Science Power Guide (2024) PDF

2 0 2 4 30 YEARS SO DO 2 0 2 5 YO IN U GO CA U EDITION...

2 0 2 4 30 YEARS SO DO 2 0 2 5 YO IN U GO CA U EDITION N RB DO E POWER GUIDE YO ST UR S SCIENCE SCIENCE Our Changing Climate ALPACA-IN-CHIEF Daniel Berdichevsky r This guide breaks down an introduction to environmental science into bite-sized, easily digestible statements. Here are a few style notes for those new to DemiDec: ▪ Bolded terms flag key terms and phrases. They are grouped and defined in the power lists at the end of the guide for quick review. ▪ Additional information is flagged in a plain footnote that clarifies areas of vagueness or inaccuracy in the guide, or as an Enrichment Fact for the curious. Additional commentary, sarcasm, and humor can be found in signed footnotes. Curriculum breakdown 1 4 20% 20% 1 2 3 4 3 2 30% 30% Here are some study tips if you’re having trouble deciding how to start: ▪ If you have one month left, review the resource guides ▪ If you have one week left, look over your Power Guides (like this one!) ▪ If you have one day left, check out the Cram Kits, take a deep breath, and get some rest.  ▪ ▪ ▪ INTRODUCTION  Environment and Organisms  An organism lives in a specific place surrounded by other organisms  All the living and nonliving parts of an organism’s world are its environment  Living parts of an environment include plants, animals, and bacteria  These living elements are the environment’s biotic factors  Nonliving parts of an environment include sand, water, and rocks  These nonliving elements are the environment’s abiotic factors  These aspects work together to affect1 environments at different scales  An organism’s immediate surroundings are its local environment  The global environment is all aspects of the Earth Biotic Factors Abiotic Factors Habitat (trees, plants, bushes) Habitat (rocks, sand, and water2) Food (prey, plants, fruits) Weather (precipitation, pollen, pH) Alive things (plants, animals, bacteria) Quite literally anything nonliving ENVIRONMENTAL SYSTEMS  One Environment, Many Systems  An environment is all the biotic and abiotic factors of an organism’s world  These living and nonliving factors are closely interconnected  A change in one factor will affect many other factors  Examining an environment is a daunting task  We can divide an environment into examinable sections  We can look at just a subset of connected biotic and abiotic factors  A subset of connected biotic and abiotic factors is a system  A change in one system will affect other systems3 1 2 3  All the systems of an environment work together  This interaction of systems and subsystems is called system dynamics  Systems Depend on Exchange  Systems either exchange matter or energy Bee lands on a flower  Matter exchange is like bees pollinating flowers to get nectar  This relationship is a mutually beneficial matter exchange4 Bee picks up some  The bees get nectar pollen  The plants can reproduce  Both sides benefit from the interaction  Some matter exchanges are not mutually beneficial5 Bee goes to new  An example of a one-sided exchange is plants and flower for nectar soil The plants get nutrients from the soil  Some pollen falls off  The soil does not get anything into new flower  Water is the most crucial matter exchange  Energy exchange is like burning coal  Energy transforms from coal into heat Pollen fertilizes the  The heat boils water new flower  The water turns into steam  The steam turns a turbine and powers a generator6 New flower produces  The generator creates electricity seeds or fruit  The Sun’s energy powers all environmental systems  Open or Closed?  A system that allows exchange is an open system  Exchanges can be only matter, only energy, or both  An example of an open system is the Earth and energy  The Earth system is open to energy from the Sun system  The energy from the Sun is in the form of solar radiation  The Earth’s environmental systems all rely on the Sun for energy  A system that does NOT allow exchange is a closed system  Both matter and energy exchanges do not occur in a closed system  An example of a closed system is the Earth and matter  The Earth system is considered closed to matter exchange  It is rare for matter to enter or leave due to the Earth system’s atmosphere  The Earth system does have infrequent matter exchange  An example are meteorites  These are meteors that that did not burn in the atmosphere  Another example is space exploration vehicles  These matter exchanges are rare enough for the system to be deemed closed  A system can be selectively open or closed  A system can be open for only energy 4 5 6   The Earth system is a great example  A system could also be open for only matter  Think of a container with some pizza inside  There is no energy exchange, but the pizza can be moved  Lastly, a system could be open for both matter and energy  You are a fully open system  You exchange matter by eating food  You exchange energy by walking Open System Closed System Earth System Energy ✓ X X Matter ✓ X ✓  Systems Are Subjective  A system depends on the observer and scale  The Earth is a complex global environment  The largest system of this environment is the Earth system  The four main subsystems of the Earth system are the “-spheres”  This includes the atmosphere, biosphere, geosphere, and hydrosphere  Earth-system scientists study these systems as well7  We can zoom into a system to discover many more systems  Imagine that you and I are wildlife biologists  We want to observe a red panda’s lifestyle  Red pandas live in bamboo forests in Asia  The bamboo forest is a red panda’s environment  A bamboo forest can be divided into many systems  Broadly, a forest falls into ALL the -sphere subsystems  These systems are all closely connected and often overlap  As wildlife biologists, we would be concerned with the biosphere system\ Forest Red Panda Ecology Behavioral Ecology What are the daily How does the red interactions in the panda interact ecosystem? with other species? What is the How do nutrients diet of the flow through the red panda mainly forest? composed of? These questions are general and These questions address various are very specific to subsystems the red panda 7   However, we are specifically interested in red pandas  The biosphere system has many subsystems8  We would need to zoom into the biosphere system  A general subsystem would be the forest ecosystem9  On a smaller scale, we can better observe a red panda and how it lives  Zooming in closer can help us better achieve our goal  We can look at the behavioral ecosystem of a red panda  This system observes how the red panda behaves within its ecosystem  An ecosystem is all the biotic and abiotic factors of an environment  If we want to observe the forest in which a red panda lives, we would be concerned with the biosphere and geosphere systems  Our scale would be much larger  We might look at just the forest ecosystem  We could also look at the soil system or nutrient cycle system  If we were interested in saving the red panda from, we would observe the impact of human activities on red pandas  This field is conservation biology  Conservation biologists often deal with many human aspects  They must engage with politics, policy, and economics10  A conservation biologist might help to pass legislation System Purpose Relationship Earth System Largest system on Earth The entire Earth Biosphere All life on Earth Earth subsystem Forest Ecosystem Forest’s biotic + abiotic parts Overlaps all 4 subsystems Behavioral Ecosystem Behavior in an environment Forest subsystem Nutrient Cycle System Track nutrient flow Forest subsystem Soil System Study plant growth Nutrient cycle subsystem  That’s a Lot of Overlap  The scientist’s goal determines what the system(s) they will observe  Because systems overlap, we can analyze multiple systems at the same time  As wildlife biologists, we observed a red panda’s behavioral ecological system  We can also look at its microbial system  Additionally, we could observe their population dynamics  How do their populations operate?  What are the interactions in the population?  