Show #25/2012. How Water Works In The Plant World
Water is becoming an ever increasing concern, no matter where we live. In this Episode GardenSMART visits Biosphere2 in Tucson, Arizona to learn about cutting edge research focusing on the use of water in plants.
The 1980's was the 1st time Richard had heard of a Biosphere. Now he has the opportunity to view one up close and personal. Jayne Poynter was one of the original design team members as well as one of the 1st folks to go inside and live. Jayne joins GardenSMART and tells us about the experience. IN THE 80's SHE AND OTHERS WERE DESIGNING THE BIOSPHERE. She was in charge of designing the agriculture. Back then it was rather challenging, they didn't really know how to design a completely organic farm. Now, it's commonplace but then they didn't really know how to make it happen. At least "organic" wasn't mainstream. It was quite challenging, they couldn't use pesticides or fertilizers they instead had to rely on what is called integrated pest management for the crop management and disease control. They took many tips or ideas from really ancient civilizations. In fact they went back to the ancient Chinese because they had really mastered integrated intensive agriculture. Of course they didn't have any of the chemical pesticides and fertilizers we have today. But Jayne and her crew also took advantage of modern agriculture technology, in particular looking at crops that have disease control as well as boosting harvest and boosting yield. It was really a melding of the ancient and the modern technologies.
The original goals were two fold. The first was - can we make a prototype for a space base, something one might see on Mars in decades to come. The second was - can one bottle up life, so that you can learn more about life on earth. This was more than a small ag. station. It bridged the gap between small, highly controlled experiments that one does in the laboratory and large complex, but very uncontrolled experiments that one does in nature. This was right in the middle. It all sounds fascinating, Richard wants to go inside and take a look.
Inside Richard sees what at that time was home. Jayne acknowledges that this was home and an extraordinary experience. She became part of Biosphere in a very literal and visceral sense. It was particularly visible with their food. As she exhaled, the CO2 from her breath became part of the sweet potato, and then when they ate the sweet potatoes, and believe her, they ate an awful lot of sweet potatoes, then the sweet potato became part of her. In fact they ate so many they turned orange. They visibly became part sweet potato and in essence they were eating the same carbon over and over again. Other than turning orange they learned other facts. The crux of the matter was, would Biosphere 2 work for an extended period of time, or would something happen that they could either not understand and they couldn't fix. They did have problems in their 2 year mission. They didn't grow quite enough food and didn't have enough oxygen; which for a life support system is rather disturbing. But the key was they knew what the problem was and they knew how to fix it. After they came out of Biosphere they had experiments in space with very small biospheres that really demonstrated that sealed biospheres work. There are fascinating experiments going on here today. And Travis is the man to explain them all.
Biosphere 2 sits on 40 acres of land, with about 3 acres under glass. As discussed previously it was used for space exploration and space research as well as closed system research. BUT NOW THEY'RE ADDRESSING PLANTS, ENERGY AND WATER. Dr. Travis Huxman is the University of Arizona's director of Biosphere 2. Travis tells us more. Biosphere 2 is an amazing facility. We now know some of it's original history. The building itself cost on the order of $250 million in the 1970's when built but today would cost upwards of $1 billion. Thus nothing like this will be built soon. They feel a real need to aim at big science grand challenges. What they've done is create a research program focused on the problem of water and how water interacts with energy and plant species to create different biomes that we see on the planet, out in the real world. By biomes he means all the different environments they must test and include for all these experiments. Several examples: They have a tropical forest where they control temperature and water in a certain way to allow those different species to grow and thrive. They have a desert where they do something entirely different and directed towards a different type of species. Concentrating on water is important. Whether in here or anywhere in the country or world water is a very scarce resource. The dynamics of water in the world is a scientific grand challenge, understanding where water goes is important. Whether in a natural landscape, thinking about a watershed in some river, whether in an agricultural setting or whether just in someone's back yard focusing on a garden; trying to understand which species might be best suited for those types of environments, all all important questions.
