Students in Los Angeles Use Science to Design a Better Playground

By Lily Reynolds

What would playgrounds look like if preschoolers designed them? At a school in northeast Los Angeles, students are creating their own playground using outdoor science education. The “Afterschool Schoolyard Design Club” is led by parent Anupama Mann who is a designer and architect. Mann and students at Rockdale Elementary meet afterschool to enhance their existing playground in a hot, dry climate. Last year students started identifying goals for their playground, and a top priority was shaded play areas. The Club wanted to find out which trees would provide the most benefits and have the best chance of thriving in a region experiencing extreme drought.

Students of Rockdale Elementary School meet for the Afterschool Schoolyard Design Club.
Students of Rockdale Elementary School meet for the Afterschool Schoolyard Design Club. (Photo: Anupama Mann)

The “Afterschool Schoolyard Design Club” is one of four Earthwatch Institute Micro-grant awardees for 2016. The Micro-grant program set out to find – and fund – new lesson plans that would teach students about trees, urban resiliency, and climate change.  Earthwatch created the Micro-grant to support students’ engagement with nature because it is an increasingly rare but super important part of childhood development and learning. Earthwatch Institute has found that educators have a strong appetite for citizen science activities, but they need to tie it back to the curriculum they are teaching. Therefore, the Micro-grant requires classroom techniques that involve hands-on activities and meet state standards.

By making observations in the schoolyard, students learn new science concepts and employ problem solving in the field.
By making observations in the schoolyard, students learn new science concepts and employ problem solving in the field. (Photo: Anupama Mann)

For the Rockdale Elementary Afterschool Schoolyard Design Club, the Earthwatch Institute Micro-grant is funding a series of activities to “identify the trees that we would like to plant on the site by studying their morphology, placement on the site, growth patterns, shade patterns, coexisting plants and organisms”, says Mann. Using the playground as their laboratory, the curriculum aims to “get children interested in how trees can play a role in in improving existing asphalt school grounds, providing shade, fruits and flowers, attracting wildlife and birds”.

Back in the classroom, students take what they’ve observed about tree species attributes and make drawings and models.
Back in the classroom, students take what they’ve observed about tree species attributes and make drawings and models. (Photo: Anupama Mann)

One of the first tasks for club members is to observe trees on school grounds “as a way for them to understand trees suitable to the climate they are in, seasonal changes and how an increase in the tree cover impacts the microclimate and microclimate”. The students will gather data to understand the placement of the trees on the existing asphalt playground depending on their suitability to how the area around and below is going to be used.

The final built model will be a visual and physical resource for the entire school.
The final built model will be a visual and physical resource for the entire school. (Photo: Anupama Mann)

By investing in the development of curricula, Earthwatch Institute is making it easier for teachers and after school leaders to bring their students outdoors to do science. Over the next few months, look for more blog entries about Rockdale Elementary students and other Micro-grant awardees in the LA region. Ultimately, Earthwatch is hoping the approaches educators are using in their new curricula can be shared with other schools.

Students working together on the urban tree design for their playground.
Students working together on the urban tree design for their playground. (Photo: Anupama Mann)

Please send any examples or ideas for how we can work with schools and students on planting the right tree in the right place.  Also, share your ideas with us about how best Earthwatch Institute can disseminate these results and continue to support teachers and students in the LA region in science education and urban forestry.

Earthwatch Institute is helping classrooms discover how diversity of trees can be a way to harness nature’s resiliency.

Functional Diversity of Trees in Urban Settings

By Julie Ripplinger, PhD, Postdoctoral Researcher

Ripplinger_photo

I am a Postdoctoral Researcher at University California-Riverside in the Jenerette Lab studying urban biodiversity and human outcomes. My research interests include traditional ecological research and the effects of human activities on ecological dynamics. Before working at UCR, I did my PhD at Arizona State University on how people’s decisions under a variety of pressures (like droughts, recession, and peer pressure) can change biodiversity patterns in cities. I have also studied the effects of historic legacies and land use on tropical dry forests and sagebrush steppe ecological communities.