We call this field population biology 8 9 10   Human Overlap  Humans will inevitably affect environmental systems  Laws and policies affect environments Forms of  California’s electric vehicle mandate11 will impact many Human Impacts environmental systems and subsystems  The strength of an economy affects a country’s dedication Resource to improving the environment Usage  A country in a recession is focused on saving itself  Their current priorities are not environmental systems  People will always want to save themselves first Government ENVIRONMENTAL SCIENCE Economics  Humans Impact the Environment  The parts of an environment are called systems  Remember, systems are subjective  Environmental scientists use two scales to view human impact  The small-scale views impact at the individual level  An example is the environmental effects of burning a candle  The large-scale views impact at a massive level Small-scale Large-scale Turning a fan on Draining a lake Recycling a plastic bag Changing the climate Driving to a 7AM scrimmage Clearing land for a parking lot  Scientists want to understand the world methodically and rationally  To do so, they try to be as objective as possible  An objective method of understanding is the scientific method  Scientists can use the scientific method to conduct experiments  These experiments are used to understand the world around us  The scientific method is widely accepted in the science community THE SCIENTIFIC METHOD  Do You Even OH-PEC-CD, bro?  The scientific method has seven steps 11   Each step flows into the other Observe Hypothesize Predict Experiment The Scientific Duplicate Communicate Conclude Method  Observe  The initial step is to notice something happening  Why is the observed situation occurring?  One day you observe a moldy orange on your counter  An orange in your fridge, however, is normal  You know you bought them on the same day…  Why is one moldy while the other is unchanged?  Hypothesize  To come up with a hypothesis, you try to explain what you saw happening  What factors caused it?  The cause is expressed with a statement explaining what might have happened  A hypothesis is a clear, testable, general statement explaining the “why”  A hypothesis is a plausible explanation for what was observed  The goal is to explain what caused the occurrence  A hypothesis will either be rejected or not rejected12  Typically, a null and alternative hypotheses are used13  The moldy orange was left out in the summer heat  The normal orange was in the cool fridge  Maybe the different temperatures affected the oranges  Hypothesis: Temperature affects mold growth rates of an orange Null Hypothesis Alternative Hypothesis Nothing special will happen Something special will happen “Temperatures don’t affect mold” “Temperatures affect mold”  Predict  To predict, you must take a stand on your hypothesis  From your observations, do you think the hypothesis will be true?  You will test this stance with an experiment 12 13   Prediction: Higher temperatures will increase orange mold growth rates  Experiment  Get conclusive data to reject or fail to reject the hypothesis  A larger sample size generates more data14  Using 1,000 people instead of just 10 is also more representative  A researcher can collect data non-intrusively  This approach is called an observational study  The scientist makes observations about the natural world  No factors are altered in this form of experimenting  A researcher can also manipulate a factor to see its effects  We call this a designed experiment  A designed experiment has a factor that is changed  This changed factor is the independent variable  The independent variable is hypothesized to be the cause  An independent variable is changed to see how it affects another variable  This other variable is called a dependent variable Independent Variable Dependent Variable The variable being changed The variable experiencing the changes Ex: Temperature in our experiment Ex: Mold growth in our experiment  Often, a designed experiment is single-blind15  A single-blind experiment divides participants into two groups  The group that receives no change is the control group  The group that receives the change is the experimental group  The purpose of a single-blind experiment is to minimize bias16  Only the researcher knows who is in each group  The control group is given a placebo17  The placebo helps maintain a sense of consistency  The orange-mold test would be a designed experiment  Fifty oranges are in our experimental group  Twenty-five will be kept in the fridge  Twenty-five will be left outside  We can use freshly bought oranges as a control group 14 15 16 17   The independent variable is the temperature  The dependent variable is the mold growth rates Observational Designed Study Experiment Observe what Change something normally happens to see the effects Nonintrusively Intrusively collect data collect data EX: Does EX: How does a temperature affect drought affect orange mold zebra populations? growth rates?  Conclude  What has the experiment revealed?  In the orange experiment, we conducted the testing for a month  We found overall barely any mold on the twenty-five fridge oranges  The 50 oranges left outside had significant mold growth  Comparing these to oranges at the store, the temperature affects mold growth  Are you going to reject the null hypothesis? Fail to reject it?  We have overwhelming data to support our orange hypothesis  We can safely fail to reject that temperature affects mold growth rates of an orange  The hypothesis can also be modified and retested  We might retest if the data is inconsistent or inconclusive  Communicate  The information can now be turned into a coherent document or research project  The data and writeup can be published in a journal or other scholarly database  Publishing allows others to peer-review18 your findings  Duplicate  Similar results across multiple reiterations of an experiment solidify the results  Different scientists can replicate the experiment and validate conclusions  The research project often describes the experiment setup process  A scientific finding is data from a hypothesis that many experimenters agree about  Hypotheses can lead to theories when they are supported by lots of evidence19  Theories can help scientists discover laws by showing consistent patterns 18 19   The First Law of Thermodynamics is one such law  This law states that energy cannot be created or destroyed  Instead, energy only changes form A testable explanation for an observation; Hypothesis either rejected or failed to be rejected Example: Oranges mold faster in heat A well-tested idea that explains why something Theory happens Example: Theory of Evolution A universal rule that will always work the same Law way in nature; either disproven or not Example: Newton's Laws of Motion  One experiment and one conclusion do not mean much on their own  Sometimes, experiments tun up conflicting results  Conflicting results do not invalidate the scientific process  Initial findings on hot topics like climate change can be hurriedly published  These initial results could be contradictory  The media might interpret contradictory results negatively20  The public’s consensus on the topic is then conflicted  Reading through experiments can help explain discrepancies  It is important to view all findings critically  How do we know it can be trusted?  What caused these outcomes?  Asking questions helps determine if researchers conducted a “good” study  Was the sample size large enough?  A large sample size lowers the chance of outliers21  Were the control and experimental groups distinctly different?  A proper experiment will try to maintain a distinction  This requires more effort but ensures more accurate results  Did the independent variable cause the dependent variable to change?  Correlation does not always imply causation22 ENVIRONMENTAL INDICATORS  Indicators Indicate  We cannot measure ALL parts of a system 20 21 22  A system is made up of interconnected parts  These can be living, nonliving, or both  The main idea is that changes in one part CAN affect the others  We pick reliable indicators to gauge system health  Indicators are measurable signals that can hint towards quality  For example, a doctor uses an X-ray to check for fractures  Sadly, there is no global indicator of environmental health  We use six MAIN indicators Indicator Global Human Biological Food Resource Temperatures Pollution Population Diversity Production Consumption + Greenhouse Levels Growth Gas Levels  Never Judge a Book by Its Cover  Context is key when we evaluate indicators  You should never evaluate an indicator without looking at the context  Many factors can affect an indicator  A great idea is to ask questions  When was this indicator measurement taken?  What was used to measure the indicator?  Why is this the measurement?  Are there any external factors affecting the reading?  