cory.ok said:
the logistical population model relies on having a relatively small system where you can ignore many factors. just like the exponential model, over time it will fail becasue it ignores variables. keeping in mind that the logistical model was derived from the exponential model because it didnt provide adequate predictions over time. we have to do the same thing for the logistical model if we want to mode the entire planet over a length of time thats more than a few years. we know that environmental degradation is happening and when we factor it into the equation carrying capacity is no longer a constant through time, its also a rate which will probably look somewhat like -e^x, making carrying capacity look something like K-e^t on your graph im not an ecologist but it seems pretty evident that as environmental degredation occurs, the environment can sustain less people, not the assumed constant amount, unless we can stop environmental degredation our population will continually decrease along with the carrying capacity. and after a little bit of research i found that, yes carrying capacity must be augmented for many systems |
You are right. Carrying capacity is not a constant value. It's always a dependant value. It depends on various factors. But it mainly depends on resources (food, water, space, etc.). In certain populations K can change from one year to another. Actually that model (the carrying capacity one) is only valid in a lab with controlled conditions.
Nevertheless it normally adjusts quite well to real and complex populations. But we have to take into accounts that humans are really a metapopulation. So the model should be applied to continents or countries. I accept that this model is quite limited to the complexity of the human population. But we can expect the human population to stop growing and get stable depending on the availability of resources (which is the main pillar of the K theory).