The guys move into the building. Richard comments that this is an incredible place, fascinating. And there is a lot of science going on throughout the entire facility. They visit a lab. Just TRYING TO UNDERSTAND HOW WATER WORKS IN OUR WORLD AND HOW WATER BEHAVES FOR PLANTS IS FASCINATING. To that end they have many instruments that basically measure the behavior of water. A leaf pyrometer is a small chamber that they can put on a leaf that when attached measures the diffusion of water out the bottom side of the leaf. It measures the rate of diffusion. Diffusion means the water coming up through the plant and out the stoma. Or out of the tiny pores that control the water loss from the leaf. This instrument measures how they lose water and how they control water loss. It's a little chamber with humidity sensors along the path link and a surface highly resistant to water loss. The little chamber fills up with water vapor, they measure that rate and that's how they determine the behavior of the stoma. And there are 10's of thousands of stoma on just 1 leaf. They're controlled by the dynamics of water and other things like carbon dioxide. How much carbon dioxide is in the atmosphere? In fact, that's why they use the next instrument which is a little bigger. It's a chamber instrument that measures photosynthesis and water loss. Another machine measures transpiration photosynthesis and controls temperature and light, CO2 concentration itself and it aggregates a bigger part of the plant. But it's still a very microscopic environment. Still at that sort of leaf scale. They also have bigger instruments, like a balance. It's a traditional balance and measures the mass, for example, of a plant in a pot, as that mass changes throughout time, because of loss of water from the whole plant and soil. Science doesn't need to be or use real expensive equipment, this just measures how much water has been lost and measures the weight. But here they do it on a large scale, they have balances about half of the size of this room. They sit on big plots with many different species in different combinations. The next instrument is different looking, it doesn't look like it would be something bought from a scientific instrument company. This piece was home made. It was made by the husband of a PhD student who's a real tecnogeek. It's something they take out in the world, plop it down and push it into the soil. Within the chamber it then measures how much carbon dioxide or water is going in and out of the tiny little eco system. The dome closes, the chamber builds up water vapor concentration or it loses CO2 concentration, because the plants are photosynthesizing. The whole building is really a piece of equipment like this. The same principles utilized in this small piece of equipment are used on the whole 3.1 acres of the building. They go to take a look.
On the way Richard asks if Travis had a Mr. Science kit growing up? How did he get to this point? Travis was inspired by the way he was brought up. His father worked his entire life for the Forest Service, thus he grew up in ranger stations all around the west and saw first hand how people managed the forest. That inspired him to understand why the eco systems worked the way they did and why plants work the way they did, what controlled them. Travis studied ecology and biology throughout most of his college career, then completed his doctorate looking into desert plants, physiological ecology, which is just how do plants work in the real world. Many of the things they did while he was in college they do here, but here they do them on a much grander scale.
The guys arrive in the basement, this is where the inner workings of the building are located. Travis points out one area that has THE BASIC TOOLS THEY USE TO MEASURE CARBON DIOXIDE AND WATER VAPOR EXCHANGES and all the different scales in this big building. There are big tanks that collect water that's percolated through the soils of the biome above. They pump water into the facility, it rains down and lands on the landscape, plants use some of it, some of it moves down through the soils and ends up here. They can then measure how much water vapor they apply in rain and then how much water makes it here, how much water is evaporated out to the atmosphere and lost. Thus, they can close the water budget, they know where all the water molecules go. Every drop.
They also measure the air. What comes in and what comes out, just like those instruments in the lab. They take the whole building, measure the air very carefully that they stream into the building, how much vapor is in it, how much carbon dioxide; then they measure the air going out the other side of the building. The difference between the 2 is photosynthesis and evapotranspiration. When the building was enclosed, thus a sealed environment the atmosphere was in concert with the biomes. The water and aquifer changed in concert with the biomes. That doesn't give one a lot of experimental control because with the air flow-through mode they measure what's coming in and what's going out. They have the ability to assign causation. And they can experiment. Otherwise if everything is in the box you don't really know what's affecting what and what is impacting what.
