Dr. Christine Jurasinski                     LabLearner Staff Scientist

Interdependence.  It’s a word that comes up when talking about virtually everything in today’s world, from climate change to the global economy.  When students in the LabLearner Program hear it they are likely to think about ecosystems and the relationship between producers, consumers and detrivores (decomposers such as scavengers, and microbes), and between prey and predator. For 4^th grade LabLearner students, interdependence is explored through their study of food chains and food webs in the Ecosystems and Adaptation CELL. 8^th grade LabLearner students take this knowledge farther investigating the flow of energy and biomass within ecosystems in the Ecosystems CELL. In addition, both elementary and middle school LabLearner students focus on how competition between herbivores or predation of herbivores by carnivores could increase or decrease the production of producers.  For example, the more herbivores killed by carnivores or omnivores, the fewer herbivores to consume producers and the more producer biomass that will result.

This concept of the effect of competition and predator/prey relationship on producers has long been thought to be the mechanism by which carnivores influenced the diversity and abundance of producers in ecosystems.  Now, new research from wildlife biologists at Michigan Technological University has suggested that carnivores may have a more direct and important effect on producers and the diversity of producers within ecosystems.

Joseph Bump, Rolf Peterson and John Vucetich have been studying the relationship between two parts of the ecosystem at Isle Royale National Park in Michigan: moose (herbivores) and wolves (carnivores).  Their most recent findings have produced what they describe as a somewhat surprising link between the prey/predator relationship and the producers in the ecosystem.   Bump, Peterson and Vucetich studied a 50 year record of the moose/wolf relationship that included observing the location of over 3600 moose carcasses. In addition, they conducted a 3.5 year study that compared the plant growth, soil microbes and fungi,  and nutrient deposition in plant leaves and soil from control sites and those containing carcasses of wolf killed moose.  Control sites were those that did not have moose carcasses. What they found was that soil at the wolf killed moose sites had 100 to 600 percent more potassium, nitrogen and phosphorus than soil at the control sites.  In addition, plants from the wolf killed moose sites possessed 25 to almost 50 percent more nitrogen than plants from control sites.  Bacteria and fungi were also higher at the wolf killed moose sites than the control sites.

When they combined this data with the 50 year record of moose carcasses what they found were “hot spots” of forest fertility- places in which nutrient, microbe and plant life were enriched.   In essence, the researchers say that the wolf/moose prey/predator relationship created a cycle in which the decomposition of moose carcasses increased the nutrient deposition of the soil, resulting in an increase in the amount of plant (producer) biomass and an increase in the nutrient composition of the plants.  Moose, which are attracted to nitrogen rich plants, were then drawn to these nutrient rich locations, depositing feces and urine further increasing the nutrient deposition into the soil.  In addition, the increase in moose frequency to these areas increased the likelihood of predation by wolves and ultimately the increase of even more moose carcasses.

While these findings may seem intuitive, they are shockingly new to the study of ecosystems, which up to this point, has not had evidence of such a direct relationship between predators and soil fertility.   In addition, the finding also suggests that there may be a direct relationship between predator activity and producer (plant) diversity because changes in nutrient availability often promote competition between different tree seedlings.  Thus, the diversity and location of producers within an ecosystem may be directly related to predator behavior – a relationship that once seemed as unrelated as oil and water.  Now, it’s just another example of interdependence.

Dr. Christine Jurasinski                         LabLearner Staff Scientist

What images does the word “fungi” bring to mind? Well, chances are they’re not images of weathering or erosion. Yet, a recent discovery by researchers in Great Britain has shown that fungi play a significant role in the erosion process.

For years, scientists have known that the roots of plants and trees contribute to the erosion of rock. Ask a 6^th grade LabLearner student about the causes of erosion and weathering of rocks, and tree roots are likely to be one of their answers. However, unlike the answer to “what is a cause,” the answer to “HOW do roots cause erosion” was not known. That is, until recently.

Dr. Bonneville and colleagues from Leeds University in Great Britain set out to answer this question. They investigated the erosion of rocks by plants on a nanoscale. Remember, that the prefix “nano” means one billionth of something, so the events and processes they investigated were not something that could be seen by the human eye or even a compound microscope. When analyzing their results, they used an electron microscope to view changes in rocks. What they found was that fungi on the roots of trees caused the physical and chemical breakdown of rocks, something long hypothesized, but never shown.