Conducting multiple trials helps to see if an indicator is indicating  You would not measure a plant’s height only once if you were trying to assess its growth  Consistent readings show that an indicator is doing its job  Verifying these readings is also extremely important  Experiments can provide verification TYPES OF BIODIVERSITY  All the Biological Diversity of the Earth  Biological diversity includes four types of diversity Biodiversity Types  We only care about the species diversity indicator  The global species diversity indicator is used to Species Ecosystem determine environmental quality Genetic Habitat  Environmental quality measures the health of the environment  The global species diversity indicator shows that quality has declined  Species Diversity  Scientists group all living things into categories called species  We learn ALL about this in Section II  You are probably familiar with the concept of species   For example, dogs are one species and humans are another  It is not always easy to tell where one species ends, and another begins  Dogs and wolves are sometimes considered one species  Other times they are thought to be two distinct species  Scientists categorize species based on several factors  They may look at an organism’s biochemistry  This includes their DNA, RNA, internal structures, and pathways  They may categorize species based on their appearance  The physical appearance of a living thing is its morphology  Morphology includes anatomy, shape, size, and color  For example, does it have four legs or two?  Scientists may also look at how an organism functions and lives  The study of an organism’s functions and behaviors is known as physiology  How does it interact with its environment? Other species?  Physiology covers processes like reproduction and homeostasis Factor Definition Example Biochemistry Chemical processes Human DNA vs Dog DNA Morphology Looks Birch leaf vs Maple leaf Physiology Function and behavior Egg birth vs Live birth  So far, we have found and recorded 1.8 million species  Scientists estimate there are currently 10x as many on Earth  We just need to discover them  Species diversity is measured by how many species there are per functional group  A functional group is a group of species that share a similar role  Examples are pollinators, decomposers, and predators  Habitat alteration affects species diversity  An endangered species is at risk of extinction  The Bengal tiger, snow leopard, and West Indian manatee are some examples  Without action, they will die off  Awareness can help to protect endangered species  Similar efforts helped save the bald eagle and American bison Endangered Species Saved Species Bengal Tiger Bald Eagle Snow Leopard American Bison West Indian Manatee -  A keystone species is an ecosystem staple  Ecosystems rely heavily on keystone species  Keystone extinctions can destroy an ecosystem  If there were no spiders, bug populations would explode out of control  ~99.9% of species that have EVER lived on Earth are extinct  They died off naturally in a process called background extinction (BE)   BE arises from competition, predation, disease, environmental shifts, and natural events Background Extinction Competition Predation Disease Environmental Shifts We estimate the background extinction of pre-human times by looking at “quiet” periods  Quiet periods are times with no big, extinction-causing events  Post-human BE is easier to calculate than pre-human BE  Humans are killing species faster than BE ever did By the Numbers  We are causing mass extinction rates Humans cause extinctions up  A mass extinction rate occurs when many species to 100 times faster than BE die in a short period of time ~ 40,000 annual species  Humans cause habitat loss and degradation extinctions from humans  Habitat loss examples include deforestation negatively affecting habitats  A forest is cut down to expand a town Current BE every century is  The homes of many species are lost two mammal extinctions  Animals cannot find a suitable home per 10,000 species  The species cannot reproduce and dies out  Habitat degradation examples include pollution  A farm’s pesticide runoff flows into a river  River-dwelling species ingest the pesticide  As a result, they die from pesticide poisoning WORLD HUMAN POPULATION  “There’s 8 BILLION of us.” –United Nations, Nov. 2022  We have a daily net growth of 230,000 people  148,000 people die each day  378,000 people are born each day 378,000 148,000 230,000 births deaths net  Human population growth has slowed  Our population experienced exponential growth until the 1960s  The rate every year, until the 1960s, was greater than the previous  Exponential growth is growth at an increasing and non-linear rate  An example is the graph of y = 3x  Currently, the human population is still growing  The United Nations predicts it will stop in 2150  The population then will be around 8-12 billion people   It’s a Mixed Indicator  The global population is still growing  The United Nations projects that population growth will end in 2150  People tax the Earth’s finite resources  More people will use more resources to survive  Increased populations also increase pollution and waste  We have yet to find a sustainable way to deal with these issues More Resources More Waste More People Used Generated RESOURCE CONSUMPTION  Consumption Affects Ecosystems  Using resources wisely so some remain for the future is sustainable use  Unsustainable usage can affect impact ecosystems on various scales  Rapid resource usage indicates unsustainability  Resource consumption is a good indicator of environmental quality  Resource usage boosts human life quality  At the same time, it negatively affects environmental quality  Thus, resource consumption is a useful indicator  More People, More Problems  A larger population will naturally consume more resources  An increase in resource consumption impacts the environment  Excessive consumption can negatively affect environments  Location affects resource usage  Per-person usage changes between scales, regions, and economies  For example, people living in large houses in the suburbs will, per person, consume more resources than a people living in an apartment  It takes much more energy to light and heat a large house than a small apartment  People living in dense cities tend to drive less than people living in suburbs  They both impact the environment, but to different degrees  Lifestyle also affects resource usage The 20% of the population in developed countries: Uses 58% of the Eats 45% of the Consumes 84% of Owns 87% of the world’s world’s meat and fish the world’s paper world’s automobiles total energy Meanwhile, the lowest global 20% has a stake of 5% or less in each  A lavish king and a poor peasant both use resources  The king will use more resources, and impact the environment more23 23 FOOD PRODUCTION  Breaking: Humans Eat Grains  Grains compose more than 50% of the calories eaten by humans  Many foods are made from grains  You have most likely had multiple forms of grains today  You may have had cereal for breakfast, a sandwich for lunch, and some Cheez-Its for a snack  Since grain is always in demand, we grow a great deal of it  Intensity is the number of crops grown per hectare  A hectare is a unit of measurement for an area  One hectare is roughly equal to 10,000 square meters  Some farmers specialize and grow only one crop  The practice of growing only one crop is monoculture24  Monoculture fields are densely planted  Monoculture is a high-intensity practice  These farmers grow many crops per hectare to maximize yield  Yield is measured in crop tons per hectare  A higher yield generally means a more intensive practice  High-intensity agriculture usually causes a lower soil quality as the soil’s minerals are used up  Over time, high-intensity practices can cause yield rates to fall  High-intensity practices harm the environment  Soil erosion and fertilizer runoff degrade environmental quality  Degradation can harm ecosystems and upset careful balances  In the short-run, monoculture is economically efficient  It is easier to plan, manage, and harvest a single crop  Farmers can also diversify and grow many different types of crops  Growing many crops is called polyculture and is typically low-intensity  Although polyculture is less economically efficient, it is more sustainable High Intensity Monoculture Degraded soil quality Decreased yield over time More taxing on environment Low Intensity Polyculture Better soil quality More crops grown over time Less taxing on environment  Many variables go into global grain production (GGP)  Climate, water availability, and soil quality all affect GGP  These factors make GGP an excellent environmental indicator 24   If GGP falls, we know that the environment has degraded GLOBAL TEMPERATURES AND GREENHOUSE GASES  Factors of Earth’s Temperature  Both internal and external factors affect Earth’s temperature  Solar radiation comes from outside the Earth and is an external factor  Atmospheric gas levels come from inside the Earth system and are an internal factor Solar Gas Radiation Levels Earth's Temperature  Greenhouse Gases: Dutch Oven-ing the Earth  Greenhouse gases are named for their ability to let sunlight in and trap it  They act like the glass of a greenhouse  The glass allows in sunlight and