12.8.25

The science of stamen loss

A pollinator visiting a mustard flower, drinking nectar and picking up pollen from anthers.

The activities are as follows:

Plants and animals have adaptations, or traits that help them survive and pass on more of their genes to the next generation. Flowers are a key adaptation for plants because they help the attract pollinators and reproduce.

Flowers come in many different shapes, sizes, colors, and forms. While flowers as a whole are an adaptation, traits within flowers are often adaptations themselves. For example, different flower colors attract different types of animals to the plant. Some flowers make nectar that gives animals a food reward for visiting. Other plants have small flowers with no petals so that pollen can be easily picked up and travel by wind.

Many of the animals that visit the plant serve as pollinators. Pollinators help plants reproduce by bringing reproductive parts together. Pollination happens when pollen from the stamen reaches the stigma. This is needed for seeds to form. By moving pollen, pollinators help plants make more seeds. More seeds lead to more plants in the next generation. Small differences in flower traits can change which plant is the most successful at reproducing and setting seed.

Jeff is a scientist studying a very particular flower shape seen in plants of the mustard family. Most plants in this family have flowers with 4 long stamens and 2 short stamens. No other plants have this shape, and no one knows why! The short stamens are a particular mystery.

Jeff wanted to see why mustards might have these short stamens. He thought that short stamens are an adaptation because they make it harder for pollinators to reach the pollen, so that more pollen would be left over for later pollinators. This might be beneficial because the first pollinator visiting the flower wouldn’t be able to take all the pollen, leaving none for the following visitors. If his hypothesis was correct, he predicted that short stamens would have less pollen removed with each pollinator visit compared the long stamens.

Members of the Conner Lab taking measurements of pollen found on the anthers of short and long stamens.

To collect his data, Jeff and other scientists in his lab needed to measure how much pollen was removed by pollinators on short and long stamens. To do this, they grew mustard plants in the greenhouse and let them flower. This made sure no pollinators could visit the plants before the experiment. Next, they exposed the plants to the three most common pollinators for mustards – bumblebees, small bees, and syrphid flies. To test honeybees, plants were put into flight cages with bees inside. To test small bees and syrphids, plants were put outside. Pollinators chose the flower to visit. After each visit, the lab counted the pollen on the visited flower. They then compared it to the amount of pollen on a flower that was not visited. They used these values to calculate the percent pollen removed. This was repeated for short and long stamens.

Featured scientists: Jeff Conner (he/him) from the W.K. Kellogg Biological Station. Written with Kirsten Salonga, Justice High School, Research Experience for Teachers.

Flesch–Kincaid Reading Grade Level = 7.6

Additional teacher resource related to this Data Nugget:

The data featured in this activity has been published. If you are interested in having students read primary scientific literature, they can complete this Data Nugget and then explore the full study here: 

10.15.25

Stormy shorelines

A scientist adding water to simulate flooding.

The activities are as follows:

Chevak is a village that sits along the Ningliqvak River in Alaska. The area around the village is a flat coastal wetland, a landscape of winding river channels, marshes, and salty lakes. In the Yup’ik language, this low-lying terrain is called maraq. Here, salt-tolerant grasses and sedges thrive in an environment with brackish water, which is saltier than fresh water, but less salty than sea water. These wetlands serve as nesting grounds for waterfowl during the spring and summer months.

Further upland, the higher ground that sits roughly three meters in elevation is called nunapik, meaning tundra. Brackish water does not usually touch these areas. The tundra has many freshwater lakes and supports a different plant community, rich with forbs, shrubs, and lichen. Because it experiences less flooding, more types of plants can live in the upland tundra, providing important resources for food and medicine.

In recent years, coastal flooding has become more common near Chevak. Protective sea ice melts earlier each year. Storm surges and rising sea levels now push brackish water further inland. These flooding events increase erosion, damage property, and alter the delicate balance of wetland and tundra ecosystems.

Ecologists Karen, Kathy, and Josh began studying the plants around Chevak to better understand how flooding affects these ecosystems. To understand how plant communities at high and low elevations respond to flooding, the scientists designed an experiment at Old Chevak, the original village site abandoned decades ago due to flooding.

