Zooplantman is undeniably the expert here, but it is interesting to see North Carolina's lush, grassy exhibit as the enclosure there has 7 elephants on 7 acres and so it would take a long time for the pachyderms to wear away the exhibit and turn it into a dustbowl. Also, the interior of North Carolina is not as arid as southern California.
Nashville's 3-acre exhibit has in the past only had 2 elephants and at the moment I believe that there are 4 elephants there, so the massive size of these habitats must play a vital role in maintaining the lush, green atmosphere. I admit that when I go on long summer road trips and visit over 30 zoos within a couple of months it is thrilling to gaze upon elephants trampling through grassy fields. Speaking in purely aesthetic terms the dusty, sandy, tiny yards still found in many urban zoos simply cannot compete with the large, grassy habitats that are the best of America's many elephant exhibits.
With certain areas of the U.S., especially east of the Rockies, there is way more rainfall and humidity; thus, greener more lush surroundings. Remember, LA and San Diego both are known for their Mediterranean climate. And with virtually no rainfall during the entire summer on average, as compared to Nashville and North Carolina, or most anywhere else down south for that matter, there is no way to even compare the lush possibilities of one area to another. Though lack of humidity is why so many people flock to places like California, Arizona, and Nevada, seeking warm and dry temperatures.