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Conceptual framework for my PhD research. Urban plant biodiversity is a product of biophysical processes (e.g. climate, substrate, biotic interactions), disturbance (e.g. biophysical and socioeconomic), and human management.

Now working at UCR, my research with Earthwatch Institute builds on my previous research and focuses on the functional diversity of trees in urban settings. I am pleased to say that I’m standing on the shoulders of countless citizen scientists who spent their precious volunteer time measuring tree traits and collecting leaf samples in the greater Los Angeles region. And I have my University of California-Riverside predecessors to thank for this opportunity, because they had the foresight to spark a collaboration with Earthwatch and NASA.

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A relatively simple idea lies at the core of this study – that cities provide a different environment for trees than they’d experience in their native habitat, and just like in non-urban ecosystems, we expect those differences to be detectable in characteristics of urban trees. I am focusing specifically on leaf characteristics that are known to be tied to the environment a tree is growing in. For this study we are testing our idea by comparing certain measurable characteristics of several tree species found throughout the greater LA metropolitan region across a gradient of climate and urbanization. For this part of the collaboration, Earthwatch citizen scientists surveyed trees from parks near the coast all the way out to the desert parks around Palm Springs, encompassing 105 distinct tree species at 61 city and regional parks.

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Earthwatch citizen scientists located, measured, and collected leaf samples from hundreds of trees throughout the greater Los Angeles region. These trees spanned from the Coastal Zone near Long Beach, thru the Central Zone and Inland Empire, and out to the Desert Zone near Palm Springs. What a monumental effort!

By measuring leaf characteristics like specific leaf area and nitrogen per leaf mass (leaf N) content, we will begin to understand how urban forests are functioning and the role that climate and urbanization play. Specific leaf area (SLA) is the ratio of leaf area to dry leaf mass, and it tells us how quickly a tree is growing and its photosynthetic rates. A slow-growing tree will have thicker leaves and lower SLA than a tree that’s growing quickly. A quick-growing tree will have thin leaves with a large amount of leaf N — signs of its high photosynthetic ability. So, measuring leaf N tells us even more about a tree’s growth strategies and photosynthetic abilities. As a general rule, photosynthesis rates decrease linearly with leaf N and increase linearly with SLA.

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Leaf characteristics are affected by many things, including the environment the tree is growing in.

Our preliminary results show that urban trees are responding to the climate gradient similarly to what we’d expect, but not exactly so. For the most part, specific leaf area is decreasing from the Coastal zone to the Desert zone, but the Central zone actually has the highest SLA on average. So photosynthetic rates decrease as we move from the coast to the desert, but why is it higher in the central zone than along the coast? One of the things we’ll be looking at in the near future is how that differs by species. If you think about it, the different tree species in cities come from all over the world, and likely adapted to wetter or drier or hot or cold climates, so we’d expect the different species to behave differently from each other as they respond to their urban setting. These differences reflect climate filtering like an inability to tolerate freezing or the filtering of human decisions about how much they’re willing or able to water trees in park landscapes, and they will be the focus of this study as it progresses. The variations in climate and in tree management activities allows many species to persist in the greater Los Angeles region, and I will be exploring this and other related ideas with my Earthwatch and UC Riverside collaborators as these projects progress. Feel free to contact me at the Jenerette Lab if you have any questions!

Not all trees are created equal: a review of the latest scientific research

falltreeExtreme weather, like “extreme” sports is something best avoided unless one is prepared and willing to live on the edge. Yet, cities around the world are trying to prepare for the effects of extreme weather. The urban environment of the future promises to be hotter, drier, and be marked by more extreme weather events.  One promising adaptation strategy for cities is increasing the number of healthy trees.  Cities that plant and grow more trees stand to gain resilience in the face of climate change.

