10.12.26

Grass grows where giants fall

The site of an elephant carcass that has decomposed.

When an animal dies, it might seem like the end of its story. But in nature, death can be the beginning of something new. Dead plants and animals slowly break down over time. As they decompose, their matter is recycled back into the ecosystem. Microbes, insects, scavengers, soil, and plants all help break down the remains and use the nutrients.

Recycling matter is especially important when the dead animal is as big as an elephant! An African bush elephant can weigh several thousand kilograms. That is bigger than most vehicles. When an elephant dies, its dead body, called a carcass, does not just disappear. Even though scavengers and predators eat a lot of the carcass, they still leave behind pieces that are harder to digest.

For years, Ryan and Ndzalama worked together in Kruger National Park, South Africa. They studied decomposition cycles at sites that had an elephant carcass. They met while studying elephant behavior around carcass sites in the park. Together, they set up cameras and watched as elephants spent time at these sites and noticed how the sites changed over time. They observed that elephant carcasses can change the plant community around it for years. This might be because nutrients from the carcass can move into the soil and eventually become part of new plant growth. Ryan and Ndzalama thought that elephant carcasses could create pulses of intense nutrients that previously limited grass growth at the site. They predicted there would be more grass growing close to the carcass than farther away.

They worked in Kruger, a savanna ecosystem that also has many other large animal species. Plains zebra, African buffalo, blue wildebeest, impala, and white rhinos all live there. These animals, and many others, are grazers, meaning they mostly eat grass. Ryan and Ndzalama realized that to measure grass growth in a place with so many grazers would be difficult. The animals could eat the grass before the researchers collected data. So, together with an international team, they figured out a way to keep the grazers out.

Ndzalama inside one of the exlosure treatment plots.

To start, they chose sites throughout the park where an elephant carcass had been decomposing for about 6 months. The carcass had mostly disappeared, and grass had begun to grow around a barren area of soil in the center. At these sites, they built small 1 m² cages called exclosures. An exclosure keeps large grazing animals out, but still lets sunlight and rain reach the grass. They set up exclosures at several distances from the carcass site: 2.5 meters (m), 5 m, 10 m, and 15 m. They also paired an open plot, or control, next to each exclosure where animals could graze normally. For each distance, they set up 14 replicates.

At the start of their study, they clipped all the grass down to the dirt. This way, all plots started with grass at the same height, and they only measured grass that grew during their study. Then, they let the grass grow for a full season. At the end of the growing season, they clipped and weighed the grass from each plot to measure dry biomass, or the mass of dried plant material. For analysis, they averaged the results from the 14 replicates of each treatment and distance.

Featured scientists: Ryan Helcoski (he/him) from Utah State University and Ndzalama Mkansi (he/him) from South African National Parks

Flesch–Kincaid Reading Grade Level = 8.0

Additional Teacher Resources:

  • Check out the Megacarcass Ecology Working Group, which includes the research in this activity, along with many more projects about the ecology associated with megafauna caracasses. On the research page, you can find short videos and animations.
  • A video of Ryan and Kulani in the field introducing the study system and nutrient cycles in the African savanna ecosystem (10 min).
  • Nutrient cycle diagrams – a Google Drive folder with student and teaching files for the water, carbon, nitrogen, and phosphorus cycles that can be used to supplement this activity.
  • A radio series by Utah Public Radio about research in Kruger National Park, South Africa. Produced by Ryan Helcoski, a featured researcher in this activity, each short clip is only 2-5 minutes long.
  • A blog post called “Where there’s death, there’s life: the ecological impacts of megacarcasses.”
  • This research has been published in scientific journals. Here is one relevant article:  Reed, C. G., Budny, M. L., du Toit, J. T., Helcoski, R., Schimel, J. P., Smit, I. P. J., Strydom, T., Tallian, A., Thompson, D. I., van Coller, H., Lemoine, N. P., and Burkepile, D. E. 2024. Elephant megacarcasses increase local nutrient pools in African savanna soils and plants, EGUsphere [preprint].
12.23.25

Growing kelp for community

A grow line on a kelp farm in Prince William Sound, Alaska.

