Changes in WHICH of the following factors will result in a change of an ecosystem's structure and composition?

  • A: nutrient availability
  • B: temperature
  • C: number of trees
  • D: light intensity

I got this question from an online "fun" quiz.

I understand that nutrient availability would affect the carrying capacity of an ecosystem. Temperature, if there was a big shift, could cause a change because some organisms would thrive and others would not. Light intensity affects the autotroph population.

But why would the number of trees not change it? I would think that if the number of trees changes, then the structure of the ecosystem would also have changed.

  • $\begingroup$ Yeah, I thought about it some more. The number of trees is not a factor, it IS part of the structure that might change if one or more factors is changed. $\endgroup$ – user1946283 Mar 10 '17 at 1:03
  • $\begingroup$ Well IMO, that's a bad question coming from your online quizz! As you said, C is not so much a causal agent than a change in itself. All the other agents are likely to affect the ecosystem by its structure and composition (whatever the definitions of structure and composition in this context). $\endgroup$ – Remi.b Mar 10 '17 at 1:09
  • $\begingroup$ Structure of an ecosystem deals mainly with species decomposition (Ref: On the Origin of Ecological Structure: web.stanford.edu/~fukamit/stokstad-2009.pdf). But I remember from one of old lectures, that species structure includes vertical stratification also (have no reference for it). $\endgroup$ – Tushar Mar 10 '17 at 5:39
  • $\begingroup$ Maybe the assumption is that if you remove some trees they will just grow back to whatever they were before due to factors like nutrient availability and temperature that dictate the ecosystem's composition, but that is ignoring that trees do have causal influence on ecosystem structure in addition to being part of it. Depending on the environment the trees may be part of a positive feedback loop that maintains certain conditions, and once you get rid of them those conditions will change. $\endgroup$ – Oosaka Mar 10 '17 at 7:34
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    $\begingroup$ I'd vote for E: all of the above. $\endgroup$ – RHA Mar 12 '17 at 7:29

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