biodiversity past exam question

Why is random sampling and not systematic sampling used here?

You would need to go into studying details about cthe 2 techniques. eg.
Systematic sampling is simpler and more straightforward than random sampling. ... On the other hand, systematic sampling introduces certain arbitrary parameters in the data. This can cause over- or under-representation of particular patterns. Systematic sampling is popular with researchers because of its simplicity.

Ok. And I have read the text on sampling in my bio textbook, it says random sampling is used when the area under investigation is reasonably uniform or if the species are distributed in no clear pattern. And systematic sampling is used when physical conditions in the area you are investigating change-e.g you want to invesitage the change at the edge of the field where it becomes marshy.

So why exactly is random sampling used over systematic sampling in this particular example? I am having trouble deducing from the given info on 'sampling' in my textbook.