There is a lot of research going on outside the biosphere, as well. They extend their research themes and questions about water and energy to plant species in the natural world and in this case the built world. THIS IS A GREEN ROOF EXPERIMENT but it doesn't look like a green roof. The purpose of the experiment is to look at the potential benefits of green roofs in a semi-arid environment, like Tucson or Southern Arizona. The control is to see what kind of temperatures one gets on a typical roof. They then want to know what people build with their typical construction materials and how it transmits energy down through the roof and into the house. In this case the term energy and heat are the same. This is about how heat is conducted. They're measuring not only what is going on on the top but looking down and into the area similar to an attic. There are several basins they are in the process of building. They then put soils into the different structures. They want to test different soil types because different soils have different mass, thus would have different benefits on top of a roof. When talking about the mass of soil there is a big difference in weight and how much they weigh when saturated with water. Underneath the soil is typical lining material, a geo-textile fabric. It is put down as an initial barrier to help prevent the soil from going somewhere else in the house. On top of the barrier is maybe a foot of soil. That's the area that plants can easily remove water from. And like many parts of the country, when it rains here, it rains a lot. Thus they must try to capture as much water as possible and not allow it to leave. They need the right soil with the right infiltration rates, the right water holding capabilities and the proper characteristics for plant growth. One of the soil treatments has a lot of organic matter, meaning lots of microbes will grow, thus they expect pretty significant plant growth. The trade off is, it is quite heavy and like a huge sponge. If they were to use sand, the water would move through quicker and there wouldn't be a big change in mass when its wet versus dry. But they can't use just sand or gravel because it wouldn't hold water. There is a trade off between how much water they can store in these soils, the water that's available for plants and the nutrient side that allows plants to grow and proliferate. One station looks just like the sod roof used hundreds of years ago. Here they're planting Bouteloua gracillis Blue gramma, a native plant from Arizona's grasslands. The idea would be this can tolerate the environment and be able to grow without applying extra water. But it will probably go dormant during certain times of the year. So, aesthetically this may not be the most appealing roof, since it certainly is going to turn brown during certain times of the year but it will have pretty good cover on the roof. They will try to compare it to different species. For example, perennials that are evergreen may shade differently, they may be active over longer periods of the year. But then the question is - what soils to put in these stations so that they will have enough water to make it through the dry periods. The grasses when dormant are flammable, the evergreens will not burn. They also have semi-succulents, Hesperaloe. It is something that they know can tolerated this environment well. It handles high temperatures that occur on a roof and it makes fast rain roots. The question is - can they get a dense enough canopy so that one actually gets shading, therefore create the microenvironment wanted on these roofs. This is a great experiment but Richard wonders why it isn't on a roof instead of the middle of a field. Here they're bringing it down to where people can get involved. When this area is complete there will be 36-40 of these little roofs or stations. They will then ask the public to come in and help taking measurements, to get engaged with the scientists on this experiment.
ANOTHER TOPIC OF RESEARCH IS PHENOLOGY. Phenology is the study of the timing of life events in organisms. They study this in plants and in animals. An event might be something like flowering. When do plants flower and what controls those type events. For a human it might be when do people normally have children. Understanding phenology, what controls the timing of different things, is a scientific challenge. People are studying plants all across the country. They're focused on many different things. And that is part of the problem. Every species seems to do things their own way. Here they are studying dominant organisms in the desert but there are people studying many species all across the country. This group is studying the diverse strategy of plants like the Ocotillo which produces leaves after rain events, in a sort of opportunistic way and flowers immediately in the growing season. Other species like Mesquite produce leaves once in a season, then hangs on to them until the end of the year, then drops them. It has 1 big flowering event, not many. Or Cacti, which have an entirely different strategy. Their phenology is all governed around when they might produce fruit and drop their seeds. All of these things are really difficult to understand because they're so driven by environment, they're driven a bit by species as well as biology, thus it's not so easy to tackle these problems. This is something many are focused on. But it is difficult because it is hard collecting enough data to really determine what is controlling the way these plants work to help move the science forward. Importantly, our audience can get involved. The National Phenology Network has just been initiated and it's focused on a couple of things. One it's focused on collecting data from citizens who are observing the natural world, or their gardens or the species that are around them. So, people might walk out every day into their yards, notice what's flowering and what's not, then contribute that data to a national database. There is even an experimental component. We know that if we use the same genotype when we plant that plant all over the country, that's very powerful at helping understanding the biology. As an example, if people across the country were planting a Lilac of the same species, then tracking its progress, that info could be helpful. The same genotype of Lilac planted all across the country in a big matrix, will help understand how environment interacts with those genotypes to give different flowering times, different times of the initiation of the growing season, etc. To get involved click on the link below. Take a look and start collecting data. Building this data set is really a way to advance the science.
Richard asks Travis. You study phenology and water usage in plants and green roofs. How do these things apply to the typical gardener? Travis opines. Many relate plants to their environment and that's the same whether in someone's backyard or in a forest and trying to manage the forest. The end result is we want to change our environment, we want to create a better environment. For gardening it might be creating biological diversity, for your landscape it might be changing the temperature around your house, for the forest it might be changing the way water is processed to our streams. No matter where, individual action can go a long way, a lot of little gardens can add up to a big change in our landscapes. It doesn't matter small or big regardless the part of the country, the principles are the same.
This has been a very different show and experience. Richard has learned a lot. Richard thanks Travis for spending time with us and our audience and for the interesting science lessons.
USA National Phenology Network
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