Chevak, a village in Alaska.

Working in collaboration with the Chevak community and the Yukon Delta National Wildlife Refuge, they established experimental plots to simulate flooding. The flooded plots were created by pumping in seawater to simulate high-tide flooding. This was repeated 3 times during the summer. Karen, Kathy, and Josh also kept control plots where no brackish water was added. The treatments were repeated at both high and low elevation sites. There were 7 replicates at each location.

At the summer’s end the team collected data on plant growth. They measured the biomass, or weight, of all plants in all of the plots. Karen, Kathy, and Josh grouped the plants into 4 groups. Graminoids, which include grasses and sedges, are the dominant plant group of the maraq. They typically grow well in flooded wetland areas. Forbs are broadleaf herbs, like salmonberries, that grow well in the nunapik. Shrubs include species such as blueberries, cranberries, and tundra tea. Like forbs, they also grow well in the nunapik. Lichens are plant-like species that form low crusts along the ground and are only found in the higher elevation sites.

Karen, Kathy, and Josh thought that plants from the low elevation sites would be made up of more salt and flood-tolerant species and would therefore be less harmed by frequent floods. On the other hand, high elevation sites would consist mostly of plant species that are not salt or flood-tolerant and would not do well during floods.

Featured scientists: Karen Beard (she/her) of Utah State University, Kathy Kelsey (she/her) of the University of Colorado Denver and Joshua Leffler (he/him) of South Dakota State University. Written by: Andrea Pokrzywinski (she/her).

Flesch–Kincaid Reading Grade Level = 8.9

Additional Resources:

The video, “Voices from the Land” introduces the collaboration between scientists and Yup’ik community members. They are working together to respect and care for the land. This narrative is told by the students from Bethel and Chevak Alaska. 

This activity pairs with another Data Nugget, “Salmonberries in our future”, which features this same collaboration, but focuses on one culturally significant type of Arctic plant, salmonberries.

9.20.25

Salmonberries in our future

Picking salmonberries is a cultural tradition for many Alaskans.

The activities are as follows:

In the Yup’ik and Cup’ik Native communities of western Alaska, berry picking is a deeply rooted tradition. Many villages are located more than 500 miles from the nearest road system or grocery store. Fresh fruits and vegetables from other places are flown in by small planes at significant cost. This makes local berries a lifeline for these remote villages.

Salmonberries (also known as cloudberries) are one type of Arctic berry. They are prized for their wonderful taste. Salmonberries are rich in nutrients like vitamin C, antioxidants, and essential minerals. One cup of salmonberries alone can meet a person’s daily vitamin C needs. In addition to humans, these berries provide nutrients to other animals, such as migrating birds, small mammals, and bears.

During berry season, families travel across the land to gather berries, preserve them, and store them for the winter. Families use a vast web of winding rivers to travel by boat to reach their berry picking camps. These western Alaska rivers flow towards the Bering Sea, where freshwater mixes with salty ocean tides.

Rubus chamaemorus, known as salmonberry in western Alaska, ready to be picked.

This mix of saltwater and freshwater shapes the tundra landscape. Tough, salt-tolerant plants, like grasses and sedges, often dominate low-lying areas closest to the sea. Slightly higher ground, just above the reach of the tides, provides a more suitable home for berries. These subtle shifts in water levels play a large role in determining where berries can grow.

Ecologists Karen, Kathy, and Joshua are collaborating with Native communities to learn more about how changes in climate are affecting berry plants. They are studying two major changes already observed under climate change – warming and flooding. Over time, warming and flooding combined could change the entire makeup of plant communities. This will affect whether local families are able to continue their traditions and access this valuable food source.

Alaska’s average temperatures are increasing, more so than other parts of the globe. This warming might help some plants by extending the growing season. With more time and sunlight, salmonberries and other plants may actually grow faster.