The beneficial ‘services’ that trees provide our cities include: cooling our homes and buildings with shade, filtering storm water, capturing carbon we produce, and also beautifying our neighborhoods.  However, not all trees are created equal and each species may be better suited for different urban environments and climates.

Southern California is an especially interesting region for climate change research because the metropolitan areas span three ecosystem types and it’s the second largest metropolitan area in the United States.  Because trees in urbanized centers such as greater Los Angeles are planted by the people who live there, it is important to get inside the psyche of residents to figure out why they choose to plant certain tree species instead of others.

A team of scientists led by Meghan Avolio and including Darrel Jenerette from University California Riverside studied the Los Angeles region with one particular question in mind; what drives peoples’ preferences for different species and how do these preferences align with the benefits offered by different tree species.  For example, would people living in hottest parts of Los Angeles be more likely to choose trees that offer shade?  The researchers also were interested in whether things like people’s age, gender, and income are related to their preferences of tree types. (See the full article here.)

Image from The Giving Tree by Shel Silverstein
Do you really know why you love that tree?  (Image from The Giving Tree by Shel Silverstein)

The researchers analyzed 1,029 household surveys across Riverside, Orange and Los Angeles counties.  The two most important attributes of trees that people consistently valued were whether trees provided shade and provided showy flowers (i.e. beauty). The scientists also found people living in hotter parts of Los Angeles (away from the coast) were more likely to value shade trees than those located in cooler regions.  Moreover, people living in drier regions were more concerned about tree water use than people living in areas with higher rainfall. Interestingly, whether the local environment was naturally treed or not also had an effect on people’s perceptions of the value of trees. People that were surrounded by desert were less likely to identify positive effects of trees in urban environments compared with people located in naturally forested areas. Several factors such as levels of education, wealth, gender and age all influenced people’s perceptions of trees.  For example, older residents were more likely to be concerned with the cost of maintenance and women were more likely to associate trees with positive attributes in urban environments than men.

Thanks to this study, for the first time we understand that both the climate where people live and their socioeconomic attributes affect their opinions of different tree characteristics.   Moreover, when combined with another study led by Avolio and her collaborators (see link), we know that people’s preferences for trees often coincides with the trees in their yards.  For example, people who identify shade trees as important live in neighborhoods with greater proportion of shade trees. However, this is not true for all socio-economic groups. While people from lower income neighborhoods have strong preferences for fruit-bearing trees, this preference does not translate into more fruit-bearing trees in their neighborhoods. This may be due to the restricted economics of this group that prevents them enacting their preference.

Avolio and her collaborators have shown how people are sensitive to what is happening in the environment where they live.  This is a good sign when it comes to the future of urban forests, because it means that people consider tree attributes in the context of their neighborhood when planting trees.

Major metropolitan regions such as Los Angeles need to prepare for climate change and planting trees is one good strategy.  Research like this can help managers and planners in cities like Los Angeles make better decisions about which trees need to be planted in each neighborhood to help adapt to a drier and hotter future.

“Understanding preferences for tree attributes: the relative effect of socio-economic and local environmental factors” by Avolio, M. et al., was published in Urban Ecosystems, March 2015, Vol 18 Iss 1 pp 73-86.

Tolerance or Avoidance? How trees respond to hotter, drier climates in Los Angeles

By Peter Ibsen, PhD Student, Jenerette lab at UC Riverside

While humans around the world are preparing for the effects of climate change, plants will also need to respond for extreme heat and drought conditions.  Understanding how plants are adapted or not to extreme conditions may help us humans learn how we can use plants to cope with a hotter and drier future.  Especially in cities, where temperatures are usually hotter and plants are less common, we need to know which plants are best prepared for climate change and how we can use them to build more resilient cities.

