The environment changes in many ways all at once

The Sonoran Desert in and around Phoenix, AZ is changing in a lot of ways. There is rapid urbanization, thanks to the large and growing population of the Phoenix metropolitan area. That means lots of construction, concrete, invasive species, habitat fragmentation, and all of the other things that come with dense human populations! 

Those humans also drive a lot of cars and burn a lot of fossil fuels. One problem tied to that is the release of nitrogen pollution into the atmosphere, which eventually drops onto the soil. Nitrogen is a nutrient that all organisms need to survive, but too much can start to become a problem. (Just think of carbs in a human diet. We need some, but too much is unhealthy!) That extra nitrogen becomes a form of pollution that can harm the environment.

Also, you probably already know that burning fossil fuels puts excess CO₂ into the atmosphere, which causes our planet’s climate to change. Warmer temperatures is the most publicized impact, but it’s not just about a hotter planet. In fact, in the Sonoran Desert, where the native organisms are already adapted to extreme heat, a couple degrees of warming may not be the hardest part of climate change to deal with. Another part of climate change that could be very important for the Sonoran Desert is the change in rainfall that accompanies the changes in atmospheric air circulation from warmer temperatures. The predictions for this area are that there will be less frequent but bigger rain storms, with overall less rain falling every year. That’s very difficult for plants and animals who are already so water limited in the desert!

A lot of scientists have studied the impact of urbanization, nitrogen pollution, warmer temperatures, or changes in rainfall on ecosystems. But typically they are studied independently, just one change at a time. In the real world, though, these things are happening all at once! The Sonoran Desert organisms don’t get to deal with just urbanization OR warmer temperatures. They have to deal with the pollution, temperatures, rainfall, AND all of the things that come with urbanization, all together. How will they respond?

To answer this question, we set up a lab experiment. It’s hard to separate all of these changes in the field, because they’re already happening! We can study how the soil responds more easily in the lab, where we can turn each of the changes on and off. To do this, we created tiny Sonoran Desert “microcosms” in little vials. They are filled with soil from urban soils inside Phoenix or soils from parks outside the city.

We then created all of the changes that the Sonoran Desert is experiencing. The jars were kept at either regular temperatures, or 2 degrees warmer. Some received nitrogen pollution and some did not. They were given rainfall at either normal amounts and frequency, or larger rainstorms and less frequent rainstorms. We made all of the changes happen at once, to see how the soils responded to each combination of changes.

Here you can see all of the little vials that we were working with. They are in the rack on the bench. We then measured what happened to the soils in response to the experimental changes we made. We measured how much the soil microbial organisms respired, which tells us how active they are. More respiration means the microbes were busier and more active. (That’s just like with you. When you are getting exercise, you breathe heavier and therefore respire more.)

The machine next to the tray of vials is how we measured respiration in each of the vials. We use a syringe to remove the air from the vials, and the machine tells us how much CO₂ was respired by the soil microbes.

While the soil microbes are busy being active and respiring, they are also processing nutrients in the soil. Their activity is how nutrients get recycled and become available for plants to grow. So, we also measured the nutrients in the soil inside our vials.

We learned that all of these types of environmental changes influence soil microbial activity in some way. Soil microbes respire more in urban soils and when there is extra nitrogen from air pollution, which means the carbon stored in the soil can be released. That’s more CO₂ going into the atmosphere! Different amounts and frequencies of rain also resulted in different amounts of soil activity. So, all of these human activities will change Sonoran Desert soils!

But, importantly, we learned that when you make multiple changes at once (like add nitrogen pollution AND change the rainfall at the same time), the response from the soil microbes is not the same as what you would expect from studies that only look at one change at a time. When it “rained” in larger amounts but less frequently, the soil microbes responded much more when there was also extra nitrogen from air pollution. So, not only do we know that humans are changing soil activity in the Sonoran Desert, but we also learned we need more studies that look at these changes all at once!