Climate change is also expected to increase flooding in some areas of coastal Alaska. Storms are already becoming stronger and more frequent, pushing seawater farther inland. Because of this, flooding events are increasing in frequency. Rising sea levels and storm surges may kill salmonberry plants because these plants are not adapted to having their roots submerged in salty water.

To tease apart the effects of warming and flooding, Karen, Kathy, and Joshua designed a field experiment to simulate climate change. They built clear plastic structures, called open-topped chambers, to trap heat and raise the temperature by about 2°C. These chambers can be thought of as mini time machines, creating small areas that have the expected temperatures of the coming decades. Next, they created flooded plots using brackish, or slightly salty, water that they collected where the fresh river water meets the sea. They used this water to simulate flooding events in the plots. In the end, their experiment had four different types of plots: (1) Control plots with no warming or flooding, (2) plots that were warmed, (3) plots that were flooded, and (4) plots that were both warmed and flooded. 

They let these treatments run the full growing season. After that time, the team collected data on salmonberry growth. Karen, Kathy, and Joshua measured both the height and biomass of salmonberry plants in all of the plots. These two measures are good estimates of how many berries the plants will produce – the larger the plant, the more berries it can make. They were very precise in their measurements; in a place where food and traditions are tied to the land, every berry matters.

Note: Cloudberries (Rubus chamaemorus) are regionally known as “salmonberries” in western Alaska, and “Naunrat”, “Atsaq/Atsisaq”, or “Atsalugpiaq” in Yup’ik and Cup’ik. In southeast Alaska, a related but different species, Rubus spectabilis, produces berries that are known as salmonberry in that region. In this activity, we will be referencing Rubus chamaemorus.

Featured scientists: Karen Beard (she/her) of Utah State University, Kathy Kelsey (she/her) of the University of Colorado Denver, and Joshua Leffler (he/him) of South Dakota State University. Written by: Andrea Pokrzywinski (she/her).

Flesch–Kincaid Reading Grade Level = 5.7

8.27.25

Can kelp help the plovers? 

Beach hopper on a sidewalk

The activities are as follows:

It’s a beach day! You’re walking through the sand on a southern California beach, looking for a place to put your things. You notice there are clumps of dried-up seaweed everywhere. As you brush aside some of these clumps to lay out your towel, a shrimp-like bug jumps out at you and bounces off your hand! With smelly dried seaweed, small birds skittering across the sand, and hopping bugs, you wonder, is this beach healthy? Yes! These are all parts of a thriving food web.

Beaches are home to many important species that each play a role in the ecosystem. On the Pacific Coast of California, the dried-up seaweed is typically made up of several species of kelp. Kelp captures the sun’s energy through photosynthesis. Beach hoppers, the little jumping “bugs”, are actually small crustaceans
that feed on the kelp. In turn, these beach hoppers are the main food source for birds.

Snowy plovers are a type of bird that loves to eat beach hoppers. This shorebird species is threatened in California due to habitat loss. The sandy beaches where the plovers live and nest are also places where people like to walk and play. Scientists want to better understand what makes up the base of the food web that supports plovers to help their populations recover.

High school seniors, Mari and Azra, visited beaches in Lompoc, a coastal city in California, many times with their science classes. They wanted to learn more about the sandy beach ecosystem, so they read an article from a local research group at the University of California-Santa Barbara. On one of their field trips, they learned about a scientist named Jenny Dugan. Jenny and members of her lab study the beach hoppers’ important role in the sandy beach ecosystem. The Dugan lab had done a series of experiments to see what types of kelp beach hoppers liked to eat.

Azra (left) and Mari (right) working with kelp.

Mari and Azra wanted to set up a similar experiment to see if the beach hoppers in the Lompoc area preferred the same species of kelp. Their teacher, Ms. Moore, collected beach hoppers, sand, and kelp on her way to school one day. Mari and Azra set up ten plastic containers by measuring an equal amount of damp sand and punching holes in the lids. Then they tried to put 10 beach hoppers into the container. But it was hard to know the exact number until the very end of the experiment because some would hop out before the lid was on! At the end of the study, the number ranged from 8-15 beach hoppers in each container. Finally, Mari and Azra weighed out 15.0 grams of kelp and put it on top of the sand in the containers. They put one type of kelp in each container. Four containers had feather boa kelp, Egregia, four containers had giant kelp, Macrocystis, and two containers had Laminaria, another type of kelp. Mari and Azra also set up controls for each type of kelp with sand and kelp, but no beach hoppers. This container would tell them how much kelp weight was lost to water evaporation over the 3 days of the experiment, and not due to being eaten.