Peter Ibsen, scientist in the Jenerette lab at UC Riverside
Peter Ibsen, scientist in the Jenerette lab at UC Riverside

But studying plants across such a large and varied landscape would be a challenge for even the largest and best resourced research groups. Thankfully, we have been working with the help of citizen scientists (i.e. people such as you, the general public), to find and collect essential data of the large variety of tree species across this region – and we are beginning to start to understand how plants will cope, or not with extreme conditions.

As a scientist in the Jenerette lab at UC Riverside, I study the unique environment of urban Southern California. Having worked as a landscaper and nurseryperson for seven years in the Bay Area before I re-entered academia, I have a strong connection to the vegetative ecology of cities.

What makes this environment so unique? The Los Angeles Metro region is one of the most biodiverse urban places on Earth. It contains over 500 different tree species, representing nearly every region on the planet resulting in a global example of multiple evolutionary processes (found in growth rates, rooting structures, water usage, leaf shape and tree size), and it is right in our backyard!

Citizen Scientists in the field
Citizen Scientists in the field

Recent studies from University of California Los Angeles have predicted, under the most conservative estimates, there will be a 48% increase in days of extreme heat (95+°F) within Riverside by midcentury and a 166% increase in Los Angeles. For Los Angeles this means not just 6 days of unbearably hot weather, but 16 days of needing to stay cool! Extreme heat is not the only factor to consider when looking at how urban trees prosper or even survive. Humidity or lack thereof (aka atmospheric drought), can be just as important especially here in irrigated urban southern California extreme low humidity.

A spectrum of responses to drought stress in plant includes on one end “drought tolerant” plants to the other end being “drought avoidant” plants.  Drought avoiding plants close their stomata (microscopic openings in the leaf surface that let out water and let in CO2) in response to drought stress, evading the effects of extreme water loss through the leaf but this also halts photosynthesis. Given that photosynthesis is how plants “feed” themselves by converting sunlight and water into carbohydrates, this strategy may prevent water loss but it is a short term strategy in that the plant can only “starve” itself for so long before it dies. On the other hand, drought tolerant plants keep their stomata open regardless of drought conditions, allowing for constant photosynthesis. To compensate for water loss, they have better adaptations at finding water, for example by having deeper tap roots or through their leaf, stem, and wood architecture. However, keeping stomata open in extreme aridity puts a plant at risk for embolisms (air pockets) to open in their xylem (water-transporting vessels). Too many embolisms result in branch death and potential total mortality.

The maximum summer temperature gradient across the greater Los Angeles region. The diamonds represents some of the trees sampled by citizen scientists for the project to date.
The maximum summer temperature gradient across the greater Los Angeles region. The diamonds represents some of the trees sampled by citizen scientists for the project to date.

Interestingly, there appears a large amount of variation across different kinds of plants in their drought coping mechanisms, some plant species tending to use more drought avoidance strategies (by closing their stomata), whereas others  use more drought tolerant strategies. Each one has its strengths and weaknesses. I am interested in understanding which of these strategies is adopted by the different tree species in southern California and whether this informs which species will best survive the new (hotter and drier) climate of Southern California.

To study this question, I am taking advantage of the natural gradient of increasing temperature and aridity found in Southern California as one travels from the cooler moister coast into the hot dry desert conditions found further east. See the inserted Figure– here you can see that the temperature gets redder (i.e. hotter) from left to right as one moves from the coast to the desert. The is a similar gradient from west to east in  vapor pressure deficit (VPD); a variable that measures the atmospheric demand for water – which itself is related to air temperature – hotter air being able to absorb more water.  As a general rule, the coast tends to have more optimal VPD for plant growth than the drier (and hotter) more desert-like regions to the east (think Palm Springs). Trees that are struggling to grow and survive in the hotter and drier regions (e.g. Coachella valley) today, will start to struggle in the near future when climate change brings that same extreme weather westward into the central valley.

