Ecological Complexity


Ecosystems are complex things. The diagram above is mislabeled. It is a simply diagram of a complex ecosystem. To better understand how we might try to understand complex things, it helps to work on a real one.

This time I want you to think about a bounded physical space. It could be your house, your backyard, a field next to your house, a nearby pond, your car, etc. — something that you can actually see all at once. Now think about it as a system. Simplify this system into the important parts and then diagram a material flow (inputs, outputs, internal cycles). Pick either a) water or b) carbon. If you choose carbon and don’t know too much about what carbon is and where it comes from, look at:

This may be more than you need to know… so focus on what you need to know about carbon. Try to keep it simple. Try to indicate which are more important processes (larger flux) and which are less important. Think about the time frame that you are considering the diagram to represent. EMail me the diagram. Now tell me what is hard about this question. What do you not understand?


Monika’s Garden:



Ian’s Water:



Michelle’s Pond:



Matt’s Compost Bin:


5 Responses to “Ecological Complexity”

  1. Tamar Bouchard says:

    In thinking about my car as a system that runs on and interacts with carbon I can see the obvious input of gasoline, which is processed carbon filled fossil fuel, and the engine compression that converts the liquid carbon filled gasoline into the output gaseous carbon laden exhaust that is then released into the atmosphere. I can also see that my car is composed of carbon rich components, such as the tires, plastic and carbon fiber parts. I can also see that my car is directly converting carbon from the land based fossil fuel into the atmospheric carbon that is creating all of the problems associated with global warming.

    I am not sure what I do not understand about this question, because there is always more to know. It would help if I understood what happened in the internal processes more. I also want to know more about how we are carbon based life forms and what that means. I worked in an environmental testing lab for a couple of years and we tested leachate from disgusting places like landfills for nitrites and nitrates, so I understand that these are good and also bad if there is too much of them, certainly the leachate was not particularly pleasant to deal with in and of itself.

  2. Matt Sayre says:

    The diagram I completed represents my backyard compost bin. It should include an additional box representing human manipulation (or manual turning) of the compost materials regularly, but for accuracy sake I did not include that recommended step since the truth is we almost never complete this step which is recommended to help advance the composting process. Instead, we just keep adding to the pile and then withdraw composted materials from the bottom of the bin via an access panel typically for use filling holes in the yard as needed. We typically do not use our compost for our own garden. We started our pile by purchasing an empty black bin, adding and initial load of carbon in the form of leaves and nitrogen primarily in the form of food scraps, and then spraying water from our hose into the pile then letting natural rainfall continue to add water to the pile to maintain its moisture. Our pile was pretty loose when we first started it and more air enters the pile when we remove compost from the bottom of the bin, but our pile has become quite compacted so air (oxygen) does not enter the pile very easily which hinders the micro and macro organisms that are decomposing the materials so our composting process happens slowly. We should add more oxygen to the system by turning it more frequently. The sun warms the bin and the materials inside heat up as microbes do their work decomposing the materials. The warmth provided by the sun (solar radiation) helps raise the temperature within the pile to a high enough amount so that specific microorganisms requiring such high heat can actively contribute to the decomposition process. This decomposition process results in the production of carbon dioxide and water. The compost of soil produced can be withdrawn by people for use replenishing nutrients to gardens or lawns. We use ours for our sandy yard. I would estimate that 50% of the organic material inputs into the system are from within 300 feet of the pile and another 50% come from non-local sources like food from the grocery store. The most challenging thing for me to understadn is balance within the cycle. How much carbon, nitrogen, water, oxygen, solar radiation, etc. is needed and when? Also, at a more macro level if I keep all the organic materials that grow on my property on my property and then add more materials in the form of food scraps will I be creating an imbalance over time with too many nutrients? This will never happen however becuase we do send leaves to the Intervale for composting and also have trees removed from the property occasionally, so the net effect will probably be a nutrient degradation over time due this significant removal.

  3. Anonymous says:

    My diagram represents the annual cycle of a pond located in a nearby woodlot. The pond is located alongside one of the logging roads. There is a culvert by the bridge which directs the flow under the road and into a brook. I wrestled with how to account for some of the human inputs into the system, particularly a man made catwalk that was built by Ducks Unlimited. Its a wooden framed structure. I omitted it from my diagram because it isn’t part of the natural systems, which I focused on. What’s difficult about this question for me is identifying the processes associated with the pond. I realize it is not like an ocean, so when I reviewed the reading on the carbon cycle, I wondered what, if any role, does a small pond play in this process? My guess is that it doesn’t. I also wondered if the difference between the composition of fresh water and ocean water changes the processes within the water cycle. The challenge for me is applying the readings to real life situations. I like this challenge, but I wonder if I am getting it, or am I simplifying it too much?

    posted by Michelle

  4. Ian Raphael says:

    My diagram represents the system of how water comes in and exits my home. Water comes from a well that is connected to the intricate groundwater system that is support through the general water cycle. Water is driven through evaporation and weather systems. Groundwater is also driven from mountain run-offs.

    The septic tank is the mechanism that treats the water output of my house. Water is filtered out and either evaporated, absorbed by plants, or added to groundwater. The waste material is also slowly integrated back into the system which provides nutrients that support the surrounding ecosystem.

    The time frame of my system is continuous. There is no real product that is taken out of the system. My house just diverts water in, then right back out again.

  5. Monika says:

    The time frame I’m considering is one growing season. The bounded physical space I’m considering is a garden, that has naturally occurring inputs: water, carbon dioxide, sunlight. It also has human inputs: seeds, fertilizer, additional water if needed. The outputs include intended outputs (vegetables) but also unintended outputs: weeds, run-off, oxygen. Some of these outputs are re-cycled into the system: water, oxygen, nutrients. Some outputs leave the system permanently: the carbon, water, and nutrients that go into the vegetable and weeds, and whatever water run-off carries out of the garden. The carbon inputs come from carbon dioxide, fertilizer, soil. The carbon leaves the cycle through the vegetables, weeds, and organic materials in the run-off.

    The pieces that I’m missing here: the relative amounts added, converted, lost, and recycled. Varying amounts of rain, sun, fertilizer would affect these proportions.

    Photosynthesis, respiration, decomposition, evaporation are also taking place in the system but I couldn’t figure out how to diagram them with my limited diagramming skills. In the below diagram, I put (C) under all in the inputs and outputs that contain carbon, so that the carbon could at least be traced.

Leave a Reply

You must be logged in to post a comment.