11.14.22

Does more rain make healthy bison babies?

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

The activities are as follows:

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

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

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

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

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

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

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

Featured scientist: Jeff Taylor from the Konza Prairie Biological Station

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

Flesch–Kincaid Reading Grade Level = 8.7

Additional teacher resources related to this Data Nugget include:

  • The full dataset for bison herd data is available online! The purpose of this study is to monitor long-term changes in individual animal weight. The datasets include an annual summary of the bison herd structure, end-of-season weights of individual animals, and maternal parentage of individual bison. The data in this activity came from the bison weight dataset (CBH012).
  • For more information on calf weight, check out the LTER Book Series book, The Autumn Calf, by Jill Haukos.
9.6.22

Changing climates in the Rocky Mountains

Lower elevation site in the Rocky Mountains: Temperate conifer forest. Photo Credit: Alice Stears.

The activities are as follows:

Each type of plant needs specific conditions to grow and thrive. If conditions change, such as temperature or the amount of precipitation, plant communities may change as well. For example, as the climate warms, plant species might start to shift to higher latitudes to follow the conditions where they grow best. But what if a species does well in cold climates found at the tops of mountains? Because they have nowhere to go, warming puts that plant species at risk.  

To figure out if species are moving, we need to know where they’ve lived in the past, and if climates are changing. One way that we can study both things is to use the Global Vegetation Project. The goal of this project is to curate a global database of plant photos that can be used by educators and students around the world. Any individual can upload photos and identify plant species. The project then connects each photo to information on the location’s biome, ecoregion, and climate, including data tracking precipitation and temperature over time. The platform can also be used to explore how the climates of different regions are changing and use that information to predict how plant communities may change. 

Daniel is a scientist who is interested in sharing the Global Vegetation Project data with students. Daniel became interested in plants and vegetation when he learned in college that you can simply walk through the woods and prairie, collect wild seeds, germinate the plants, and grow them to restore degraded landscapes. Plants set the backdrop for virtually every landscape that we see. He thinks plants deserve our undivided attention.

Daniel and his team wanted to create a resource where students can look deeper into plant communities and their climates. Much of the inspiration for the Global Vegetation Project came from the limitations to undergraduate field research during the COVID-19 pandemic. Students in ecology and botany classes, who would normally observe and study plants in the field, were prevented from having these opportunities. By building an online database with photos of plants, students can explore local plants without having to go into the field and can even see plants from faraway places. 

Daniel’s lab is based in the Rocky Mountains in Wyoming, where the plants are a showcase in both biodiversity and beauty. These communities deal with harsh conditions: cold, windy and snowy winters, hot and dry summers, and unpredictable weather during spring and fall. The plants rely on winter snow slowly melting over spring and into summer, providing moisture that can help them survive the dry summers. 

The Rocky Mountains are currently facing many changes due to climate change, including drought, increased summer temperatures, wildfires, and more. This creates additional challenges for the plants of the Rockies. Drought reduces the amount of precipitation, decreasing the amount of water available to plants. In addition, warmer temperatures in winter and spring shift more precipitation to rain instead of snow and melts snow more quickly. Rain and melted snow rapidly move through the landscape, becoming less available to plants in need. On top of all this, hotter, drier summers further decrease the amount of water available, stressing plants in an already harsh environment. If these trends continue, there could be significant impact on the types of plants that are able to grow in the Rocky Mountains. These changes will have an impact on the landscape, organisms that rely on plants, and humans as well.

Daniel and his colleagues pulled climate data from a Historic period (1961-2009) and Current period (2010-2018). They selected two locations in Wyoming to focus on: a lower elevation montane forest and a higher elevation site. To study climate, they focused on temperature and precipitation because they are important for plants. They wanted to study how temperature and precipitation patterns changed overall and how they changed in different seasons. They predicated temperatures would be higher in the Current period compared to the Historic period in both locations. For precipitation, they predicted there would be drier summers and wetter springs.

Featured scientist: Daniel Laughlin from The University of Wyoming. Written by: Matt Bisk.

Flesch–Kincaid Reading Grade Level = 10.5

Additional teacher resource related to this Data Nugget:

1.12.16

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.