Nutrient supply is an important factor influencing primary productivity. A class of Biology 306 students was shown a dataset in which the addition of fertilizer significantly increased productivity in a forest, then was asked a discussion question to assess their expectations of what the results would look like to a person who observed the system before and after fertilizing. Which of the following suggestions seem plausible to you? Select all that apply.
a) because forests are generally bottom-up-regulated, the addition of nutrients would necessarily increase the growth of all plant species in the forest by about the same amount.
b) because forest plants differ in both their nutrient requirements and their tolerance for low supplies, some species would grow much better while others might grow a bit better, or show no difference in growth.
c) some species may have been present only as seeds before nutrient addition (i.e. their seeds disperse in very easily but cannot grow due to competition from established plants for nutrients); these species will grow explosively and become dominant after addition.
d) only the most competitive-dominant species present before addition will be able to take advantage of the extra nutrients.
e) because forest plant species differ in life-history strategies, those more able to increase abundance (i.e. with higher rmax values) should be the ones most likely to outgrow neighbours.
Nutrient supply is an important factor influencing primary productivity. A class of Biology 306 students was shown a dataset in which the addition of fertilizer significantly increased productivity in a forest, then was asked a discussion question to assess their expectations of what the results would look like to a person who observed the system before and after fertilizing. Which of the following suggestions seem plausible to you? Select all that apply.
a) because forests are generally bottom-up-regulated, the addition of nutrients would necessarily increase the growth of all plant species in the forest by about the same amount.
b) because forest plants differ in both their nutrient requirements and their tolerance for low supplies, some species would grow much better while others might grow a bit better, or show no difference in growth.
c) some species may have been present only as seeds before nutrient addition (i.e. their seeds disperse in very easily but cannot grow due to competition from established plants for nutrients); these species will grow explosively and become dominant after addition.
d) only the most competitive-dominant species present before addition will be able to take advantage of the extra nutrients.
e) because forest plant species differ in life-history strategies, those more able to increase abundance (i.e. with higher rmax values) should be the ones most likely to outgrow neighbours.