Trial 1: Mari and Azra placed the containers outside in a shady spot for three days. On the third morning, they opened up the containers to weigh the kelp that remained. Before weighing the kelp, they rinsed it to remove excess sand and dried it gently to remove excess water. Finally, they counted the beach hoppers that were in the container.

Trial 2: After reviewing their results from this experiment, Mari and Azra realized the beach hoppers did not like Laminaria at all. They decided to repeat the experiment using kelp and beach hoppers from a different beach, and did not include Laminaria as a food source.

Featured scientists: Mari and Azra from Lompoc High School, California. Jenny Dugan from the University of California-Santa Barbara. Written by: Melissa Moore from Lompoc High School.

Flesch–Kincaid Reading Grade Level = 8.1

8.20.25

Anole’s new niche

Yoel looking for lizards on a spoil island.
Photo Credit: Adam Algar

The activities are as follows:

Throughout our history, humans have been moving species around the world. In your own backyard there are likely multiple species that have come from different countries and mixed into your local ecosystem. Human movement of species has sped up in the last 150 years as we have gotten better at traveling by trains, planes, boats, and cars.

An open question is, what happens to species when they are moved around? Scientists can study both the species that have been moved, called introduced species, and the original species that were there before, called native species.

One interesting system to study is the anole lizard populations in Florida. In this case, there is both an introduced species that arrived relatively recently, the brown anole, and a species that has been there for much longer, the green anole.

The story of these two anoles and their interactions begins millions of years ago when both the green anole and the brown anole evolved in Cuba. They had different niches, or areas of specialization in their ecosystem when they lived there together. The green anole mostly perched high up on tree trunks, moving through branches and leaves as it looked for insects to eat. The brown anole preferred to perch lower down, finding its food on the ground and the lower part of tree trunks.

The Green Anole (Anolis carolinensis) and the Brown Anole (Anolis sagrei). Photo Credit: Adam Algar

Then, 2-4 million years ago, the green anole established a new population in Florida. How it did this, we are not sure. But it probably was blown by hurricanes from Cuba to Florida on rafts of trees and other vegetation. Once in Florida, it spread throughout the southeastern United States. As best we can tell, the green anole changed its niche once it was in the United States without the brown anole around. Data from previous research suggest that it started finding insect prey on the ground and perched lower down in the tree trunks.

Then, in the 1950s, the brown anole came to southern Florida through human movement on boats. This probably happened because humans were moving agricultural products (like sugar cane) from Cuba to the United States.

Yoel is a scientist studying anoles, and he wanted to know how green anoles respond to the recent presence of the brown anole. Now that they are together in Florida, the two anole species interact a lot.

Looking south at Spoil Islands along the Intracoastal Waterway shipping channel in Mosquito Lagoon. Photo credit: Todd Campbell

They both have a large population, they eat similar insects, and likely compete for food and space. Yoel thought the green anoles might respond by changing their behavior and habitat use. Yoel predicted that the green anoles would return to the treetops once the brown anole arrived, living like their ancestors did with the brown anole in Cuba. He also thought that the brown anole would keep low on the tree trunks, because that is where it has always perched while it coexisted with the green anoles in Cuba.

To test his hypothesis, Yoel’s team worked on eleven islands that were approximately the size of football-fields in Mosquito Lagoon, Florida. All eleven islands had green anole populations on them. Six of the eleven islands also had brown anole populations present on them. This meant that five islands only had one species, the green anole.

This created an ideal “natural experiment” to collect data on how green anoles use the habitat when they are alone, compared with when they are living on islands with the brown anole. To do this, Yoel collected data on perch height. He and his team did this by walking through the island habitats slowly until they spotted a lizard. Then, they measured the height of the spot where the lizards were sitting in the trees.