So, what exactly happens on the nanoscale when plant roots invade a rock? First, it’s important to remember that almost all plants, including trees, have fungi called mycorrhiza that grow on their roots. Dr. Bonneville and his colleagues created an experiment that modeled this. They obtained a pine tree seedling with mycorrhiza on its roots and placed it in a transparent pot containing nutrient-poor soil and a specific kind of mineral called biotite. Biotite is a mineral commonly found in rock and it is rich in potassium, iron and magnesium. No other fungi or microorganisms were in the soil or on the roots. Then the researchers waited three months. After three months they examined the biotite along a single root using an electron microscope. They found that the biotite at the tip was bent as a result of mechanical pressure from the fungi, a pressure that can reach as high as the pressure in a car tire. This pressure if you think about it, is pretty amazing since the mycorrhiza are microscopic organisms. After performing other tests, they found that the fungi had also chemically altered the biotite, removing its potassium and causing the break-down of the biotite into other soil minerals, vermiculite and ferrihydrate.

Their results suggest that at the nanoscale, tree and plants roots cause erosion of rock through both physical and chemical means. The fungi bend and weaken the crystal structure of rock first and then chemically alter its composition by removing potassium. In addition, the wedging and bending of the biotite’s crystal structure allows other iron compounds in the rock to chemically react with oxygen in the air. In the end, the potassium and other released nutrients are passed onto the roots of the trees or plants and the area around the root that was once rock becomes soil.

For LabLearner students these experiments bridge some of the concepts they learn in the Weathering and Erosion CELL and the Classification GAP Unit. In the Weathering and Erosion CELL, students investigate differences between physical and chemical weathering and erosion of rocks. In doing so, they learn that in nature both types of weathering and erosion occur and that physical weathering and erosion aids chemical weathering and erosion by first breaking down rock into smaller pieces that can be more systemically “attacked” by chemicals. In the Classification GAP Unit, students learn about various multi-cellular organisms, one of which is fungi. They also learn about some properties that are characteristic of fungi, including a symbiotic relationship with other organisms such as plants, and the secretion of enzymes that breakdown matter in their environment.

In the past, students may not have linked the concepts described above together. This latest research, however, illustrates once again that LabLearner students will benefit from exploring all areas of science and hopefully finding new and intriguing connections between them.

Dr. Christine Jurasinski                             LabLearner Staff Scientist

For third, fourth and eighth grade students in the LabLearner Program, learning about charges and circuits means learning about electricity. From electrical power plants to microchips, electricity has been one of the mainstays of our world’s technology and a key component in telecommunication devices. A recent discovery from scientists at Yale University, however, may pave the way for that to change.

Dr. Hong Tang and a team of researchers at Yale University work in a field called nanophotonics. To understand what that means let’s take the word “nanophotonics” apart. Photonics describes technology that uses light to transfer information. Fiber optics, optical scanners, lasers, and satellite imaging are all examples of photonic technologies. What makes ‘nanophotonics” different is that the technological research or applications occur on a much, much smaller scale. “Nano” literally means one billionth of something. For Dr. Tang and his team, their research in nanophotonics deals with silicon microchips. Recently, these scientists made a discovery that may allow silicon microchips and other nanodevices to work using light rather than electricity.

So, why is this exciting news and what may this mean about what LabLearner students learn about electricity?

What’s exciting is that Dr. Tang and his associates discovered a repulsive and attractive force of light. Since about 2005 many scientists have theorized that small beams of light could attract or repel each other when placed very close together- such as on a silicon chip. This attraction or repulsive force was proposed to be similar to the electromagnetic forces that occur between positive and negative charges, a phenomenon that LabLearner students investigate in the Exploring Electricity CELL in third grade and the Electricity and Magnetism CELL in eighth grade.

Now, however, that phenomenon is no longer theory. The researchers at Yale University showed that they can produce a beam of light on a silicon microchip that has a repulsive force and a beam of light that has an attractive force. What’s more they showed that that both beams of light could physically MOVE very small switches called nanoswitches in circuits on the microchip, turning circuits in the microchip on and off.

Does this mean that soon we’ll be able to take flashlights and move objects around? An interesting thought, but no. These newly discovered optical forces are very strong on the nanoscale, but too weak on much larger scales. For example, even focused light such as that found in two laser pointers can’t cause the laser pointers to attract or repel each other.

However, when you think about the type of energy and scale that is involved in something like fiber optic communications, this discovery could be potentially revolutionary. The reason is that many technologies such as fiber-optic communications work by converting light signals into electrical signals and then converting the electrical signals back to light signals, all on a micro and nanoscale. This new discovery suggests that light alone could be used to manipulate signals and move switches. This would make telecommunication and other nanodevices like microchips much, much faster and cheaper.