Citizen scientists are helping me find and measure the trees along this west to east gradient. On each tree, I am collecting detailed information related to how each species is performing, including  measurements of leaf conductance (gas flow from the leaf), leaf and stem water potential (the ability of water to move through a leaf or stem), and stem hydraulic conductance (the efficiency of a stem to transport water).  Through these measurements, we determine at what point a species will close its stomata in response to drought conditions among other things. These measurements will be combined with other data I collect on each tree (leaf thickness, wood density, etc.) to give a more complete understanding of the strategy trees are taking to deal with the local climate. Together, this information will allow us to understand just which strategy each tree is using to survive the “drought”.

The maximum summer aridity (Vapor Pressure Differential, VPD) gradient across the greater Los Angeles region. The diamonds represents some of the trees sampled by citizen scientists for the project to date.
The maximum summer aridity (Vapor Pressure Differential, VPD) gradient across the greater Los Angeles region. The diamonds represents some of the trees sampled by citizen scientists for the project to date.

Finally, by assessing different individual tress across the climatic gradient of temperature and vapor pressure deficit they occur in, we can also understand whether the same species can alter its strategy depending on conditions (i.e. showing a flexible strategy), or whether the species is inflexible and cannot alter its strategy in dealing with drought conditions and there may be more vulnerable to changing conditions. Ultimately I want this information to get into the hands of those who plant trees (e.g. TreePeople, Amigos de los Rios) as well as interested communities so that the right tree is planted.

To date, I have collected data on the first sample of 10 species collected by citizen scientists (Operation Resilient trees 1.0) and am starting the analysis. I am starting to analyze the data from this first round and will go back into the field to sample the next sets of trees in a few months. Stay tuned to see what I find!

Educator Corner: Citizen Science in the Classroom

Citizen science is a great teaching tool. In the Educator Corner, we hear from teachers who have partnered with Earthwatch’s Urban Resiliency Program in Los Angeles to enhance learning opportunities for their students. They share tips and inspiration about involving students in tangible contributions to science.  Contact us to learn more about becoming a partner with Earthwatch.

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Cal State LA Biology Students

Citizen Science in the Classroom: An Interview with an Educator

MauraPalacios
Palacios Mejia, Cal State LA

Maura Palacios Mejia is a Lecturer at California State University, Los Angeles and a PhD Candidate at Texas A&M University.  Palacios Mejia partnered with Earthwatch in 2015 in order to integrate citizen science into the classroom for her course “Writing for Biologists 320”.  We asked her about her experience and about why she recommends her colleagues and other teachers to get involved with Earthwatch as educators.

How did you integrate the Resilient Trees project into your syllabus?

The Resilient Trees Project was incorporated into the syllabus of the Writing for Biologists 320 course at California State University, Los Angeles in three forms. The first was the introduction of the material via the PowerPoint provided by Earthwatch with slight modifications to accommodate our class. I added iclicker questions and gave students information regarding logistics and field safety. I brought the field equipment and samples of the leaves, flowers, fruit or seeds to the classroom so the students would become familiar with identifying tree species and using the sampling methods. Next, we went into the field to do sampling in groups of five students.  Students did fieldwork in two different parks in Los Angeles – Debs Park and Hermon Park – to maximize results. Lastly, each student wrote up a research paper on topics related to the data they collected in a bigger context.  Students connected what they learned in the field with topics related to urban forests like pollution, climate change, drought, and health benefits.

What made this project appealing in terms of integrating it into your classroom plan?

Three major aspects of this project were appealing for students in this class. The first was introducing them to the concept of citizen science, where anyone can complete training and contribute to science. Another aspect was how the project was in local environment where students live their everyday lives. The field sampling is a great opportunity for students to connect to the natural environment via sampling and relate what they observe locally to major ongoing issues in science. The contribution of students to a real ongoing project was also great incentive for student participation and achieving a high success rate in the field data collection. Many students collected data beyond the minimum requirement because they enjoyed the experience.