The results of this study are published in: Williamson, M., B.A. Ball. 2023. Soil biogeochemical responses to multiple co-occurring forms of human-induced environmental change. Oecologia 201: 1109-1121. doi: 10.1007/s00442-023-05360-7

How will soil invertebrates respond to climate change? Ask the plants!

Climate has been changing on this planet, and will continue to change. We hear a lot about warmer temperatures, but that's just one piece of the story. Another important part of climate is also changing, and that's precipitation.

Here in the Sonoran Desert, we get rain during two different seasons: during winter and during our summer monsoons. With climate change, we are seeing our precipitation change. One prediction for the future of the southwestern U.S. is that we will get rain less frequently, but when it does rain, the storms will be larger. How will less frequent precipitation influence the ecosystem? Even though the rain that comes may deliver more rain at once, a lot of that extra rain can't be absorbed into the soil. So that might mean less water available overall for the organisms.

Certainly the plants will respond to that change. If they can't rely on receiving water as frequently as they're used to, it's harder for some plants to survive. A lot of studies have looked into plant responses to changing precipitation patterns. In our research group, we like to learn about the soil community that support the plants: the microbes and invertebrates that recycle nutrients so that the rest of the ecosystem can thrive! How will they respond to changes in precipitation? Much less is known about that!

Soil invertebrates include organisms like this velvet mite.

So we did an experiment to find out! In the Sonoran Desert, we spent one monsoon season changing the timing and size of rainfall and measured how the soil community responded. We used watering cans to make "fake" rainfall events. 

We watered the soil using either the normal pattern for precipitation during monsoon season (as our control treatment) or with changes to the frequency and size of the storm. Some of our plots received rain at the same size of storm but less frequently. Other plots received rain at the same frequency but with larger amounts of rain. Then other plots received rain in what is predicted for the future: less frequently but with larger amounts.

We then took soil samples and extracted the soil invertebrates so that we could see how they changed in response to the experimental rain. We predicted that the communities would become less abundant and diverse if they received rain less frequently. But we had another question: Do plants help protect the invertebrate community from changes in rainfall? Plants provide shelter for the soil beneath them, providing shade, pulling water towards the surface of the soil, and creating food for the soil organisms. If plants are present, does that mean the invertebrates don't feel the impact of precipitation as much? 

So we did our experimental rainfall experiment in soils directly beneath plants and compared that to the rainfall experiment on bare soil, Here, Kelly is "making it rain" beneath a creosote bush. 

We also wanted to know whether type of plant matters. Creosote bush is a larger shrub that has deep roots and keeps its leaves all year round. We also did the experiment under a different type of shrub. Bursage is a smaller shrub that goes dormant during periods of drought. They drop their leaves, stop photosynthesizing (so stop bringing up water). That means that a bursage in spring might look like this:

But during periods of drought (like a hot, dry summer!) might look like this:

That creates a very different habitat for soil organisms than a big, evergreen creosote bush! So we "made it rain" with either less frequent or larger rainfall events (or both!) under creosotes, bursage, and bare soil over the course of one monsoon season.

We collected soil at the start of the experiment to look at initial differences between creosotes, bursage, and bare soil. Then we collected soil again at the end of the experiment to see how soil communities responded to the change in precipitation. We predicted that we would see more change in the bare soils compared to soils beneath plants, because we expected the plants to help protect the invertebrates from the lack of water we created.

In the lab, we extracted the soil invertebrates from the soils. Then, we used microscopes to look at the invertebrates, so that we could identify and count them. A LOT of students helped us with the microscope work!

From the results, we learned that plants have a big influence on the soil invertebrates. The community of invertebrates living beneath creosote and bursage plants is much bigger and more diverse. The invertebrates must really like having the shade and resources from a plant above them! Both creosotes and bursage housed larger communities, but creosotes had the strongest effect. The invertebrates really like the shade and resources from deeper rooted plants that are active during monsoon season!

