree ring. If there isn’t much rain in a year, the tree doesn’t grow much and the ring is narrow. We can compare the width of rings from recent years to the known rain data humans have collected. Then, assuming the same forces that determine tree ring width are operating today as in the past, we can go back and interpret how much rain fell in years where we have no recorded rainfall data. This indirect information from tree rings is known as a proxy, and helps us infer data about past climates.

For this study, the scientists used cypress-pine, or Callitris columellaris. This species is able to survive in Australia’s dry climates and is long lived enough to provide data far back in time. Fortunately, scientists don’t have to cut down the trees to see their rings. Instead, they use a corer – a hollow metal drill with the diameter of a straw. They drill it through the tree all the way to its core, and extract a sample of the tissue that shows all the tree rings. The scientists took 40 cores from 27 different cypress-pine trees. The oldest trees in the sample were more than 200 years old. Next, they developed a chronology where they lined up ring widths from one tree with all the other trees, wide with wide and narrow with narrow. This chronology gives them many replicate samples, and data going back all the way to the 19th century! Next, they used a dataset of rainfall from rain gauges that have been set out in Australia since 1910. They then take this precipitation data and overlay it with the tree ring widths since 1910. For tree rings before 1910, they then project back in time using a rainfall formula.

These videos, demonstrating the science of dendrochronology, could be a great way to spark class discussions:

Featured scientist: Alison O’Donnell from University of Western Australia

Flesch–Kincaid Reading Grade Level = 8.0

Earth Science Journal for KidsThis Data Nugget was adapted from a primary literature activity developed by Science Journal For Kids. For a more detailed version of this lesson plan, including a supplemental reading, videos, and extension activities, visit their website and register for free!

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

Growth rings from a Callitirs tree.

Growth rings from a Callitirs tree.

Lizards, Iguanas, and Snakes! Oh My!

The Common Side-blotched Lizard

The Common Side-blotched Lizard

The activities are as follows:

Throughout history people have settled mainly along rivers and streams. Easy access to water provides resources to support many people living in one area. In the United States today, people have settled along 70% of rivers.

Today, rivers are very different from what they were like before people settled near them. The land surrounding these rivers, called riparian habitats, has been transformed into land for farming, businesses, or housing for people. This urbanization has caused the loss of green spaces that provide valuable services, such as water filtration, species diversity, and a connection to nature for people living in cities. Today, people are trying to restore green spaces along the river to bring back these services. Restoration of disturbed riparian habitats will hopefully bring back native species and all the other benefits these habitats provide.

Scientist Mélanie searching for reptiles in the Central Arizona-Phoenix LTER.

Scientist Mélanie searching for reptiles in the Central Arizona-Phoenix LTER.

Scientists Heather and Mélanie are researchers with the Central Arizona-Phoenix Long-Term Ecological Research (CAP LTER) project. They want to know how restoration will affect animals living near rivers. They are particularly interested in reptiles, such as lizards. Reptiles play important roles in riparian habitats. Reptiles help energy flow and nutrient cycling. This means that if reptiles live in restored riparian habitats, they could increase the long-term health of those habitats. Reptiles can also offer clues about the condition of an ecosystem. Areas where reptiles are found are usually in better condition than areas where reptiles do not live.

Heather and Mélanie wanted to look at how disturbances in riparian habitats affected reptiles. They wanted to know if reptile abundance (number of individuals) and diversity (number of species) would be different in areas that were more developed. Some reptile species may be sensitive to urbanization, but if these habitats are restored their diversity and abundance might increase or return to pre-urbanization levels. The scientists collected data along the Salt River in Arizona. They had three sites: 1) a non-urban site, 2) an urban disturbed site, and 3) an urban rehabilitated site. They counted reptiles that they saw during a survey. At each site, they searched 21 plots that were 10 meters wide and 20 meters long. The sites were located along 7 transects, or paths measured out to collect data. Transects were laid out along the riparian habitat of the stream and there were 3 plots per transect. Each plot was surveyed 5 times. They searched for animals on the ground, under rocks, and in trees and shrubs.

Featured scientists: Heather Bateman and Mélanie Banville from Arizona State University. Written by Monica Elser from Arizona State University.

Meet the scientist! Click here to watch a video where scientist Heather explains her research!

Flesch–Kincaid Reading Grade Level = 9.8

Invasion Meltdown: Will Climate Change Make Invasions Even Worse?

The invasive plant, Centaurea stoebe

The invasive plant, Centaurea stoebe

The activities are as follows:

Humans are changing the earth in many ways, including warming the planet by burning fossil fuels and adding greenhouse gasses to the atmosphere. Scientists have documented rising temperatures across the globe and predict an increase of 3° C in Michigan within the next 100 years. Humans are also changing the earth by transporting species across the globe, introducing them into new habitats. These introduced species may cause problems in their new habitats. Additionally, increasing temperature from climate change may change the way that native and introduced plants and animals interact.

All living organisms have a range of temperatures they are able to survive in, and temperatures where they perform their best. For example, arctic penguins do best in the cold, while tropical parrots prefer warmer temperatures. The same is true for plants. Depending on the temperature preferences of a plant species, warming temperatures due to climate change may either help or harm that species.

Scientists collecting abundance and performance data on the plants in the heating rings.

Scientists collecting abundance and performance data on the plants in the heating rings.

Scientists are concerned that invasive species may do better in the warmer temperatures caused by climate change. Invasive species have been introduced from one area into another, and now thrive in their new habitat. Invasive species harm native species and cause many problems for humans. There are several reasons to expect that invasive species may benefit from climate change. First, because invasive species have already survived transport from one habitat to another, they may be species that are better able to handle change, such as temperature changes. Second, the new habitat of an invasive species may have temperatures that allow it to survive, but are too low for the invasive species to do their absolute best. This could happen if the invasive species was transported from somewhere warm to somewhere cold. Climate change could increase temperatures enough to put the new habitat in the species’ range of preferred temperatures, making it ideal for the invasive species to grow and survive.

A view of the plants growing in a heated ring. Notice the purple flowers of Centaurea stoebe.

A view of the plants growing in a heated ring.
Notice the purple flowers of Centaurea stoebe.

To determine if climate change will benefit invasive species, scientists at Michigan State University focused on one of the worst invasive plants in Michigan, Centaurea stoebe (spotted knapweed). They looked at Centaurea plants growing in a field experiment with eight rings. Half of the rings were left with normal, ambient air temperatures. The other half of the rings were heated using ceramic heaters attached to the side of the rings. These heaters successfully raised air temperatures by 3° C. At the end of the summer, the scientists collected all of the Centaurea plants from the rings. They recorded both the (1) abundance, or number of Centaurea plants within a square meter, and (2) the biomass (dry weight of living material) of the plants in a square meter as a measure of performance.

Featured scientists: Katie McKinley, Mark Hammond, and Jen Lau from Michigan State University

Flesch–Kincaid Reading Grade Level = 8.6