Featured scientists: Featured scientist: Yoel Stuart (he/him) from Loyola University Chicago

Flesch–Kincaid Reading Grade Level = 9.0

7.5.25

Catching fish with sound

Mei next to the research vessel, Endeavor

The activities are as follows:

In our ocean, the connections between the environment and marine organisms are intricate and complex. The watery surroundings connect each level of the food web – including marine mammals, large fish, schooling fish, phytoplankton, and more. Climate change is causing our ocean to become warmer, and organisms are already starting to respond. When ocean waters change, the effects cascade through different levels of the food web. In order to understand how marine organisms, and their interactions, are affected by changing climate, we need accurate measurements that tell us what populations are like today and continue monitoring into the future.
As a biological oceanographer, Mei’s research focuses on organisms in the middle of marine food webs. These are the small schooling fish, like anchovies and herring, that consume other organisms, but are also vulnerable to predation. Growing up in Japan, the ocean was always a part of Mei’s life through hobbies such as swimming, fishing, and also from knowing the cultural importance of eating seafood and learning to prepare for tsunamis. She was first introduced to ocean science through a local fisher who had an oyster farm near her hometown. Since then, she has pursued her career as an oceanographer across three different countries – Japan, Canada, and the United States – both in academia and industry.

Mei now does research as part of a Long-Term Ecological Research project out of Massachusetts. This means that Mei is part of a scientist team working together to study long-term patterns in the ocean.
Looking at data over time allows Mei and others to better identify and understand the consequences of climate change. This information Mei next to the research vessel, Endeavor will help fishers and fisheries managers make decisions and prepare for the future.

Mei testing equipment before a research cruise

In August 2023, Mei went to sea on one of the project’s research cruises. She wanted to take a closer look at one of the fastest-warming ocean areas and richest fisheries in the world – the continental shelf of the Northeast U.S. She boarded a large research ship for 6 days with a team of 14 other scientists who specialize in different areas of oceanographic research. To more accurately collect these data, Mei used sound! Echosounders bounce sound off marine organisms, such as fish. This tool is similar to fish finders that are used by most fishing boats. However, the technology used by Mei is more sensitive and provides more detailed data.
The amount of sound that comes back to the ship after bouncing off fish or anything in the water is called volume backscattering strength, and is measured in decibels (dB). The intensity of what comes back can serve as a measure of fish abundance. If there are more fish, the number becomes larger (less negative).
While the echosounder is operating, other members of the research team measure water temperature and other parameters from the surface to near the bottom. Temperature is measured in degrees Celsius (ºC), and depth is recorded in meters (m). Mei wanted to use these data to give her a snapshot in time of where fish are located.

Featured scientist: Mei Sato (she/her) from Woods Hole Oceanographic Institution and
Northeast U.S. Shelf LTER (NES-LTER)

Flesch–Kincaid Reading Grade Level = 9.8

7.5.25

Bear Necessities: A genetic panel for bear identification

Baby black bear, Murray.

The activities are as follows:

North Carolina is home to many black bears. As human development expands into bear habitats, conflicts between people and bears are becoming more common. In these situations, identifying individual bears and understanding their origins is essential. This ensures that wildlife officials can correctly manage aggressive or relocated bears. It also allows for better tracking of bear populations and their movements across the state, helping to inform long-term conservation approaches.

Though each individual bear has its own genotype, or unique genetic makeup, individuals within the same population often share more DNA with each other than with members of other populations. A group of scientists started comparing the DNA of black bears in California and identified 11 unique regions, called loci, in the DNA of bears from different populations. This set of loci that the scientists can use to assign individual black bears to different populations is called Ursaplex.

Each loci have microsatellites, which are repetitive sequences of nucleotide bases that vary between individuals or populations. Different versions of the microsatellite loci are called alleles. By examining these patterns in a bear’s genotype, scientists can identify bears at an individual level and tell which population they are from.