heats up the inside of the “house”  The heat cannot escape through the glass  Trapping heat in a closed environment creates a humid microclimate  A microclimate is a localized climate different from its surroundings  Gardeners use greenhouses to grow plants in areas or during seasons in which they would not otherwise survive  On a larger scale, Earth’s atmosphere causes a similar effect  Gases in the atmosphere trap heat near the Earth’s surface  Without these gases, life would not have evolved on Earth  However, an increase in greenhouse gases causes too much heating  Two important greenhouse gases are carbon dioxide and methane  CO2 and CH4 have always existed naturally in the atmosphere  However, burning fossil fuels releases both gases into the atmosphere  Human activity has caused atmospheric levels of these gases to rise  We use the word anthropogenic to refer to humans-caused changes  CO2 and CH4 occur in the atmosphere both naturally and anthropogenically  These two gases play a dominant role in global temperatures  Temperatures have trended upward for 130 years  Similarly, concentrations of CO2 and CH4 in the atmosphere have increased too  Human activity is widely agreed to be the cause of the global temperature changes  We caused this global heating by burning fossil fuels and deforestation Methane Carbon Dioxide Nitrous Oxide Greenhouse Gases CASE STUDY: MEASURING GREENHOUSE GASES IN ICE  An Icy Time Machine  Extreme places like Greenland25 and Antarctica have ice sheets and glaciers  These ice sheets and glaciers are made up of layers, like onions26  These layers build up from new snow falling onto old snow  The accumulation traps current gases and preserves them via freezing  Imagine a really cold time capsule of gases  Scientists extract samples called ice cores from these ice sheets and glaciers  The samples’ slices are each assigned a year  A slice is an individual layer of an ice core  These slices resemble ring in a tree stump  The year a slice is assigned depends on when it was the newest layer  For example, a slice given the year 1970 was the freshest layer in 1970  The slices are analyzed for their gaseous concentrations  The concentrations show what the atmosphere was like at that time  More recent layers contain anthropogenic pollutants  Analyses show varying temperatures and concentrations  The past 160,000 years have not been a steady rise/fall  Carbon dioxide and methane have been fluctuating  Appropriately, global temperatures have also been fluctuating  We can also compare oxygen atoms to approximate relative temperatures  The different isotopes of oxygen have different masses  The ratios between these isotopes show warmer/cooler times27  We can compare these ratios to current ratios  The ratios can tell us if it was warmer/cooler then compared to now AIR AND WATER POLLUTION  Lead: The Good, the Bad, the Ugly  Lead is a relatively soft metal  It can be easily shaped with a hammer  Metals that can be shaped this easily are malleable  Lead has been mined for as long as 5,000 years  The Industrial Revolution caused a large spike in atmospheric lead content  Pre-Revolution levels were not nearly this high  Innovations in mining and processing boosted airborne lead levels  One major usage of lead was in gasoline  From the 1920s to the 1970s, lead was added to gasoline to improve engine efficiency  As vehicles became popular, lead demand and emissions increased  Vehicles were the main reason for high lead emissions in the 20th century  After 1975, new United States laws banned cars that used leaded gasoline 25 26 27   This is where we get the term unleaded gasoline28 from  Unleaded gasoline lowered lead emissions  Note that unleaded gasoline still contains some lead29  Lead Is Toxic  Lead breaks down the human nervous system  It interferes with neurotransmitters and neuronal function  It also causes a whole host of other problems  Extreme exposure can kill in a matter of days  Lead is more lethal to fetuses and children  It also kills plants and can severely disrupt ecosystems  Pre-1960s houses were painted with lead paint  These paints could contain up to 50% lead  Obviously, this is bad for humans  Older houses have older paint that can crack and peel off  When this toxic paint cracks, lead dust is created  Lead dust can be easily disturbed and become airborne  Additionally, kids can accidentally eat chipped lead paint  Long-term exposure and accidental consumption are fatal  Thankfully, the EPA banned lead-based paint in 1978  A more prominent source of lead pollution is drinking water  Poorer and older communities are particularly likely to suffer from lead pollution30  The housing is old, and plumbing has not been replaced in such areas  Lead plumbing can leech lead into the water  Higher-acidity water has the potential to corrode lead pipes  This corrosion can lethally contaminate the water  A constant source of lead pollution has been fossil fuels  The burning of fuels like coal, oil, and unleaded gas releases lead  Although the concentrations are small, it has accumulated over decades Lead In… Purpose (Back Then) Problem Paint Used in older homes Lead dust and flakes Gas Helped engines run better Toxic exhaust Pipes Create piping for plumbing Contaminates water  Lead Presence Indicates Environmental Quality  Lead content in the air, water, and land indicates pollution levels  We can also predict the harm to the natural environment with this measurement  Lead emissions are improving  However, large quantities of lead are still mined and processed globally 28 29 30   These actions continue to emit lead into the atmosphere LIMITATIONS OF ENVIRONMENTAL SCIENCE  We Are One-of-One  Earth is a unicorn planet  Earth is the only life-sustaining rock we know of in the expanse of space  We would not be here without the Earth  Earth has been permanently changed by humans  We use resources, change the landscape, and pollute the environment  Human activity has transformed almost every corner of the Earth The smelters Roman Empire Smelters were Lead remains in emitted used to obtain the Greenland needed metals quantities of different metals ice sheet lead PCBs were PCBs ended up Penguins have They are not widely used in biodegradable in water and PCBs in their manufacturing atmosphere fatty tissues Americans The common Common carp Americans carp is now in wanted more was a popular brought the fish the United food to hunt game fish from Europe States  There is no other planet like Earth  So, there is no “control group” to see how much our world has changed  We will never know the original levels of things before anthropogenic change  We Stay Inconsistent  Energy occurs in many forms  Energy can take the form of light, heat, or electricity  Scientists tend to use either calories or joules to describe quantities of energy  The rest of the world uses a plethora of different terms Source Measurement Gasoline (United States) Gallons Gasoline (Globally) Liters Electricity Kilowatt-hours Heat (Globally) Celsius Heat (United States) Fahrenheit Peat British thermal units Crude Oil Barrels   Pick A Poison  Determining what's definitively better for the environment is often unclear  There will always be a tradeoff31  A tradeoff means sacrifices  Every choice has its own impact on humans and the environment  The impact is dependent on individual decisions  You can pay for a reusable cloth bag OR use the free plastic bags at checkout  The cloth bag costs money and helps reduce plastic waste  It is made from cotton grown with pesticides that pollute streams  The streams flow into a lake which kills fish that a town relied on for food  The people’s quality of life decreased substantially  The plastic bag is free and is more convenient  It is made from plastic that will take years to decompose  The bag ends up in the ocean, where many species ingest it and die  The environment’s quality greatly decreased  Choices that are better for the environment often lead to a lower quality of life  For example, biking is better for the environment than driving  However, biking home after grocery shopping is very difficult  A balance is difficult to find in this situation  A “good” choice can have many negative implications  Suppose you are buying your first car  You are trying to decide if you want a gasoline or electric vehicle  Electric vehicles are significantly better efficiency-wise  However, the production and fueling processes are not ideal  The batteries use lithium, which needs to be mined  The mining process leads to emissions and pollution  EVs use electricity mostly generated by fossil fuels  The fossil fuels lead to more emissions and pollution 1975 2021 13 miles per gallon 30 miles per gallon  Better Environmental Quality  Environmental quality directly affects human quality of life  Poor air