Changing precipitation didn't have a big influence over how many invertebrates lived in the soil, but it did change the diversity of the invertebrates. There are many different ways to count "diversity", and two of these measures were influenced by changing rainfall (Shannon diversity index and evenness). Making rain fall less frequently reduced the diversity of invertebrates in the soil. However, as we predicted, the communities beneath plants were less effected than in the bare soil. Soil invertebrates living away from plants are exposed to the changes in precipitation, but they are more protected when they have the help of a plant. That means that if the abundance of plants like creosote and bursage change in response to the climate, the soil invertebrate community will change. And those invertebrates do a lot of important processes for nutrient recycling and decomposition in soil, so there can be major consequences for the overall ecosystem!

The results of this study are published in: Ball, B.A., K. Bergin, A. Morrison. 2023. Vegetation influences desert soil arthropods and their response to altered precipitation. Journal of Arid Environments 208: 104873. DOI:10.1016/j.jaridenv.2022.104873

Urban forestry... in the desert?

Cities, like Phoenix, burn a lot of fossil fuels and release a lot of CO₂ into the atmosphere. Think of all of the cars on the road, houses using electricity, and businesses and industries that use fossil fuels, too! The CO₂ is a greenhouse gas that influences the climate of the entire planet. How can cities reduce how much CO₂ is released into the atmosphere? One way is to burn less fossil fuels. We try this through efforts like increasing cars' fuel efficiency and switching to solar power. Another way is to try to re-absorb the CO₂ that was put into the atmosphere. So, even though the fossil fuels are being burned and CO₂ is going into the atmosphere, we can try to pull some of it back into the city so that it doesn't stay in the atmosphere. This lets cities "mitigate" the amount of CO₂ they create.

There are a lot of scientists who are trying to engineer fancy new technology to absorb CO₂ from the atmosphere. But there is also a simple way that just uses nature: trees! Trees pull a lot of CO₂ from the atmosphere when they photosynthesize, and they hold onto that carbon for a long time. Trees live for decades or more, which means the CO₂ stays in their biomass for decades. ("Biomass" is the scientific term for the entire mass of the plant, and about half of that biomass is made up of carbon!) Every year they shed parts of their biomass, like leaves and twigs, onto the ground, which gets decomposed and turned into "soil organic matter". That soil organic matter can become very stable in the soil, meaning it only continues decomposing VERY slowly. The soil organic matter builds up over time in the soil as trees shed their leaves, bark, and twigs, locking it into the soil instead of the atmosphere. So, not only do trees hold a lot of carbon, they also build up carbon in the soil where it can be stored for hundreds of years.

The carbon cycle in an urban forest ecosystem: The trees take up CO₂ through photosynthesis, and that carbon is stored in the tree for decades or more. When the tree sheds its dead parts (called "litterfall"), it decomposes in the soil, creating a form of soil organic matter called "humus". The humus can slowly decompose, which will release some of the carbon back to the atmosphere through respiration, but it is VERY SLOW. More litterfall every year creates humus faster than it is decomposed, which means there's a buildup of humus over the years, storing carbon in the soil for centuries!

Growing trees is easy in a lot of cities and has other benefits, like providing shade, cooling the surrounding area thanks to transpiration, making a home for birds and other animals, and generally looking pretty! "Urban forestry" is becoming popular in some cities. But... we live in a desert! Can Phoenix use urban forestry as a way to mitigate our CO₂ emissions? Many trees that have been planted in yards and along streets aren't native to the desert, so they require a lot of extra water to survive. That creates its own problems! Is there a way that Phoenix can grow native trees without having to give them a lot of irrigation? Can urban forestry be a sustainable way to capture CO₂ in a desert city?

That's what Arizona State University is trying to find out. We have planted an "urban forest" on campus, using only native trees that are good at surviving in a desert climate (without needing to be watered every day). The forest was planted in an unused area of the West Campus where some mesquite trees had "volunteered" to grow. But, most of the area was bare. One thousand mesquite and palo verde saplings were planted into those bare areas!

