Ecology, chapter 45 and 47

1. Briefly outline section 45.4
I. Density- Dependent Limiting Factors
a. Limiting Factor- Any environmental factor that- by its decrease, increase, absence, or presence- limits the growth, metabolic processes, or distribution of organisms or populations.
b. Carrying Capacity- The maximum population of a particular species that can be supported indefinitely by a given habitat or area without damage to the environmental.
c. Logistic growth- is a pattern that shows how carrying capacity may affect population size.
d. density- dependent controls- reduces the odds for individual survival.
e. Density- independent factors- Any factor limiting the size of a population whose effect is not dependent on the number of individuals in the population.
2. Briefly summarize the 3 survivorship curves and offer an example of each.
Curve 1 reflects high survivorship until fair late in life, then large increase in death. For example, female elephants give birth to four or five calves in her lifetime and devote several year to parenting each one. Curve 2 reflects a constant death rate at all ages. Examples are birds, lizard, and other not so large animals, such as monkey. Curve 3 reflects a death rate that is significantly high. Insects are the example for curve 3 because after they produce their offspring, they will die.
3. Briefly describe what the age structure diagram would look like for each of the following populations:
1. For the population that is undergoing negative growth, the age diagram structure would be skinner compare more to other age structure diagram. The reason why it’s skinnier than other age structure diagram is because during negative growth, there are less pre-productive years, than post-productive years.
2. If a population with nearly no growth, the age structure diagram would look more balance than the negative growth one. The reason because there are slightly more pre-productive years than post productive years, so it makes the bottom longer, and the top slightly narrower.
3. If a population growth rapidly, the age structure diagram would have less post- productive years than pre-productive years.
4. If a population growing slowly, the age structure diagram would look like a pyramid. There will be a lot more pre-productive years than post-productive years.
D. The ecosystem phase of the nitrogen cycle starts with nitrogen fixation. Bacteria convert gaseous nitrogen in the air to ammonia and then to ammonium, which is a form that plants easily take up. By ammonification , bacteria and fungi make additional ammonium available to plants when they break down nitrogen-rich organic wastes and remains. By nitrification, bacteria convert nitrites in soil to nitrate, which also is a form that plants easily take up.