quality is caused by pollutants in the air  This can lead to breathing problems in humans  We can help ourselves and the environment by improving air quality  Scientific advancements can improve environmental quality  Cooperation and action from humans are needed for this  It is difficult to make people change their habits  So, these advancements might take a while to catch on 31   An example is the fuel efficiency of cars in the United States  Fuel efficiency was 13 miles per gallon (mpg) in 1975  This number reached 30+ mpg in 2021  The innovations in fuel efficiency boosted the miles driven per gallon of gas  However, a surprising trend emerged  You would expect people to flock to the more efficient cars  Instead, consumers in the 1990s preferred other vehicles  They favored SUVs, light trucks, and minivans  These tended to be fuel-inefficient and got less than 20 mpg  Human preferences explain this unusual finding  People in the 1990s were shifting to a suburban lifestyle  They had to commute longer distances to work  Families wanted space in their vehicles for their children and groceries  SUVs and minivans seemed more suited for these situations32  A better environment starts with human cooperation  Human cooperation includes many factors  Personal preferences, accessibility, and actions play major roles in decisions  A guy that hates Tesla will refuse to switch to the EV scene  A broke college freshman is not likely to buy expensive solar panels  A billionaire singer needs to use her jet for a thirteen-minute flight33 34 SYSTEM ANALYSIS  Inputs and Outputs  Imagine a Camelid Bank, in which money is constantly flowing in and out  System analysts, like ourselves, call money entering the bank the influx  The words influx and input are synonymous  The money going out of the bank is the outflux  The words outflux and output are synonymous Influx  The bank starts Monday with a total of $15 in cash  This initial value is called a pool  A customer deposits $15 and another withdraws $10  A change in the amount of cash has occurred Bank  This change is called flux  We can find net change by subtracting outputs from inputs  The input was $15 and the output was $10  The total flux was $5  The bank gained $5 in cash Outflux 32 33 34  total influx outflux flux  When the bank opens on Tuesday, the poll will be $20  Suppose one customer withdraws $15 and another deposits $10  The input is $10, and the output is $15  The total flux is –$5  The bank has lost $5 in cash  The total flux value is negative  Suppose one customer deposits $10 and another withdraws $10  The total flux is zero  A total flux of zero means no change  If a system experiences no change, it is in steady state  A steady state system is in equilibrium with no net change total steady 0 flux state  Suppose we find that the Camelid Bank gets $5 in cash deposits every month  A quantified change over a certain amount of time is a flux rate  The Camelid Bank’s flux rate is $5 every month System Analysis Slang Translation Pool Starting value Influx Input Outflux Output Flux Change Total Flux Net change Flux Rate Change over time  Environmental Application  We can apply systems analysis to environmental science  You will recall that an environment comprises interconnected systems  The water in an ocean is in steady state  Water flows in from various sources and also evaporates into the atmosphere  We can only estimate the flux for something as large as an ocean  Systems analysis helps us observe what is happening within a system  A system must take up space for us to be able to observe it  Anything that occupies space has mass  We can also call a systems analysis a mass balance analysis  The formula to analyze the change remains the same  Inputs – Outputs = Net Flux  Systems can be in different states   A part of a system can be in steady state while another part of a system can be unbalanced  The water in an ocean is in steady state  However, the trash in the same ocean is experiencing positive flux  The marine life in the same ocean is experiencing negative flux  A large system will have many fluxes  The fluxes vary based on the components of a system CASE STUDY: MONO LAKE ANALYSIS Between 1-3 million years old Borders Sierra One of the Nevada oldest lakes in Mountain North America Range 300 miles northeast of Mono Borders the Great Basin Los Angeles Lake Desert  Mono Lake’s Four Systems  The natural water system discusses how Mono Lake is a terminal lake  The salt-balance system is about Mono Lake’s steady, growing salt levels  The ecological system talks about the interspecies interactions in the lake  The water-use system details species loss from water diversion  Natural Water System  The water influx comes from the Sierra Nevada mountains  These rivers and streams from the mountains are tributaries  The tributaries bring constant snowmelt to Mono Lake Sierra Nevada Snow melts and The snowmelt Mono Lake mountain has runs down in ends up in water level snow rivers/streams Mono Lake rises  The only water outflux is due to evaporation  Mono Lake does not feed into any other bodies of water  As a result, it is called a terminal lake  The water has reached its “final” destination35  The Mono Lake natural water system is usually in steady state  Salt-Balance System  Snowmelt contains elements like sodium and magnesium  Yes, freshwater has traces of sodium 35   This salt accumulates over time in Mono Lake  The salt concentration of Mono Lake has been increasing  Water outflux only comes from evaporation  Salt is not removed during evaporation  As a result, Mono Lake has been increasing in salinity  The Great Salt Lake and the Dead Sea also have high salinity  They are terminal bodies of water  They have no outflow  Elements like salt gather and gradually increase in concentration  This salt balance system was not in steady state  The concentration was slowly increasing  We can use a mass balance analysis to represent a smaller estimate  The net flux is the difference between the influx and outflux  The influx of salt will be approximately 10 milligrams per liter  There is an input of 5 liters per day  Our salt influx is therefore 5 liters/day x 10mg/liter = 50 mg/day  The outflux of salt is zero  There is no salt leaving the system  The net flux is 50 mg/day – 0 mg/day  50 mg of salt is deposited every day  Ecological System  This system focuses on interspecies interactions  It also observes how species interact with their physical environment  Mono Lake has a relatively simple ecosystem  Photosynthetic algae gain energy from the Sun  They gain nutrients like nitrogen from decaying bodies and excretions  Brine shrimp and flies eat the photosynthetic algae  The brine shrimp and flies live in underwater tufa towers  These towers are made of calcium-carbonate  The gulls feast on the brine shrimp and flies  Water-Use System  Los Angeles wanted water in 1941  They chose to divert tributary water away from Mono Lake  The city took 80.4 million gallons of water every day  The net flux became negative  Water was only lost from evaporation  The water level in the lake 40 years later was 40 feet lower36  The low water levels increased salt concentration  The water that once diluted all the salt was decreasing  There was rapidly more salt per gallon of water  Mono Lake experienced species loss  The different species were unable to get used to the salt levels  Some species used to slowly get accustomed to the salinity 36  The speed of increased salt concentration was too fast for all to adjust  The algae’s nitrogen uptake was slowed down by the high salt levels  Photosynthetic algae require nitrogen to photosynthesize  Their nitrogen supply decreased and stunted population growth  There was less food for the brine shrimp and flies left  The low water levels revealed the tufa towers  The gulls started overeating the now-exposed brine shrimp and flies  Their reproduction rates were not able to keep up  The brine shrimp and flies started to die off  The gulls began to starve to death due to less food availability  The lowered water levels caused dust storms  Receding water levels uncovered alkaline dust  The stirred up dust caused harmful storms  These dust storms affected many wildlife populations, including the gulls  Mono Lake and its biodiversity were dying by the 1980s Species Salinity Impact Algae Nitrogen consumption slowed Brine Shrimp Less algae to feast on Flies Fewer brine shrimp available for food Gulls Reduced food supply (both brine shrimp and flies)  Humans Fix What They Caused  Ecologists and environmental scientists caught on to the crisis at Mono Lake  They relayed their findings to lawyers  They began lawsuits and movements to pass new legislation  The initial legal action failed to make change  Environmental advocates attempted to change the water-use policy through advertising and awareness  Eventually, the Supreme Court of California ruled to protect Mono Lake in 1983  Their ruling said the Government of California had to protect the lake  It required the federal government and state agencies to be more proactive  The decision also led to the passing of new environmental laws  The lake level has slowly been recovering  Increased snowmelt in 2023 has helped aid the recovery process  Greater inflow aided the lake MEAN RESIDENCE TIME  What Time Do You Clock Out?  