This is the area of campus, just before the forest of saplings was planted.

1,000 mesquite and palo verde saplings were planted into the bare areas to grow into a forest.

Right now, the trees are little saplings. As they grow, they will capture CO₂ during photosynthesis and store it in the tree biomass, and as they shed their leaves and wood, they will start to build up the carbon stored in the soil, too. However, they grow slowly, especially since we're only giving them water early in their life until they establish. After that, they are on their own to find water! 

So, how much carbon can a slow-growing desert forest absorb? We will be measuring that every year. We are measuring the growth of the trees, to estimate how much carbon is being stored in the tree biomass. We are also measuring how much carbon is being stored in the soil. The trees and soil are the two main places we expect to see the carbon stored.

One of the saplings whose biomass we measure every year. Hopefully we will see its biomass increase year-after-year, meaning it has removed CO₂ from the atmosphere and stored that carbon in the plant.

We are also making other measurements, to better understand the carbon cycling in the forest. We are measuring processes like photosynthesis and respiration rates (where CO₂ is moved between the forest and the atmosphere), the amount of "litterfall" every year, and the biomass of microbes living in the soil who do the respiration.

Kevin measures soil respiration using an infrared gas analyzer.

David measuring microbial biomass living in the soil using a process called "chloroform fumigation extraction".

It will take a long time before we have results from our experiment, because the trees grow slowly. If it is successful, it will grow into a beautiful mesquite bosque that not only stores carbon, but also provides shade, a habitat for birds, and a food source for pollinators. It will take decades to reach maturity! Until then, we will keep making our measurements every year, as we (hopefully) watch the trees grow.

When your study organism fights back...

I explained back in this previous post about how important decomposition is for an ecosystem. Without the recycling of dead plants through decomposition, new plants wouldn't have enough nutrients to grow! It's such an important process that scientists have been studying it for decades. We want to understand what determines the speed of decomposition, and the way that the nutrients are recycled.

Of course, decomposition in the desert can be very different from other ecosystems, because it is very dry and hot, so biological processes (like decomposition) can be much slower. Another reason that desert decomposition can be different is that we have a lot of unique plants that become that "plant litter" that decomposes. Our plants are well-defended against herbivores, which means they are also (often accidentally) well-defended against decomposers! Decomposition studies don't often look at those unique plants. For example, there are only very few studies that have measured cactus decomposition. Even though cacti are an incredibly abundant plant in the Sonoran Desert, we don't know much about their life-after-death role in the ecosystem!

Students in my lab got curious about cactus decomposition, so we set up an experiment. 

Miranda and Ephraim building cactus decomposition cages.

The normal way to study decomposition is using litterbags, like I showed you here. But that's hard to do with a whole piece of cactus, because of the spines that stick out! It's hard to bag a plant that fights back! Ouch! So we built "cages" on the ground made out of the same material that is used for litterbags. These cages trap the cactus in place, so that we can refind each piece to measure its decomposition.

We put two different species of cactus into the cages. Both species are common in the Sonoran Desert. Prickly pear cacti have big, flat segments (called "clades") with large spines but are very juicy inside. Cholla clades are hard and cylindrical, and while they still have soft insides, they have a thicker skin on the outside that might make it hard for decomposers to eat through. So we hypothesized that these two species would decompose at different rates, and release different amounts of nutrients.

The big, flag cactus in the cages on the left are prickly pear, and the skinny, round cactus in the right-side cages are cholla.

Once our fresh cacti were in their cages, we let them decompose for a year. They went from looking like this at the beginning of the experiment...

The holes in these prickly pear clades are from cores that we used to measure their chemical properties at the start of the experiment.

...to this one year later!

