Unit 1 Evaluation

Table of Contents

Chapter 1

• Understanding Our Environment
  
• Issues Facing the Environment
  
• Human Impact on the Environment
  
• Using Science to Study the Environment
  
• Sources of Environmental Studies
  

Chapter 2

• Environmental Systems
  
• Basics of Life
  
• Importance of Energy
  
• Makeup of Ecosystems
  
• Biochemical Cycles
  

Chapter 5

• Land Biomes
  
• Marine Biomes
  
• Biodiversity
  
• Environmental Threats to Biodiversity
  

Chapter 3

• Evolution
  
• Population Growth
  
• Interactions of Species
  
• Interspecies Dynamics
  

Chapter 1

Understanding Our Environment

    There are many challenges but also many rewards for taking the time to understand our environment. Study of our planet and all the diversity of life should make us realize how fortunate we are to be alive. Taking advantage of the diversity of the planet and the technology we now have allows us to study our environment scientifically. With the challenges facing the human race and all animal species due to destruction of our environment it should be a concern for all humans to learn what they can about protecting our planet.

Issues Facing the Environment

    One of the largest issues currently facing the planet is the population explosion of humans. Currently there are close to 7 billion people on the planet, and a large percentage of the population is not having their needs adequately met. This comes in various forms, from having enough food to feed the population, and having the energy sources to support life, and access to clean water. There are also issues with air quality, loss of unique species due to human interference, and dwindling food supplies.

    Many people have already taken on the task of studying the environment, and thanks to their efforts there are now many ideas and plans in place for controlling many of these problem areas. Advances in technology have allowed for reduction in pollution, discovery of immunizations and cures have reduced many types of disease, and there have been advances in finding sources of renewable energy to reduce our reliance on finite fossil fuels.

Human Impact on the Environment

    Any study of the environment must now include the impact of humans. As the human population has grown, we now live in many of the environments the earth has to offer. Unfortunately humans have often neglected to take care that their actions would not have harmful effects on the environment. There are many causes for this, from ignorance to greed, but they must all be accounted for in any study of the environment. The United States if one of the countries primarily responsible for this, as we throw away 160 billion tons of garbage every year. There is no way the earth will be able to keep up with the lopsided taking of and disposal of resources and be able to sustain life.

Using Science to Study the Environment

    Since the many environmental issues facing the earth are complex, it takes a scientific approach to truly study the environment. It is through this deliberate approach that demands that nothing be taken for granted, that we learn how the environment works. Being able to reproduce the same results then allows us to form theories, which in turn can be used to predict future behaviors. Predicting and modeling environmental behavior will allow us to be better prepared to face the future. It may also help us avoid potentially disastrous situations that would have negative impact on the planet. The scientific method has lead to paradigm shifts in how we explain the world around us. Instead of attributing the formation of the environment to mythological events, scientists can now point to repeatable natural causes that influence and shape the features of our planet.

An example of applying Environmental science to a known issue (Principles of Environmental Science, p. 4)

Sources of Environmental Science

    There are many sources for why we study the environment. Some of the triggers that have lead to the rise of environmental science include the rise of resource waste, rising concern about preserving the environment, and the sharp rise of pollution in the Industrial Age. Together these movements have provided the primary sources for why we rely on environmental science. The hope is that this will lead to enough social progress that all people, not just the wealthy, will be able to enjoy the rich diversity the earth has to offer us.

Chapter 2

Environmental Systems

    Our environment is composed of many systems. In regards to the environment, a system is generally used to describe a network of interdependent components, with materials and energy moving from one component to another. There are various ways to describe the systems. The majority of systems in nature are regarded as Open systems, that is they receive input from outside of the system, and have outputs that leave the system. There are also Closed systems, but those are rare systems that receive no input or have output outside of themselves.

    Systems have can Positive or Negative feedbacks. Both of these types of feedbacks refer to whether the feedback leads to growth or a decrease in the system. For the most part, negative feedback tends to keep an overall system more stable. Systems of course can be subjected to disturbances which can cause dramatic fluctuations. This can cause the system to undergo a state shift, where the system will not recover to the same levels it was at pre-disturbance.

