Chapter 29, Problem 8TYU

SCIENTIFIC INQUIRY

INTERPRET THE DATA Ihe feather moss Pleurozium schreberi harbors species of symbiotic nitrogen-fixing bacteria. Scientists studying this moss in northern forests found that the percentage of the ground surface“covered” by the moss increased from about 5% in forests that burned 35 to 41 years ago to about 70% in forests that burned 170 or more years ago From mosses growing in these forests, they also obtained the following data on nitrogen fixation:

(a) Use the data to draw a line graph, with age on the x-axis and the nitrogen fixation rate on the y-axis.

(B) Along with the nitrogen added by nitrogen fixation, about 1kg of nitrogen per hectare per year is deposited into northern forests from the atmosphere as rain and small particles. Evaluate the extent to which Pleurozium affects nitrogen availability in northern forests of different ages.