Isabella is a wildlife geneticist who studies how we can use genetic tools to conserve wild animal populations. She has always been passionate about animals and conservation. Isabella, along with other scientists, wants to test whether or not the Ursaplex panel could work for black bears in North Carolina.

North Carolina bears are split into three different management groups based on where they are found: Mountain, Piedmont, and Coastal. Isabella wanted to know whether black bears show genetic differences based on which management group they live in. If so, she wanted to see if any of the microsatellites in the Ursaplex panel could be used to identify which management group a bear is from.

Isabella obtained blood or saliva samplesfor350black bears from collaborators at the Wildlife Resource Commission, the state agency for wildlife management. The samples came from bears in the Mountain and Coastal management groups. The Piedmont bear population is significantly smaller and elusive, so samples from Piedmont bears were not available. She extracted the DNA from the samples and found the genetic sequence at each of the 11 loci in Ursaplex. Isabella looked at then umber of nucleotide base repeats in each bear’s genetic sequence and used the data to identify any patterns based on where the bear was from. Each of the 11 loci included arebi-allelic, meaning each bear will have two copies of the locus (one from their mom and one from their dad). Recently, Isabella received a blood sample from a new baby bear, Murray, who was rescued by wildlife managers. This baby bear was alone when he was found, so we don’t know where in the state he came from. He was found in the Eastern part of the state, so Isabella thought that his parents were likely both Coastal management group bears.

Featured scientists: Isabella Livingston (she/her) from North Carolina State University Written with Kate Price

Flesch–Kincaid Reading Grade Level = 9.6

6.13.25

What grows when the forest goes?

Area of the H.J. Andrews Experimental Forest in Oregon, a few years after a fire.

The activities are as follows:

The H.J. Andrews Experimental Forest, or Andrews for short, is a long-term ecological research site in the Cascade Mountains of Oregon. The forest is a temperate old-growth rainforest. It is known for its lush and green understory of flowering plants, ferns, mosses and a towering canopy of Douglas fir, Western hemlock, Red cedar, and other trees. Scientists have spent decades studying how plants, animals, land use, and climate are all connected in this ecosystem.

Matt is a biology teacher who has spent two summers in the field working with scientists at the Andrews. These experiences have been valuable ways to bring real data and research back to his students! When he visits, Matt works closely with Joe and Cole. Joe is a scientist who has spent many years working in the forest studying the impact of disturbances on plants. Cole is in Joe’s lab and has been focusing on fire’s effects on the forest during graduate school.

Historically, large, severe fires have been a part of the ecology of forests in Oregon. They typically occur every 200-500 years. Many of the plants at the Andrews Forest are those that can deal with fire. Fires clear out dead plants, return nutrients to the soil, and promote new growth of understory and canopy plants. With climate change impacting temperature and rainfall across the globe, forests in Oregon are increasingly experiencing longer periods of dry and hot weather. These changes are causing an increase in the frequency and severity of wildfires.  

On Matt’s last day at the Andrews in 2023, a lightning strike started a wildfire in a far corner of the forest. With hundreds of firefighters on the ground and several helicopters in the air, the “Lookout Fire” burned for several months, consuming about 70% of the Andrews forest! 

Plots in 2023 being surveyed for native and invasive plants to calculate the proportion that are invasive after a burn.

When Matt returned in the summer of 2024, it looked nothing like the forest he had left. The fire completely changed the course of his research experience. When he saw the scorched forest, he began to wonder how it would recover. He also observed that the fire had not burned at the same intensity throughout the forest. Some areas of Andrews were burned more, and in some spots, the fire had been less intense.  

Matt thought that some plants may do better after a severe burn, while other species might do worse. Specifically, Matt wanted to see whether native and invasive plants would show differences after a fire. Plants that have historically grown in an area without human interference are called native plants. These plants have a long history of adapting to the specific conditions in an area. When a plant species is moved by humans to a new area and grows outside of its natural range, it is called an invasive plant. Invasives often grow large and fast, taking over habitats, and pushing out native species. Invasive plants tend to be the ones that can grow fast and handle disturbances, so the team expected that invasive species would recover more quickly than native plants after high severity fires.  