The activities are as follows:

When thinking about farming, many people imagine fields of corn or soybeans, or even their own vegetable garden. All of these crops are grown on land, but what about growing food in the ocean? Alaska Natives who live along the coast have been harvesting kelp, a group of seaweeds, from the wild for thousands of years. Kelp is very nutritious and is full of vitamins and minerals. It is used in a variety of dishes, from soups to salads. Kelp also provides structure for herring to lay their eggs, another traditional food source that coastal Alaska Native communities harvest. Kelp has other purposes too, including soil fertilizer and food additive applications.

Recently, there has been a surge of interest in farming kelp at a larger scale along the Alaskan coast. Farming kelp involves cultivating kelp at a site to grow larger for harvest. Caitlin is a biologist who works for the Native Village of Eyak within the Prince William Sound of Alaska. The Tribe wants to start a kelp farm to provide a nutritious food source for its community members. Caitlin was tasked with designing the farm setup and testing how much kelp can be grown. Her first step was to find a site. She had to consider environmental factors that help the kelp grow. Kelp need particular nutrients and cool water temperatures. She also had to make sure the site was easy to get to and that it was protected from intense weather like high winds and large waves. 

To get started, Caitlin talked to the members of the Eyak community to learn where they have historically found kelp, called Traditional Knowledge. She listened to their suggestions, which were based on current and long-term connections with the local environment. This helped her identify a site that is a short boat ride. Caitlin also had discussions with other kelp farmers in Alaska and read scientific research articles to learn more about how to set up a kelp farm and which species would be a good fit. She decided to grow sugar kelp because it has a sweeter taste and grows well in other places with similar conditions. 

She designed the farm to grow the kelp vertically in the water. To do this, she would place lines vertically in the water for kelp to attach and grow at different depths. This design maximizes the amount of kelp grown below the surface, which is good to minimize interference with boats and animals. While vertical lines have benefits, there could be drawbacks too. Kelp needs sunlight for photosynthesis, which it uses to grow. But the deeper you go in the water, the less sunlight there is. The kelp at the surface will get plenty of light, but the kelp attached to the line in deeper water might not get enough. The kelp at the bottom could also get blocked or shaded by the kelp above it. 

Caitlin wanted to know if there is a time of year when kelp had the fastest growth rates. This information would help her know when to harvest kelp from the site. She also wanted to know whether depth affected the kelp growth. If it turned out that kelp didn’t grow on her vertical lines in deeper water, she may have to try another design. She predicted that kelp grown in the first 1-2 meters from the surface would grow more over a season because it would receive the most sunlight. 

To assess her kelp farm plan, Caitlin worked with partners to seed lines with fertilized sugar kelp spores. Each of these spores can grow into a large kelp blade that can be up to 5 meters long. The seeded lines were then installed vertically at the farm site in the fall of 2022. Caitlin and her colleagues set up 532 vertical lines that were each 10 meters long. In total, over 2 miles of seeded line were installed on the farm! The lines were attached to a horizontal line to secure them in place and were spaced out so they had room to grow. 

Each month, Caitlin and her colleagues monitored the kelp growth by measuring the length of kelp blades, or leaf-like structures, on 5-8 of the seeded lines. On each line, they measured kelp blades at different depths so they could see how the kelp was growing at different depths.

Left: seed line one week after planting in November. Middle: kelp at the farm in April. Right: kelp blades after the harvest in June. 

Featured scientist: Caitlin McKinstry (she/her) from the Native Village of Eyak. Written with Rosel Burt and Melissa Kjelvik from Prince William Sound College.

This material is based upon work supported by the National Science Foundation under award #OIA-2344553 and by the State of Alaska.

Flesch–Kincaid Reading Grade Level = 7.4

Additional teacher resource related to this Data Nugget:

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:

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.

Additional video resources and lesson extensions can be found at the project website “Working Together”, including the following:

  • “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. 
  • “Mapping Merbok” describes the questions scientists are researching to document how increased flooding, such as that from Typhoon Merbok, will drive landscape changes.
  • “Warming and Flooding on the Tundra” describes the research scientists are conducting to measure the impact of both warming and flooding on plant communities.