Basics of Life

    These systems are all compromised of various forms of life. All life is made up of matter. Understanding that life is made up of matter, it is easier to understand that matter does not disappear, rather it is reused and recycled. Breaking it down further, matter is composed of elements. Oxygen, Carbon, Hydrogen, and Nitrogen make up 96% of the mass of most life. Understanding how these elements work of course lead to better understanding of how environmental systems work. Cells are the most basic form of life. Some organisms consists of single-cells, while larger life can consists of trillions of cells working together. Each of these cells are open systems that work with neighboring cells to control the larger organism they make up.

A simple display of an environmental system (Principles of Environmental Science, p. 28)

Importance of Energy

    Without energy, there would be no life. Energy is what provides cells with the ability to function. There is Kinetic energy and Potential energy. Kinetic energy is contained in moving objects, such as wind or moving water. Potential energy is stored energy, such as that same water behind a dam. There is also energy provided by chemicals, and heat is another energy source. These energy sources vary between being high-quality sources of energy or low-quality. Energy is governed by the laws of thermodynamics. The first two laws of thermodynamics state that energy cannot be created or destroyed under normal circumstances. The second law states that each time energy is transferred or transformed, there will be less energy to work with. These laws can be seen in action every day in every environmental system we observe.

    The primary source of energy for our planet is the Sun. Without the sun there would be no life on earth. The solar energy from the sun is captured by plant life on Earth. The plants then use a process called photosynthesis to convert that light to energy. This energy forms the basis for life on earth. The plants use the energy to grow. Other life then feeds on those plants. In turn other life preys upon the animals that eat the vegetation. When those animals die, their body decomposed into basic elements, which are then recycled and used again.

Makeup of Ecosystems

    Ecosystems are composed of both biological communities, and the physical environment. From there you can break down ecosystems further. One way that is down is be breaking an ecosystem down into trophic levels. Each trophic level has its own unique species that populate it. It begins with producers, which are primarily plants. Each trophic level will feed on the trophic levels below it. Some species will feed on all trophic levels, such as parasites or scavenger species. Each level you go up in a trophic system will have fewer and fewer members of the system, as each trophic system only transfers about 10% of its energy to the next higher level.

Biochemical Cycles

    All of the elements that life is made up of are on a constant cycle through our planet. As organisms break down and decompose, the matter that makes up the organisms is used again. For example we still use carbon that has been around for millions of years, but we use it as coal or oil. When we use it, it breaks down into basic elements, and will then be used to create new matter, although it may not be apparent to us in a single lifetime.

    One of the easiest to examine biochemical cycles is the hydrologic cycle. This is the cycle of water through our biosphere. Our primary source of water is the oceans. Solar heat evaporates that water, and wind blows the water vapor over dry land. There it comes down to the earth in the form of rain or snow. Eventually the water will make its way to lakes or rivers, and journey back to the ocean to start the cycle over.

    There are many other biochemical cycles that help make life possible. These include the carbon cycle, the nitrogen cycle, the phosphorus cycle, and the sulfur cycle. Some of these cycles can take place over millions of years, such as the phosphorus cycle. These cycles are all needed by our environment in order to produce life.

Chapter 5

Land Biomes

    There are many different types of environments that make up our biosphere. We can divide these environments into communities knows as biomes. Biomes are consistent across the planet, so we can predict what kind of biome will most likely be present based on variables such as temperature and precipitation levels. The biomes can be roughly grouped into Tropical, Temperate, Deserts, and Tundra. Each of these biomes have unique characteristics that contribute to our overall planetary system.

A chart showing common biomes based on temperature and precipitation (Principles of Environmental Science,  p. 98)

Marine Biomes

    Along with land biomes, there are also biomes spread through our oceans and water systems. These are referred to as Marine biomes. While marine research is lagging far behind terrestrial studies, it appears that marine biomes are as widely varied as land biomes. The marine biomes also have their own unique trophic systems, with multiple levels like terrestrial biomes. Generally the levels of ocean biomes are defined by their depth and proximity to land.