Over the course of the year, we collected some of the cacti every few months so that we could track how much mass and nutrients had been released during decomposition. So, every few months, we brought the cacti back into the lab to measure their weight and chemistry:

Guillermo, Coby, and Chase breaking apart a decomposing cholla clade to measure its chemistry.

What did we learn about cactus decomposition? We learned that decomposing cacti recycle nutrients just as well as leaves from deciduous shrubs and trees. We also noticed that cacti recycle a LOT of calcium, way more than other types of plants (almost 10 times as much as other leafy plants!). That's because cacti have a lot of compounds called "calcium oxalates", which means there's a lot of calcium stored in their clades to be recycled when they die. 

We also learned that, despite the differences between prickly pear and cholla, their decomposition is pretty much the same... at least over the first year that we investigated in this study. There are a few differences between the species, though. Prickly pear released more water than cholla, and it also released potassium (an important nutrient for new plants!) faster.

There is still a LOT left to learn about cactus decomposition. We only looked at two species in one desert site, which is just a "drop in the bucket" for understanding how important cacti are in desert ecosystems. But what we do know is that cacti have an important role in nutrient recycling, so it is worth learning more about it!

The results of this study are published in: Bilderback, A.H., A.J. Torres, M. Vega, B. Ball. 2021. The structural and nutrient chemistry during early-stage decomposition and desiccation of in the Sonoran Desert. Journal of Arid Environments. 195: 104636. DOI:10.1016/j.jaridenv.2021.104636

Sonoran Desert BioArt

Last year I told you about our course in BioArt. Students work in teams to conduct research in the Sonoran Desert, and they communicate that research through a creative work of art. In the Spring semester of 2021, we had another great group of students work on projects in this course, creating wonderful works of Sonoran Desert art!

Anastasia and Rachael studied the role of desert vertebrates in the spread of cholla, a common cactus species in the Sonoran Desert. Cholla spreads to new habitats by dropping segments of the plant (called "tubercles") that can take root in the soil where they land. These tubercles are covered in hooked spines that work like velcro: they catch on the fur of coyotes, rabbits, and other mammals to be carried around and dropped somewhere new, away from the parent plant. So these animals are important to help spread this cactus, but humans are changing the abundance of these animals! How will urbanization impact the spread of this desert plant species? Anastasia and Rachael used camera traps and other survey techniques to learn which animals were associated with cholla plants. They learned that coyotes, deer, rabbits, and packrats were active in the area around chollas in the Sonoran Desert. Learn more about it in their research poster.

To demonstrate the action of a tubercle being removed from the cactus and spread to new habitats, Anastasia and Rachael created a soundscape video and an interactive cactus model. You can play the video to hear the sound of a tubercle being ripped from the cactus as it would be by a passing desert mammal. Tubercles stick to mammalian pelts because of tiny barbs on the cactus arms, ripping the tubercle off the main body like Velcro is ripped apart. This is the reasoning behind creating the interactive cactus model – arms are attached to the cactus body via Velcro, so viewers can experience the sensation of ripping a cactus arm off the main body. 

Joe and Mikayla explored whether the number of arms on saguaro cacti are related to water availability. Scientists don't actually know what signals saguaros to grow their iconic arms. We know it doesn't happen until they are older, and some saguaros don't grow arms at all! One hypothesis is that the arms are for extra water storage, in which case the number of arms would relate to water availability. Mikayla and Joe measured soil moisture along gradients from sources of water, and counted the number of arms on the saguaros at those locations. They did not find a relationship between soil water (or distance from the source of water) on the number of arms on the saguaros growing there. So... the reason for saguaros to grow arms remains a mystery! Learn more about it in their research poster.

To communicate their research, they created a glass tile mosaic that highlights the impact water availability has on Saguaro cactus branching. The recycled glasses contain blue marbles, representing the availability of water to each mosaic Saguaro it sits below. Both glasses contain the same amount of marbles, due to the research determining no significant difference between the water available to a Saguaro and its number of branches. This beautiful mosaic also sheds light on the complexity of Saguaro growth and the need for more research in this area. 

