Biophysical Interactions

Natural processes, also known as biophysical interactions occur naturally and enable life of all forms. Some processes are visible and easily noticed, such as weather characteristics and change within the atmosphere and its impacts. Some processes are less visible, yet they are no less important. When we consider the title of this unit, Ecosystems at Risk, it is important to think about the relevance of the topic and ask the question, is it worth our time? Well the short answer is yes. When discussing the importance of ecosystem management, different people will consider have different reasons for their answer. An interesting field of study and research that is starting to develop is ‘environmental economics’. Economists are attempting to put a dollar value on the essential ecosystem services that we often take for granted. So the question is, what would you pay for planet Earth?

Read this article from New Scientist and watch the associated TED talk regarding ecosystem services.

You may be familiar with the various biophysical interactions essential to maintain life, but it is likely you have not considered the monetary value of such natural processes.

Ecology introduction

Although the syllabus may state that we first must look at ‘biophysical interactions’, we are essentially looking at the basics of ecology, which of course is the study of living things and their interacting with other living things and their environment.

Watch the video below.

Read this introduction to ecology, note down the main points and then after reading, complete these questions:

1. Explain the biotic and abiotic factors that enable mould to grow your shower.
2. Identify the biotic and abiotic factors that see the Red Panda listed as a vulnerable or endangered species.
3. Identify and describe the characteristics of each level studied within ecology.
4. Reflect upon our field trip to the alpine ecosystem of Kosciuszko National Park, give one example of a population found within that ecosystem.

Read this article to complete the following questions:

1. Define the term species.
2. What is a binomial and why are they useful when studying various organisms?
3. Define the term population within an ecological context. Why is it sometime difficult to determine the size of a population?
4. How do communities and populations differ?
5. Create your own definition of the term ‘ecosystem’ based upon what is provided.
6. Create your own diagram to help you visualise the different ecological levels. Use the example given, but you are to use the feature the Kosciuszko National Park alpine ecosystem.

Skim read this article in order to complete the following questions:

1. Give the binomial and common name of the species featured in the article.
2. Undertake your own research in order to describe the characteristics of the term “critically endangered”.
3. Describe the physical characteristics of the species and include an photo.
4. Describe the location and extent of the population.
5. Describe the biotic and abiotic interactions essential for this organism.
6. Outline the nature of the various threats to this species.

1. After reading through this article define the following terms: Competition, symbiosis, mutualism, parasitism.

After reading this article, complete the questions below.

1. Define the term heterotroph and give two examples.
2. Define the term autotroph and give two examples.
3. Differentiate between a primary, secondary and tertiary consumers.
4. Copy down this diagram in your book.

Read this article and complete the following questions:

1. Define the terms ‘food webs’ and ‘biogeographical cycles’. Compare and contrast these two terms.
2. Describe how matter is recycled through earth’s ecosystems.
3. Copy down the diagram outlining the characteristics of an ecosystem’s energy flows.

Read through this article to complete the following questions:

1. What are the two types of autotrophs? Describe the characteristics of each.
2. Compare and contrast food chains and food webs.
3. Describe the characteristics of energy transfer between the different trophic levels.

Producers convert elements such as carbon, oxygen and hydrogen to usable inputs, that is, lifesaving organic compounds and sugars for food. For example, a worm eats decaying leaf litter and converts the nutrients received into manure which is added to the soil.

Most of the available ‘food’ or nutrients for any ecosystem are found in the top layer of soil and leaf litter. Hence the biomass or biological mass of food available is in the lowest trophic level.

The recycling of nutrients and the resultant energy loss perhaps explains why there are numerous small plants and insects at the lower trophic levels and many herbivores plus fewer carnivores and less energy to support them at a tertiary trophic level. The lower trophic levels have a surplus of nutrients and energy where as there is a deficit at higher levels.

An ecosystem is a system with inputs and outputs and a balanced or steady state when the equilibrium of inputs and outputs is maintained in a certain environment. When the flow of nutrients entering the system is altered because of a human change or such climatic disasters as a drought, the whole system is affected and some species become extinct or rare while others adapt and flourish.

(Excel HSC Geography, Pashley, 2003).

Energy Flows and Primary Productivity

Read this article to complete the following questions.

1. Define the terms ‘productivity’ and ‘biomass’.
2. Outline the characteristics of ‘gross primary productivity’ and ‘net primary productivity’.
3. How much of the sun’s solar energy ends up as net primary productivity?
4. Observe the .gif image below, describe the spatial distribution of areas of high Net Primary Productivity. What types of biomes are present in the locations with extremely low Net Primary Productivity?
5. What percentage of energy is transferred from one trophic level to the next?
6. Why is energy transfer inefficient?
7. Why are ecological pyramids useful when attempting to identify the flows of energy within an ecosystem?

(Animation credit: “Net primary productivity,” by NASA, public domain.)

Watch the video below

After watching the video above, complete the questions below:

1. Complete this sentence, “species richness is…”
2. Why is there less species richness near the poles?
3. Define the term ‘species diversity’.
4. Why do you think that ecosystems with more species diversity more stable?
5. What factors shape community structure?
6. Define and give examples of ‘foundation’ and ‘keystone’ species.

Create a table outlining the characteristics of the following cycles and describe what roles they each play within an ecosystem.

Complete the Google Forms quiz below. You will need the broadsheet from the 2012 HSC as the quiz includes 20 multiple choice questions from this exam.