Biodiversity

    The land and marine biomes all contribute to what we call biodiversity, or variety of living things. There are three types of biodiversity considered essential to preserve our current balance in ecological systems. These are Genetic Diversity, Species Diversity, and Ecological Diversity. As each of these systems form symbiotic relationships, they continually contribute to the vast variety we find in almost all species of life on earth. Biodiversity is helpful in helping ecological systems better endure shifts in the environment. A variety of species in each biome help maintain the balance between the trophic levels. If biomes were limited to just a few species, a loss of species could have devastating effects on the other trophic levels.

Environmental Threats to Biodiversity

    Unfortunately biodiversity is under a constant threat. Most of the threat can be placed at the feet of humans. Extinction is a huge threat to biodiversity. As mentioned previously, the loss of any one species can have huge ripple effects in a biome, but since the beginning of the Industrial Age thousands of species have become extinct due mostly to man-made causes.

    These man-made threats are commonly summarized with the acronym HIPPO, which stands for Habitat destruction, Invasive species, Pollution, Population of humans, and Overharvesting. Of these Habitat destruction poses the most immediate threat to our current biodiversity. As humans domesticate more land for their use, the previously existing habits are destroyed, many times permanently. Life that lived in these systems could be unique, and when they die off in that system, they then become extinct. By careful study of the environment, we can raise more awareness about the damage being doing to various biomes, and attempt to curtail more damage before we wipe more species out.

Chapter 3

Evolution

    A large share of credit to our biodiversity is owned to Evolution. Evolution is a widely accepted theory that in a basic form states that adaptation and natural selection account for the species we have today. The individuals of a species that have best been able to adapt and produce offspring are the species that have survived. Over time these adaptations may have led some species to have very little resemblance to their ancestors. These adaptations that species have developed also limit them to where they can now live. Species that require moisture and warm temperatures would not be able to survive their habitat becoming a frozen tundra.

Population Growth

    All species on earth have the potential to increase their population by incredible rates. However this does not occur without outside influence. If a species were to procreate with nothing to check their population, the earth would be overrun by that species relatively shortly. However populations are kept in check by scarcity of food, disease, predators, and resource competition. This helps to keep biomes in balance. Often times mankind has introduced a variable into the environment that can cause a population to grow unchecked.

A chart showing the relationship between rabbit and lynx populations (Principles of Environmental Science, p. 64)

    For instance in Hawaii new settlers wanted to cut down on the number of rats on their sugar plantations. The idea was proposed to introduce the non-native mongoose into the population to keep the rats in check. Unfortunately not enough fact checking was preformed beforehand. Mongoose are active during the day, and the rats were nocturnal. Instead the mongoose set out to eat other native life, and Hawaii now has some of the highest number of endangered species on their island due to the mongoose population being out of control. (http://www.perlgurl.org/archives/2006/05/the_mongoose_a_maui_menace_1.html)   

Interactions of Species

    Each biome can contain thousands of species of life. These species form communities, and all the communities in a system are sometimes referred to as biomass. The communities over time began to form symbiotic relationships. These relationships are important as they promote stability across habitats. When there is stability in a habitat the species there can better resists stress or disturbances.

Interspecies Dynamics

    While biomes naturally try to become stable, this does not always happen. As species are introduced or die out due to natural or man-made causes, the communities that form different habitats all change over time. While we may not have life spans long enough to see all the changes that can occur in a biomes, these can still happen relatively quickly within a few generations of life depending on how drastic the changes to the community are. Occasional changes in communities can help promote the survival of the particular habitat over time. While evolution seems to handle this job best, we now have a responsibility as the dominant species on the planet to try and preserve natural habitats for all species, and let evolution work naturally with as small a human footprint as possible.


 

Singer Predator-Prey Simulation

    This is my presentation of the Predator-Prey simulation for Biology 105. The purpose of this simulation is to show the relationship between the population of rabbits (prey) and lynx (predators) over 20 generations.

