For the Aztecs, the enviroment was more benevolent. The aztecs inhabited Central Mexico which is a highland area where temperatures are mild. Soils are also very fertile because they are volcanic. The biggest challenge they had to face was precisely the active volcanoes that sorround the Central Valley of Mexico.
For the Mayans, the enviroment was more unforgiving. They inhabited a lowland tropical jungle with high humidity and temperatures all-year round. The soils were not very fertile either.
It has been theorized that the Mayan civilization disappeared because of deforestation, which led to a rise of temperatures and a general worsening of enviromental conditions.
Colonization ruptured many ecosystems, bringing in new organisms while eliminating others. The Europeans brought many diseases with them that decimated Native American populations. Colonists and Native Americans alike looked to new plants as possible medicinal resources.