Jared and Irvin designed a rain garden that can maximize plant productivity with efficient water use in the Sonoran Desert. Rain gardens are a common form of "urban agriculture" that rely on rainwater to survive, but is that actually feasible in a desert city that doesn't receive a lot of rain? They used an infrared gas analyzer to measure the water use efficiency of native desert plants, and used their results to select the best plants to include in their design for a Sonoran Desert rain garden. Learn more about it in their research poster.

Irvin and Jared then designed the landscape for the garden using these efficient native plants, focusing on those that have tangible benefits to the community (like being a source of food or fiber for people). Of course one semester is not enough time to actually construct an entire garden, but in their blueprint, they designed it to contain artistic elements that would make it beautiful for visitors. The garden consists of three terraces: the ground level, level two at 2’ down, and level three at 3’ down. The blueprint features natural colors from the biotic elements with highlights of the pink milkweed flower and purple fruit from prickly pear. The abiotic elements are made to match the Sonoran Desert aesthetic. 

Nitrogen pollution in the urban Sonoran Desert

 Phoenix is one of the fastest growing cities in the United States. That means a LOT of people live in the city, which means a lot of fossil fuels are consumed. When we think about the environmental impacts of fossil fuels, we usually hear about carbon dioxide (which is a greenhouse gas and contributes to global warming and climate change). But that's not the only down-side to fossil fuels. Another form of pollution caused by burning fossil fuels is "nitrogen deposition". 

When fossil fuels are combusted in, for example, a car engine, nitrogen compounds are released into the air. While these compounds are in the air, they go through chemical reactions and eventually fall back to the ground. This is one of the components of "acid rain", which you've probably heard of before. But here in the Sonoran Desert, it's a bit different. We don't have a lot of rain. So sometimes the nitrogen comes down in the rain, but sometimes it comes down in dry particles, kind of like dust. That's why we call it "nitrogen deposition". Deposition just means everything coming back down to the ground - it can be either wet (like rain or snow) or dry (like dust).

We know that the Sonoran Desert is receiving extra nitrogen deposition around Phoenix. How do we know? We measure it! Our research group (CAP-LTER) has many research sites inside and outside of Phoenix where we measure how much nitrogen is coming down to the ground. We use what we call "deposition collectors", which are a group of funnels that catch the dust and rain. Filters connected to the bottom of the funnels collect all of the nitrogen compounds that came as part of the dust and rain. The filters get collected on a regular basis for measurement.

You can watch this video where our Site Manager, Quincy, shows you the "deposition collectors" and how he gathers the filters for measurement:

From these "deposition collectors", we know that the desert areas inside the Phoenix urban area are receiving more nitrogen than outside the city. The large population of Phoenix is having an impact on how much nitrogen is in the Sonoran Desert! Not only do we measure how much nitrogen is coming down, but we also measure how that nitrogen influences in the Sonoran Desert plants and soil.

Nitrogen is a nutrient that all organisms need, but it becomes a problem when there's too much of it. (You CAN have too much of a good thing!) Nitrogen can become toxic in high concentrations and kill the organisms living in the soil. It can even make humans sick if it gets into the groundwater! Plus, adding a lot of nitrogen can upset the balance for the ecosystem. (For example, you can read here how excess nitrogen causes problems at some national parks.)

Our research group (the CAP-LTER) has been measuring the impacts of that nitrogen pollution since 2006. The nickname we give that experiment is "DesFert", which is short for "Desert Fertilization Experiment". CAP-LTER has been following the excess nitrogen in the plants and soils to see how the Sonoran Desert changes with these extra nutrients. We also experimentally add extra fertilizer to our research plots to predict how the Sonoran Desert will continue to change if the pollution continues.

