Q4ITD - Campbell Biology

Question

(a) In the field, S. patens is typically absent from freshwater marshes. Based on the data, does this appear to be due to salinity or competition? Explain your answer. (b) T. angustifolia does not grow in salt marshes. Does this appear to be due to salinity or competition? Explain your answer.

Step-by-Step Solution

Answer

(a) As it can thrive at zero salinity in experimental freshwater marshes without competitive neighbors but has decreased biomass in the presence of neighbors, S. patens are often missing from wild freshwater wetlands.

(b) Due to salinity, T. angustifolia does not grow in natural salt marshes; it also does not grow in experimental salt marshes, even when there are no competing species. It does not grow in a greenhouse with greater salinity levels. 

Step 1: About the experiment

Salinity and competition affect plant distribution in an estuary is an experiment on S. patens and T. angustifolia. Observations on the ground indicate that Spartina patens (salt marsh hay) are the dominant plant in salt marshes, while Typha angustifolia (cattail) is prevalent in freshwater marshes.

Step 2: Explanation for ‘a’

Originally from North America's east and Gulf coasts, salt meadow cordgrass (S.patens) has been introduced to the west coast. It is a climax species of salt marshes, specifically the zone to the seaward of the high-water line, in the high marsh environment.

Step 3: Explanation for ‘b’

There are numerous channels of natural drainage and irrigation, reservoirs and ponds, navigation canals, and natural freshwater and wetlands that support T. angustifolia. Due to its clonal growth pattern and great competitive ability, it tends to develop monodominant stands in ideal conditions for growth.