Imagine a bucket with water flowing in and water flowing out  The influx = outflux = 5 liters per minute  The bucket always contains 5 liters of water  This 5-liter pool is in steady state  New water is constantly replacing the “old” water  What if you want to find out how long water is staying before replacement?  You are trying to find the mean residence time (MRT)  We find MRT by dividing the pool value by the influx  In a steady state system, our influx and outflux are the same  So, we can divide the pool value by the outflux as well  In our bucket situation, the pool is 5 liters  The influx = outflux = 5 liters per minute  MRT = pool ÷ influx  MRT = 5 liters ÷ 5 liters/minute = 1 minute pool influx MRT  The mean residence time of our bucket is one minute  On average, the water stays in the bucket for a minute  Then, it joins the outflux and is flushed out  MRT is the estimated average time  There will always be outliers  Water could stay for ten hours  Water could stay for ten seconds  The mean residence time is the average time  MRT is Useful  We can analyze the mean residence time of many systems  The system being analyzed needs to be in steady state  An important MRT we can measure is the mean residence time of a pollutant  All we need to know is the pool and flux of a pollutant in the water  The MRT of an air pollutant can also be calculated  MRT is how long the average pollutant stays active in the atmosphere  As a result, the measurement is also called the mean atmospheric lifetime  These are estimated time frames  Carbon dioxide’s atmospheric lifetime is difficult to estimate  Carbon dioxide is not destroyed in the atmosphere like other gases  It travels through a process called the carbon cycle  Parts of the cycle can take anywhere from a couple of years to many centuries Greenhouse Gas Atmospheric Lifetime (years) Methane 11.8 CO2 100 Chlorofluorocarbons 100 Nitrous oxides 109 Hydrofluorocarbons 222  No Steady State?  We can only find mean residence time of a system in steady state  A system in steady state has a constant pool  The pool experiences influx and outflux but the pool amount remains the same   The influx and outflux replace the contents of a pool with new material  So, we can calculate how long something will stay in a pool  An unbalanced state implies that there is a gain or loss within the system  We cannot find how long something will stay in a system  The material does not come and leave a pool  There is either an increase or decrease of a material in a pool  We can calculate the speed of the gain or loss of material  You’ll recall this is known as the flux rate  Imagine that you are an aspiring lemonade entrepreneur  The 30-liter vat you have is full of lemon water  You need to add the correct sugar amount  The concentration of sugar cannot be too sweet  The concentration cannot be too low  Through testing, you find that 50 grams of sugar per liter is the best  You set up a funnel that adds five grams of sugar every second to the vat  How long would it take to reach the desired concentration?  The net flux is influx subtracted by outflux  The sugar influx is 5g/sec  The sugar outflux is 0g/sec  Your net flux is 5g/sec  You need a sugar concentration of 50 grams per liter  You have 30 liters of lemon water  You have a net flux of 5g/sec  So, you would need 50g/liter x 30 liters = 1500 grams of sugar  5g/sec x 300 seconds = 1500 grams  The funnel would take 300 seconds to deposit 1500 grams of sugar  The unbalanced vat system experiences a constant flux of sugar  We know how much sugar we want  We found the flux rate of the sugar  Using this information, we can calculate the time we need to stop our flux  We will reach the desired concentration of sugar in five minutes FEEDBACK  It Ain’t Always That Easy  A system is not always as simple as sugar influx in lemonade  Many fluxes take place in an environmental system  Systems work to control and mitigate these fluxes  The systems try to maintain a fragile balance  This fragile balance is often called homeostasis  The human body needs to breathe to survive  There is an input of oxygen and an outflux of carbon dioxide  The lungs diffuse oxygen to the heart  The oxygen is attached to blood cells in the heart  This oxygenated blood flows through the body   Oxygen is delivered to many systems, like the brain  These systems use oxygen to aid in various tasks, like energy production  An activity like running requires extra energy to maintain normal functionality  The lungs need to compensate by drawing more oxygen  The lungs take more frequent breaths  All this extra oxygen must attach to blood cells  The heart beats faster  The blood circulates throughout the body faster  It delivers more oxygen to different systems  The energy production increases to accommodate for the energy used  Systems regulate fluxes to achieve homeostasis  Not The Survey Kind  The way a system reacts to changes and fluxes is known as feedback  Feedback will either be positive or negative  Positive feedback is a movement towards an extreme  An Instagram reel gets many views  The algorithm sees the reel is doing well  The reel appears on more people’s feeds  In this positive feedback look, more views lead to more views  Negative feedback is a movement towards homeostasis  These feedbacks are a checks-and-balances loop  It works to move a system towards back to a set point  A set point is the equilibrium point in a given system  When you are running, your muscles require more energy to do more taxing work  Without energy, they will not be able to function normally  Your lungs increase their oxygen intake to circulate more oxygen  The oxygen fuels the muscles  Another example is predator-prey relationships in an environment less food is fewer snakes available around to prey more snakes die more food is off from hunger available snake rabbit population population declines explodes rabbit snake population population food sources declines explodes more prey is decline available eaten more by they can easily snakes reproduce more  We can see that the checks and balances help to mitigate population sizes   The rabbit population is kept in check by the snakes  The snake population is kept in check by the rabbits  This negative feedback loop helps move the population to homeostasis Positive Feedback Negative Feedback System is moved away from System is moved towards homeostasis homeostasis A process is amplified towards Checks and balances to an extreme maintain homeostasis  Bro, I’m Lagging  All systems have a delay  The world you are seeing is a little behind  The lag was caused by the transmittance and processing time in your brain  Your eyes had to send what they through retinal pathways  The information from both eyes was compiled  Then the brain understood what happened  Even though it happened in milliseconds, there was a delay  The same delay applies to environmental systems  A delay in environmental systems can cause long-term damage  Consider the rabbit example: what if the snakes were introduced too late?  