Would you recommend other teachers/professors adopt this project into their lesson plans, and if so, any words of encouragement you would want to share with them? 

I would definitely recommend other teachers and professors to participate in this wonderful project because the students get a sense of accomplishment and an experience they can share with others over their lifetime. By acting as citizen scientists, students are naturally incorporated and exposed to real world science in their community. For me, taking the classroom outdoors and seeing the reaction of students to their own discoveries is always the most rewarding part of my work as an educator. In addition, the writing exercise is a fascinating way to demonstrate the critical and analytical thinking of the student’s perspective in different scientific possibilities driving the biology and diversity of trees.

 

 

Lab Corner: The Ecology of Cities

The Ecology of Cities

by Steven Crum, PhD CandidateCrum_photo, UC-Riverside
Dr. Darrel Jenerette’s Landscape and Urban Ecology Lab

At the Jenerette Lab, we are recruiting citizen scientists from coastal, inland, and desert southern California to help us gather data on park and street-side trees. Citizen scientists will collect leaf samples from cities around southern California to see how different urban environments affect trees. Climate change will impact urban tree species differently, as some trees do not prefer high heat environments. This project will help us understand which tree species will thrive in warmer environments, and which will provide the most cooling benefits. The sheer volume of samples that are need for this project would not be possible without the help of citizen scientists. Since we have received so much support for our efforts, I thought I would take the time to describe two areas of research in our lab that I find particularly interesting.

Cooling Benefits of Trees

wireless temperature sensors
Wireless temperature sensors we installed on trees

Starting in the mid-20th century, large cities in the Unites States began heating twice as fast as surrounding rural and natural areas, especially in the southwest, mostly due to the urban heat island (UHI) effect. The UHI is created by increasing built surfaces and decreasing vegetation, creating higher temperatures in city centers compared to surrounding rural and natural areas. Rising urban temperatures are predicted to cause shifts in wildlife distributions, increases in pathogen and disease spread, increases in global greenhouse gas emissions, increases in energy consumption associated with air conditioning, negative impacts on human health from heat related illnesses, and deterioration of air and water quality. The UHI can be mitigated through vegetation, especially trees.

Over the past two years our lab installed around 500 small wireless temperature sensors, right, in street-side trees. Counterintuitively, we found that trees reduce urban air temperatures most at night. During the day trees shade built surfaces, including side-walks and streets. Since shaded surfaces absorb less heat in the day, they warm the air less at night. Additionally, this effect is not equally distributed across city neighborhoods in part because low-income areas have fewer trees.

thermal infrared image
Surface temperature measured with thermal infrared image

This summer we will pair air temperature with surface temperature measurements in urban environments to see how built surfaces and trees affect the UHI. We will measure surface temperature with thermal infrared imagery, pictured right, which, I am almost certain, is the same technology used by the invisible creature in the movie Predator!

 

Urban Greenhouse Gas Emissions

Our lab is also investigating a phenomenon that has global-scale consequences, CO2 emissions. Greenhouse gas emissions, including CO2, are produced by a wide variety of sources. Human-caused emissions range from fossil fuel combustion to land-use change. Like its name implies, land-use change is the conversion of natural ecosystems into cities or agriculture—changing plant and soil composition. Because plants absorb CO2 and soils release CO2, land-use change hinders the environment’s ability to manage climate change. We have found that urban land-use conversion in southern California accounts for increases in soil CO2 emissions by 200% to 15,000%! Additionally, increasing temperatures with climate change will likely increase urban soil CO2 emissions more than that of natural ecosystems. On the other hand, drought will likely have larger emissions impacts on natural ecosystems, since they are dependent on rain and not irrigation inputs.

Cities are hot spots of environmental change. They alter land-use, biodiversity, green house gas emissions, and water and nutrient cycles. For urban residents global environmental change is magnified by changes in the local environment. We hope our efforts, and those of citizen scientists, will help society anticipate and mitigate for the changing ecology of cities.