    My hypothesis for this simulation experiment is that as the rabbit population grows, the lynx population will also grow. I would expect that a balance would eventually be reached that supports a steady number of lynx and rabbits without any uncontrolled outside factors such as drought or disease.  

    I begin the simulation by gathering and creating the needed materials. Using a piece of yellow poster board, I marked off an area that was 12"x12". I then printed out and cut 300 1" square rabbits, and 1 3" square lynx.

Rabbit Generation 1

First Generation Lynx

    The experiment beings with 3 rabbits populating the simulation. The first generation lynx was able to capture a single rabbit. The parameters of the simulation indicate that for a lynx to survive to the next generation, it had to capture at least 3 rabbits. This meant our initial lynx did not survive. The remaining rabbits from each generation will then double in number. This means that for the second generation of the simulation, there will be 4 rabbits for the lynx to try and capture.

    Using these parameters it took until the 5th generation for a lynx to survive. The lynx survived by capturing 3 rabbits. This also means that the lynx was able to produce offspring, as the simulation states that for every 3 rabbits captured, a lynx will produce one new lynx.

First Lynx Survivor

Reduced rabbit population of Gen 8.

    The population of rabbits and lynx then continued to grow over the next few generations. However in Generation 8, something interesting occurs. While 9 lynx successfully live and produce offspring, there are only 7 surviving rabbits. In Generation 9, 17 lynx have to try and survive off of only 14 rabbits. None of the 17 are able to get enough rabbits to survive, and in Generation 10 the cycle starts over with only 1 lynx and 3 rabbits.

Large rabbit population of Gen 7.

    In generations 11-20 we see the same cycle being followed, although this time we have new peaks with 140 rabbits (Generation 19) and lynx at 43 (Generation 20). As with the previous cycle however, the reduced rabbit population from the previous generation cannot support the increased lynx generation, and 34 of the 43 lynx starve in Generation 20.

    The Predator-Prey simulation appears to disprove my hypothesis that a stable balance would be reached between the rabbit and lynx populations. Instead, both populations would increase and then quickly decrease. For the rabbits this could be seen as the population grew too large and their food (vegetation) would become scare, and for the lynx too much competition along with fluctuations in the rabbit population would lead to sharp decreases in their populations.

    This was without the simulation taking into account other variables that could also have heavy influences on the population of both species. Disease is one example that would affect both populations, regardless of which one actually was carrying the disease. Drought would be another example that would affect both populations. Not factoring other animal species into the simulation would also affect outcomes, as there would be more competition for the resources provided in the simulation zone. The roaming pattern of lynx could also affect the outcome, as environmental issues could cause more neighboring lynx or rabbits to move into the simulation zone. Of course there's also the effect that Man would have on the simulation, with pollution, hunting, and destruction of the environment all factors that would change the outcome of any simulations.

    One outcome to consider would be if the lynx were exterminated, perhaps by overhunting. In this case the rabbit population would continue to grow, but would most likely also suffer a sharp decrease. The large population would not be something the producers of the zone would be able to support, and the vegetation would be severely reduced. This would lead to a sharp decline in the rabbit population after an initial spike. It might take several generations for the vegetation to recover enough to support the rabbit population again.

    The pattern that seemed to occur in the simulation was that as the rabbit population increased, the lynx generation would also increase. This would reach a peak level however, and then both populations would quickly drop down. There would be about a one generation lag between when the rabbit population would drop and the lynx population would drop. So at a time when you might think the lynx population was healthy and strong, would usually indicate there was about to be a severe drop in the population due to not enough food being available. It would then take the lynx several generations to start to increase in number again.

A true apex predator displays how rabbit hunting is done.

    What we learned from this experiment is that while we can attempt to chart out projections for different animal species, it's much more difficult to project due to so many random factors being present in real world conditions. It does give us a good example though of how delicate the balance in nature is, and we should always pause before taking action that will impact the environment.