It was still too early to re-enter the areas burned by the Lookout Fire, so Matt and Joe chose another recent fire. They used data collected from a section of the forest that had burned in 2020. In 2021, a year after the fire, scientists put out 80 plots that were 1m2 in size to collect data on the understory plants. 

Each section was given a burn severity value based on the amount the canopy trees had burned directly over the plot. Scientists would look up at the tree canopy and see how much was missing, and the more that was gone, they knew the burn severity had been higher. Scientists then identified every species of plant in the plots and counted the number of individual plants of each species. This was repeated every year after 2021 to observe changes over time. Matt and Joe decided to analyze data from 2023, which Matt helped collect with Cole. To answer their question, they calculated the proportion of invasive plants in each plot. 

Featured scientists: Joe LaManna (he/him) and Cole Doolittle (he/him) from Marquette University and
Matt Retterath (he/him) from Fridley Public Schools.

Flesch–Kincaid Reading Grade Level = 8.9

Additional teacher resources related to this Data Nugget:

There are two blog posts written about the Andrews LTER research featured in this activity.

  • https://lternet.edu/stories/fire-brings-new-perspectives-on-disturbance-at-h-j-andrews-experimental-forest/
  • https://lternet.edu/stories/burned-forest-bleached-reef-lter-sites-adapt-to-learn-from-disturbance/

5.30.25

CO2 and trees, too much of a good thing?

The activities are as follows:

Kristina conducting the tree survey, measuring the size of a tree, which will later be used to calculate the mass of carbon in that tree.

The amount of carbon dioxide (CO2) in the atmosphere has steadily increased since the start of the Industrial Revolution in 1750. This extra CO2 traps heat like a blanket, causing the global climate to warm. The resulting climate change effect is known and widely accepted in science. While scientists are certain that climate change is happening, they still have many questions about its impacts.

For example, scientists today are exploring whether climate change will help or hurt trees and forests. Many scientists think that elevated CO2 in the atmosphere can actually help trees. We can see why in the formula for photosynthesis:

6𝐶𝑂2+6𝐻2𝑂+𝐸𝑛𝑒𝑟𝑔𝑦→𝐶6𝐻12𝑂6 +6𝑂2

Carbon Dioxide + Water + Energy (sunlight) → Glucose + Oxygen

If you add more CO2 to the atmosphere, trees will have more resources for photosynthesis and can make more glucose. Glucose is food for the trees. Trees can use their glucose for growth, using it to make wood. However, trees sometimes have to put glucose towards other things. Just like us, plants break down glucose for energy through cellular respiration:

C6𝐻12𝑂6 +62→ 6𝐶𝑂2+6𝐻2𝑂+𝐸𝑛𝑒𝑟𝑔𝑦
Glucose + Oxygen → Carbon Dioxide + Water + Energy (ATP)

Two large trees stand in the experimental plot after a survey. The tree to the right has been banded to measure its growth.

Trees need energy for everyday functioning, or to respond to stress. Under climate change, trees might experience more stress. Stress for trees might increase if summer temperatures get too hot, or they don’t have enough water. More stress means more respiration and less growth. Or, even worse, the trees could die. Dead trees can’t photosynthesize, and they also decompose, which releases CO2 into the atmosphere
as microbes break down wood and other materials.

Kristina and Luca are scientists looking at the effects of climate change on trees. They wanted to test whether climate change was benefitting or hurting trees. They set out to find some data that would allow them to test these alternative hypotheses.

A dead ash tree stands in the experimental plot after a survey. The carbon in this tree
will return to the atmosphere through decomposition.

Kristina runs a tree census in a forest at the Smithsonian Conservation Biology Center in Virginia. Since 2008, she and many other scientists have surveyed every tree in their 26-hectare plot. Every five years, they count up how many trees are alive, how much they’ve grown, and how many have died. Luca joined Kristina’s lab in 2022. He and Kristina worked together with many other scientists to collect and process data on tree growth and mortality in 2023.