If you want to see what the research plots look like, and learn a little bit about the actual measurements we make, you can watch this video:

BioArt in the Sonoran Desert

BioArt: Sonoran and Arctic Environments is an interdisciplinary course at Arizona State University’s West Campus that pairs science and art majors to conduct independent scientific research and science communication through art. While the disciplines of science and art are usually considered to be very different, they actually require a similar set of skills: observation, interpretation, creativity, and communication. Students in this course hone these skills by studying both art and science in two ecosystems that are also considered to be very different, yet in fact similar in many ways: the Sonoran Desert and the Arctic. The goal is to train a broader group of students in both disciplines and engage them in science communication.

The product of these scientist-artist teams gets displayed in an exhibition, including the traditional scientific presentation of their research, as well as the creative work that conveys the research through a different medium. The most recent set of projects was exhibited in August & September 2019 at the Fletcher Library at ASU. This spring, the work was set up for display at the South Mountain Environmental Education Center, to be enjoyed by visitors to South Mountain Park. That way, visitors to this Sonoran Desert reserve could see science and art based on that ecosystem! Unfortunately, that display was cut very short. It was up for only one weekend before the visitor center was closed due to the COVID-19 pandemic! Since it can no longer be enjoyed by in person, I thought I could perhaps publish it here, for people to enjoy remotely all over the world.

So, without further ado, I present to you the BioArt projects from the Sonoran Desert!

Lourdes, Mohammad, and Rebecca explored how different amounts of precipitation can influence the abundance and diversity of wildflowers in the Sonoran Desert. They learned that different locations have different wildflower communities, though humans may have a role in creating those communities, not just precipitation alone. Learn more about it in their research poster.

This trio of canvases represents how rainfall can influence heterogeneity of wildflower communities around Phoenix. The blue paint at the bottom of the canvas represents how many centimeters of rain fell from December 31st, 2018 through March 1st, 2019 at three different locations in the Phoenix area. Our goal is to show which species of wildflowers were most common at each site that was surveyed. The most common species of wildflowers were centered around the least common wildflower species.

Paul & Shauny's experiment investigated the amount of excess nutrients can be found in lakes next to recreation areas that use different amounts of fertilizers, and whether that makes algal blooms likely in those areas. They found more algae in lakes near fertilized areas, with the amount of nutrients depending upon the management practices used.  Read more in their research poster.

Essential nutrients include nitrogen (N), phosphorus (P), and potassium (K) to nourish and sustain life in both terrestrial and aquatic environments when present in properly balanced quantities. An imbalance in nutrient levels, such as that caused by the addition of fertilizer to a terrestrial ecosystem which runs off into a nearby waterway, can cause a rapid spike in primary production, depleting resources and ultimately leading to the death of organisms within the system. In their artwork, an unsuspecting abundance of ciliates, flagellates, and multiple algae species swim on shimmering silver stream currents as they feast on an unexpected influx of NPK, the result of fertilizer run-off from a nearby field. Just like phytoplankton, this painting requires light to be vibrant. (Unfortunately, I took this photo at night, so you can't see the light reflection that makes it shimmer!)

Brittany and Kamber investigated how soil fertility changes as you increase in elevation up mountains in Phoenix's park reserves. They found that some nutrients increase with elevation, while others decrease. Read more in their research poster.

Their short film is a visual and auditory representation of the Sonoran Desert and some of the many species of organisms that inhabit it. All photography and videography is original work inspired by our driving question of: “Does human interaction in the Sonoran Desert affect overall soil fertility?” Although experimentation heavily relied on test tubes and various lab work, immersing ourselves in the environment of interest and sharing these experiences through photographs and video has helped support our findings. Yes, human interaction in the Sonoran Desert affects overall soil fertility. We are striving to help others understand that even something as basic as “dirt” is actually nutritionally complex soil in need of our protection. Through both art and science, we can make the world a better place. You can watch their video here:

(Like BioArt and want to see a few examples from the Arctic, as well? See our sister Polar Soils Blog at this post, as well as this post.)