The rabbit population starts eating the farmer's plants  Their population grows exponentially in a positive feedback loop  The surrounding food sources are quickly exhausted  At this point, the environment cannot sustain all these rabbits  The delay caused the positive feedback loop to overshoot  The population has increased far more than it should have  The rabbit population has overshot the environment’s carrying capacity rabbit snake population population starts eatting declines farmer's plants rabbit rabbit population population declines increases snakes start eating more rabbits  Starvation causes the rabbit population to decline  The environment’s carrying capacity has been degraded  The population that the environment can support is less than before   We Need Lubrication  A well-oiled engine runs smoothly and more efficiently  Similarly, feedback loops need to be frictionless, so their systems work properly  An environmental system is made of many feedback loops  These feedback loops vary based on different factors  A change in a factor can lead to a feedback loop breakdown  Breakdowns can have a cascading effect on other loops  The system consequences of a breakdown can be measured  Negative feedback loops are measured from a set point  A set point is the equilibrium point in a given system  The deviation from a set point shows what happened to the loop  Positive feedback loops are analyzed for their rates of change  A positive feedback loop amplifies towards an extreme  The rate of change can be measured  A deviation in the rate of change shows the consequences of a breakdown  Let’s get contemporary  A currently relevant set of feedback loops is the Earth’s heating system  We do not know if their net change affects temperatures  The Sun’s energy warms the Earth and increases temperatures  This increased heat causes more evaporation and melting  Less ice means less reflection and increased water vapor  The increased water vapor traps more heat, increasing temperatures  A positive feedback loop results  However, an increase in water vapor also contributes to cloud formation  More cloud clover prevents sunlight from reaching the Earth’s surface  Less heating decreases temperatures  A negative feedback loop occurs POPULATION REGULATION  One species, Many Individuals  A population is a group made up of one species  An example is a pack of wolves  It is useful to specify the scale of a population  An example is the global human population  A population is a system  The inputs to this system are births and immigration  How many species are being born?  How many species are moving in?  The outputs to this system are deaths and emigration  How many species are dying?  How many species are leaving?  Population change is found with the net flux formula  Net Flux = Input – Output  Input into a population includes births and immigration   Output into a population includes deaths and emigration births + deaths + net flux immigration emigration  It is more difficult to estimate immigration and emigration rates  They are harder to observe and record  Analysts tend to favor looking at births and deaths  Populations and their environments work together in a check-balance system  Population size is regulated by systems  Interconnected biotic and abiotic factors make up a system  These factors’ connections create feedbacks  Positive feedbacks drive growth or decline away from homeostasis  Negative feedbacks attempt to restore homeostasis  Feedbacks work together to help control population size  They lead to changes in a population’s inputs or outputs  Feedbacks change with the analytical scale  Scientists study populations systems at different scales  The scale depends on the needed information  An individual population system can be analyzed  Think observing a group of orcas  How do they interact with their environment  How do they interact within their population?  A population interaction system can also be analyzed  Think observing a group of orcas and a group of fish  How do the two populations interact with their environment?  How do the two populations interact with each other? HUMANS AND ELEPHANTS IN AFRICA  Horton Hears an Endangered Species  The African elephant population is nearing extinction  There is significant elephant loss in places like eastern Africa  The decline is due to two anthropogenic factors  Humans are overtaking the African elephant’s habitats  Humans are overhunting the African elephant African elephant land loss poaching nearing extinction  Land Loss  The human populations of African countries have significant growth rates  These countries are less developed  So, their economies revolve around jobs like farming  In an agriculturally-intense society, more children means more workers  The kids work on farms and can help earn money for their family  This also means more food is needed for everyone to survive  As a result, more arable land is needed  This farmable land is repurposed from surrounding habitats  The natural savannas are turned to farmland or deserts  The animals that live in these habitats are forced out  Human conversion of elephant habitats has led to population decline  The elephants lose sources of food found in their habitats  They start dying from starvation, including their next generation  Their reproduction rates decrease in a vicious cycle  Less babies are born and less survive to adulthood  A positive feedback loop results  Loss of habitat leads to less food availability  Decreased food sources lowers the population  The more habitat lost, the lower the population drops  The net flux rate is negative  There are more elephant deaths than births  An increased output and lowered input tips the flux rate  National parks are an inadequate solution  They provide refuge to elephants but do not have enough space for them  The Tsavo National Park is in Kenya  The habitat has annual rainfalls less than 500 mm  Most of Kenya’s African elephant population lives here  The area is very dry and lacks dense vegetation  The conditions are not suitable according to scientists  Tsavo National Park needs 1,000 square miles of habitat for its elephants  Central and southern Africa have 20 total nature reserves  Only 7 of them meet this 1,000-square-mile requirement Families Humans Elephant Humans have more need food population convert kids to and money decreases land work farms The Farming Farming Elephant elephants brings food provides habitat is have less and money both lost resources Nearby Habitat's land is carrying turned capacity is arable lowered  Poaching  The agriculturally-based societies of African countries are not lucrative   However, the illegal ivory trade is very lucrative  Elephants have tusks made of ivory  A tusk is a long, extended tooth  Just like your teeth, elephant tusks are embedded in their skull  They contain nerve endings and hurt when removed  Hunters want this ivory  Ivory is a dense material made of dentine  Dentine is only found in tusks or teeth  Elephants are tranquilized or killed to extract the entire tusk  The poachers want the most ivory possible  As a result, they cut into the skull  The tusks are removed from the root  Poachers are often unconcerned with an elephant’s wellbeing  Incorrect tranquilizer doses are lethal  Improper cutting methods can kill a tranquilized elephant  Excessive or open wounds can lead to infection and death  The ivory demand is high  The material is sought after by many people  Ivory is durable and very easy to shape  Some believe it to have healing and protecting powers  People are willing to pay very high prices for the material  Ivory is becoming increasingly rare  Elephants are going extinct from excess poaching37  An elephant’s tusks do not regrow, just like your adult teeth  Mitigation  The Convention on International Trade in Endangered Species was held in 1989  Africa’s declining elephant population was addressed  CITES declared the species on the verge of extinction  They did not work to reduce habitat loss  To help decrease poaching, they banned the ivory trade  Exports of ivory from African countries became illegal  Ivory was confiscated and stored by governments  The ban caused a black market to quickly spring up  The ivory trade ban had made ivory less accessible  This drove up the demand since less was available  An increase in the demand increased the price of the ivory  The increased price motivated people to take up ivory poaching  Another positive feedback loop results  The scarcity of ivory increases the demand for it  The increased demand leads to more poaching for ivory 37   The elephant population declines, driving up ivory scarcity Poachers are Elephants motivated to are hunted get more for their ivory ivory tusks The price of The elephant ivory population increases decreases from scarcity  Negative Is Good  Negative feedback helps in regulating a population system  They can spur population growth to meet the carrying capacity  They can cause population reduction to meet the carrying capacity  The set point is when the population is at an environment’s carrying capacity  These feedbacks vary based on how many animals are in an area  The number of animals in a defined area is known as population density  An example is human population density  In the United States, it is measured as people per square mile of land  Population density feedback loops are universal  There are three types that will affect any population  They are shortage, selection, and society  Food Shortage  The first density-dependent feedback is food scarcity  A food shortage inevitably leads to increased death rates from starvation  Malnutrition discourages reproduction and decreases birth rates  There is a lowered net flux until the population meets the carrying capacity  At this point, the population is low enough to survive on the available food  The death rates decrease from increased food access  The birth rates increase as well  Natural Selection  The second density-dependent feedback is nature  A group of animals will be more likely to