They used this growth and mortality data for individual trees to calculate levels of carbon gained and lost by the whole forest. The amount of carbon used for growth across the whole forest was measured as the mass of carbon gained. They also calculated the weight of the trees that died, which was measured as the mass of carbon lost. Both of these measurements were calculated in megagrams (Mg, that’s one million grams) of carbon (C) per hectare (ha) of forest per year (yr), or (MgC/ha/yr). The difference between these
two values is the change in carbon. This value gives the balance between carbon gained and lost. A positive value means there is more carbon being taken in by the forest than lost, and a negative value means that more carbon is being lost back to the atmosphere.

Featured scientists: Kristina J. Anderson-Teixeira (she/her) & Luca Morreale (he/him) at Smithsonian’s National Zoo & Conservation Biology Institute. Written by Ryan Helcoski

Flesch–Kincaid Reading Grade Level = 7.8

5.14.25

PFAS: Our forever problem

This image has an empty alt attribute; its file name is gary-headshot.png
Gary during his research experience with Natalia.

The activities are as follows:

Per- and polyfluoroalkyl substances (PFAS) are a group of pollutants that are found in many commonly used products. They are in clothing, non-stick pans, and even the linings of cans and other food containers. Because PFAS are used in so many everyday products, they make their way into the environment. Once these compounds are in our environment, they will be there for up to a thousand years! For this reason, PFAS are known as “forever chemicals.”

Water is a very common place to find these forever chemicals. Normal water treatment processes do not remove PFAS from our drinking water. Consequently, PFAS are found in the blood of humans and animals worldwide. In humans, they have been shown to cause liver damage, cancer, harm immune systems, and other health issues.

Natalia is a researcher at Florida International University who studies PFAS and other chemicals in the environment. She wanted to make sure she shared her work with the public, as this topic is so important for us all. She thought one way to do this would be to work with local teachers.

Gary, a science teacher at a school nearby, joined Natalia’s lab for the summer. When the opportunity became available, Gary jumped at the chance to investigate and learn more about Florida’s amazing environment and work in the field with scientists. He was so excited because Natalia had appeared on TV and radio shows and had authored articles in leading science magazines. When they met, Natalia described PFAS to Gary, and he was immediately captivated.

Gary and Natalia decided to work together to explore PFAS in Biscayne Bay. This area is a crucial estuary around Miami, providing a unique environment that supports diverse wildlife and local industries. As a young person, Gary would go shrimping along the bay. He really enjoyed the natural beauty of such a precious resource right in his backyard. Unfortunately, today, Biscayne Bay faces numerous
environmental challenges.

Map showing Gary’s research sites where he sampled PFAS

One challenge is PFAS, which enters the estuary through water pollution that drains into the bay. Gary expected PFAS to be highest in the urban freshwater streams that drain into the bay because human activity is high, and a lot of chemicals are released into the water. He thought that the bay would also have high concentrations of PFAS because the streams drain into the bay, but the surrounding land limits the water from mixing with the ocean. Once the water makes it to the ocean, the chemicals should be able to mix with the larger body of water, lowering the concentration of PFAS.

Gary and Natalia identified 16 water sampling sites in water bodies near Miami. They broke these sites into three categories: (1) freshwater rivers that bring water from urban areas into the bay, (2) brackish water, which means a mixture of freshwater and saltwater, located within Biscayne Bay, and (3) salt water found in the Atlantic Ocean. Courtney, a graduate student in Natalia’s lab, joined the team to assist Gary with collecting data and using the technical instruments needed to analyze the samples. Together, they collected one 500 mL sample from each site. To ensure accuracy in the collection of data, they collected two samples from the South Beach pump station site. Gary and Natalia brought the samples back to the lab and ran the samples through instruments that measured PFAS levels. Gary predicted that he would find high levels of PFAS in the freshwater canals and the brackish water of Biscayne Bay, but less in the open ocean.

Featured scientists: Gary Yoham from Miami Senior High School with Natalia Soares Quinete and Courtney Heath from Florida International University

Flesch–Kincaid Reading Grade Level = 7.3

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