And what about those LabLearner students? Will this leap in technology make learning about electricity a thing of the past? As with all new technology and with all areas of science, understanding basic principles provides a solid foundation on which to build. Although the repulsive and attractive forces of light are a new and complex discovery, the basic principles of attraction and repulsion remain. These principles are the basis of students’ experiments about static electricity in the third grade CELL Exploring Electricity. In this CELL, students explore what is meant by positive and negative charges, and attraction and repulsion. Through their experiments they see and FEEL a very tangible example of how difference in charges can create at attractive or repulsive force. It is this type of knowledge that sets the stage for understanding what is meant by an attractive or repulsive force of light. As students move into fourth grade they explore energy transformations in the Forms of Energy CELL. Understanding that energy is neither created or destroyed but only changes forms can help students understand the energy transformations of technologies like fiber-optics. Finally as students move into eighth grade and the Electricity and Magnetism CELL, they begin to combine mathematical formulas with tangible evidence of electric and magnetic attractive and repulsive forces. The basic foundation about charges, attraction, repulsion and forces that they build through the LabLearner Program may just lead them to be the designers that harness the attraction and repulsive forces of light in the decades to come.

How Do Sunspots Affect Our Weather?

Dr. Christine Jurasinski                       LabLearner Staff Scientist

Whether you turn on the TV, hit the Internet or open the paper, the changes in the weather during this time of year are making headlines. Hurricanes and tropical storms are developing in the Atlantic and Pacific and the continued dry weather in the Southwest has fueled the wildfires in California.

Now, our ability to predict and prepare for the ramifications of weather events may have just increased. New research by an international group of scientists at the National Center for Atmospheric Research has suggested connections between the 11-year solar cycle, the stratosphere and the tropical Pacific Ocean that may be responsible for changes in global weather patterns. These connections may help scientists better predict the timing and intensity of climatic events such as the Indian monsoon and rainfall in the tropical Pacific.

Scientists have known for centuries that the energy released from the Sun each year varies little. However, over an 11-year period, there is a cyclical difference in the sunspots that erupt from the Sun. As sunspots erupt there is a release of charged particles that alters the magnetic activity and radiation that reaches the Earth. During the 11-year cycle, there is a period at which sunspot activity is at its maximum and a period at which it is at its minimum. This new research suggests a correlation between the maximum period of the 11-year cycle and changes in the equatorial Pacific weather.

The atmosphere of the Earth can be divided into different sections. The troposphere is the section closest to the surface of the Earth. Just above it lies the stratosphere. The stratosphere is heated directly by radiation from the Sun. During the period at which sunspot activity is at its maximum, increases in radiation from sunspots increases the warming of the stratosphere, particularly along the equator where the Sun’s ray are the most direct and intense, something LabLearner students learn in the Solar System and Space CELLs. The result is a more pronounced heating of air around the air in the stratosphere around the equator than “normal.” This change results in changes in stratospheric winds, which can change tropical precipitation, dumping rain in the western equatorial Pacific region. This part of the effect is what researchers are calling the “top down” effect of the sunspots.

For older LabLearner students, another portion of the 11-year solar cycle, the “bottom up” effect, is directly related to concepts they will learn in the Atmosphere CELL and the Clouds and Storms GAP Unit.

As LabLearner students learn in the Atmosphere CELL, radiation from the Sun heats the Earth and its atmosphere. As air is heated, its volume increases. This relationship, called Charles’ Law is one of the key principles students learn in the Atmosphere CELL. This change in volume with heating results in a change in the density of air. The warmer air becomes less dense and rises in the atmosphere. Ultimately it will cool, become less dense and sink back towards the Earth’s surface. This cycle of rising and falling creates global convection currents that affect the climates of different areas on Earth. The rising and falling of different densities of air is also responsible for formation of clouds, precipitation, fronts, hurricanes and tornadoes.

So, how does this recent research fit in with what LabLearner students are discovering through their investigations? The second portion of the new research deals with what is called the “bottom up” effect. The “bottom up” effect is an example of Charles’ Law and the changes that the differences in air density can produce. The increased energy during sunspot maximum also causes a slight warming of the ocean surface waters along the equatorial Pacific (“bottom up” effect). This causes an increase in less dense warm air that rises from the equator and ultimately in more evaporation of water. As a result, there is an increase in the water vapor that is transported by the trade winds to the western tropical Pacific, increasing the amount of precipitation in this region. In addition, the eastern Pacific sees less rain and cooler temperatures because of this movement of air and moisture.

Ultimately, the western tropical Pacific region experiences an increase in heat and rainfall and the eastern tropical Pacific a cooler and dryer year because of both the “top down” effect from stratospheric heating and the “bottom up” effect of ocean water and tropospheric warming. This latest research reinforces what scientists have known and what LabLearner students should discover: that understanding the effects of the Sun’s energy on the Earth is a key to understanding our weather.