Final answer:
The botanist and artist in the question who traveled and documented the American South in the late 1700s is likely John Bartram. John James Audubon, although a famous naturalist, was most active in the early 19th century and later contributed to ornithology and conservation efforts with his detailed illustrations in The Birds of America.
Step-by-step explanation:
The botanist and nature artist mentioned in the question who traveled across the American South in the late 1700s and recorded his observations of the land and native peoples, and who is also recognized for utilizing the concept of the biome is likely to be John Bartram. Although John James Audubon was a renowned naturalist and artist, his time period does not match that of the late 1700s, as Audubon was most active during the early 19th century. Instead, John Bartram (1699-1777) fits the timeframe and description better, having explored the American South and documented his findings.
John James Audubon, however, became famous later for his documentation of American birds in their natural habitat and his publication of the illustrious The Birds of America. Audubon's work contributed significantly to the fields of ornithology and natural history illustration and laid groundwork that influenced the environmental and conservation movements, leading to the eventual establishment of the Audubon Society, which actively participates in wildlife preservation.