fall sick due to their proximity  Disease spreads faster in dense communities  Recall that, during the COVID-19 pandemic, the goal of social distancing was to space people out to avoid spreading a disease  Parasites can also spread through close proximity  Lice are parasites that feed on human blood  They can move to other people from hair-to-hair contact  In a tight crowd, lice can spread quickly from accidental contact  Disease and parasitism can cause an increase in illness and death  Social Systems  The third density-dependent feedback is social systems  Too few resources and too little habitat space causes friction within a population  Interactions between individuals in a population are intrapopulation interactions  A tightly-packed population will have more interactions  Some of these interactions will be competition38  Competition will often lead to injury and death  Population members might leave because of this  The emigration and death rates are higher  The birth rates can decrease from behavioral changes  The net flux becomes negative  The Hunger Games offers an excellent example of this39  A population of selected tributes is placed in an arena to compete for limited resources like food and weapons  An increasing lack of resources causes tension  Eventually, the arena becomes smaller, reducing the tributes’ habitat  Overcrowding raises tensions between tributes  The tributes have to fight for resources to survive Density-Dependent Feedbacks Increased social Predation interaction Parasites Disease Food shortage - RED SPRUCE  What is an ecosystem?  An ecological system includes all the biotic and abiotic factors of an area  This area can be a niche or small  An example is a tide pool  This area can also be extremely big  An example is a forest ecosystem  A larger ecological system scale makes analysis more difficult  A tide pool is relatively small  It has a few biotic and abiotic factors  The factors are interconnected but are not too complicated  This ecosystem contains on a few subsystems to analyze  An issue in this ecosystem can be identified quickly  A forest is enormous  It has many interwoven biotic and abiotic factors  The subsystems will have many overlapping layers  Pinpointing the cause of an issue is challenging 38 39  a lot of bigger more things to ecosystem factors account for  More fluxes will occur at a larger scale  When we looked at the Mono Lake system, it had only four subsystems  Still, each subsystem had influxes and outfluxes  There was even some overlap between the fluxes  A forest ecosystem has far more fluxes  Influxes are biotic, like plant births, and abiotic, like rainfall  Outfluxes are also biotic, like bird deaths, and abiotic, like nutrient use  Fluxes are often difficult to analyze  There will be inevitable overlap  There are many fluxes to account for  Spruce It Up  The red spruce is a conifer  A conifer is a tree species that reproduces via cones Red Spruce Quick Facts  Conifer are evergreens Grows needles  They do not lose their leaves in the winter  Conifers usually have needle-like leaves 300+ year lifespan  The red spruce is native to eastern North America Can grow in the shade  They grow in the Appalachian Mountains Used for pulp + paper  The mountains go from Georgia to New England  They also grow in eastern parts of Canada  Red spruces grow in low-elevation conifer forests  A conifer forest is many conifers that are growing together  There are conifer forests in Maine and eastern Canada  They follow the Appalachian Mountains  They also make up forests at higher elevations  Red spruces can survive at increased altitudes  However, they only make up 40% or less of these elevated forests  The Adirondack Mountains of New York have red spruce trees  Strange(r) Things40  In the 1980s, increasing amounts of red spruces were damaged or dead  The earliest reports of this inexplicable phenomenon dated to 1870  Scientists realized that acid rain was becoming more common  Normal rainwater41 has a pH between 5 and 6  Acid rain is rain that is way more acidic than normal with a pH around 4  The acidity is caused by air pollution  Water vapor combines with acidic pollutants 40 41   The combination leads to acid rain Emissions release The pollutants combine The resulting precipitation is acidic pollutants with neutral pH water an acidic rain The red spruce trees population was inexplicably declining faster  This acid rain could be damaging the red spruce  Scientists suspected that the red spruce was a canary in a coal mine42  The red spruce trees could be an indicator species of air quality  Their decline could be a sign that the air quality was poor  And Survey Says…  The Whiteface Mountain survey was done in 1964 and 1982  The mountain is a 1,483-meter peak of the Adirondack Mountains of New York  The survey data indicated that the red spruce tree was indeed dying quickly  Comparing the data showed a population decrease of nearly 70%  A survey of New York, Vermont, and New Hampshire found a correlation with altitude and red spruce deaths  There were more standing dead trees at increased elevations  We know that living conditions generally get worse as altitude increases Fewer soil Colder More air Less oxygen Fewer plants High winds nutrients temperatures pollution  Another survey of northern states covered nineteen mountains from New York to Maine  The data showed that the western parts had more standing dead trees  The western regions are closer to the Midwest  The Midwest has many large, pollution-emitting industries  They release air pollutants that harm surrounding areas  These effects include acid rain  The surveys helped to narrow down the potential causes  The White Face Mountain data showed that natural causes were not possible  Pests would have taken a short while to completely decimate the forest  The same applies to diseases, which would not have taken eighteen years  The three states data showed elevation had something to do with the deaths  More dead trees stood at higher elevations  The nineteen mountains’ data showed that trees died more frequently when they were closer to pollution  These findings pointed scientists in the right direction Forest Surveys Whiteface Mountain Data Three States Data 19 Mountains Data 42  Data was collected in A trend was seen in New Nineteen mountains 1964 and 1982 at the York, Vermont and New were surveyed from Whiteface Mountain peak Hampshire northwest-to-northeast Data showed A correlation of standing The standing dead tree nearly 70% of the dead trees with an increase count was higher on red spruce trees were gone in elevation the western side Natural factors like pests, Factors like colder Air pollution as a factor became pathogens, and drought temperatures, thin soil, and more plausible since Midwest were ruled out as air pollution became industries put emissions that affect plausible causes plausible causes western states like New York  Do you even OH-PEC(-CD)?  Scientists conducted experiments on red spruce trees  They observed that the cause of death was that the needles were succumbing to freezing injuries  This behavior is not normal  The red spruce can survive in colder temperatures  Scientists hypothesized that something was making the needles more sensitive  Air pollution and its byproduct of acid rain could be the cause  Scientists predicted that air pollution was causing needle freezing injuries  Observational Study  Environmental scientists decided to conduct a system analysis  System analysis is a form of observational study  To investigate the red spruce systems, the scientists could compare data from western and eastern systems  The goal was to look at how the measurements had changed  The first step in system analysis is to define the system  Biotic and abiotic factors make up the red spruce system  Biotic factors include the red spruce trees and surrounding flora  Abiotic factors include the soil and water  The inputs of the system came from the atmosphere  The outputs left the system through streams  The second step is to gather data  The scientists recorded information about the trees over a period of time  They recorded the number of trees in the system  The scientists also found the basal area of the system  The basal area of a tree is its trunk area at a certain height, usually four feet from the base  Researchers measure the circumference and find the diameter  Then, they calculate the area of the circle  Adding the values of all the trees give a systemic basal area  Basal area describe forest density  The scientists collected data about the system’s chemical composition  They conducted mass balance analyses  They found extra sulfate input and extra calcium output  Experiment  Scientists decided to conduct experiments on the calcium deficiencies  Many plants use calcium to resist the c