Deciduous Trees in the South

[AnTonY]

I've read through lots of discussions in another forum about how deciduous tree-heavy the South is compared to other subtropical regions. Just one of the many examples here:
http://www.city-data.com/forum/weather/1789938-why-does-inland-us-south-look.html

Such discussions inspired me to do my own research on the matter. As a result of such research, I am now coming to the conclusion that the presence of deciduous trees in the South has nothing to do with climate, but rather, is a result of geographic/geologic technicalities.

For one, places in East Asia at similar latitudes to the South are entirely broad-leafed evergreen, even southern South Korea, which sees average lows below freezing in winter. This kills the notion of "extreme cold" limiting decidious trees in the South (especially as many native evergreen species of the region can handle single digit Fs):
https://en.wikipedia.org/wiki/Southern_Korea_evergreen_forests
http://www.worldwildlife.org/ecoregions/pa0439
https://en.wikipedia.org/wiki/Yeosu#Climate

Furthermore, there is a proven inverse correlation between the evergreeness of a landscape, and the pH of the soil; the more evergreen the landscape, the lower the soil pH. Even within the South, areas of the region with richer nutrient soils (and thus higher pH), have more deciduous trees compared to areas with more nutrient-poor, acidic soils:
https://en.wikipedia.org/wiki/Evergreen#Reasons_for_being_evergreen_or_deciduous

Lastly, the North American continent is such that the humid tropic forests are cut off from the humid subtropics, by the Gulf of Mexico,and the Mexican desert; being that it is a continent that extends far north, it also has the cold winter areas that give rise to a high deciduous tree stock. As a result, it just so happened that the trees in the South were deciduous trees, as that is what much of the stock available was. This can be proven by seeing that even tropical South Florida has native deciduous trees:
https://en.wikipedia.org/wiki/Taxodium_distichum
https://en.wikipedia.org/wiki/Acer_rubrum

As a result of all this, I feel that deciduous trees in the South (especially in coastal regions) are simply a matter of soil/geographic technicality, as well as chance (aka, succession colonizers), rather than climate (even with the fact of cold snaps).

 

[nitsua0895]

I've always wondered this as well. Here in south/central Alabama there are tons of decidious trees, yet Magnolia trees and Live Oaks(to name a couple) thrive here. I really hope people will begin to plant more evergreen trees because a large, beautiful Live Oak makes me feel like it's the middle of summer no matter time of year it is.

[AnTonY]

19 hours ago, nitsua0895 said:

I've always wondered this as well. Here in south/central Alabama there are tons of decidious trees, yet Magnolia trees and Live Oaks(to name a couple) thrive here. I really hope people will begin to plant more evergreen trees because a large, beautiful Live Oak makes me feel like it's the middle of summer no matter time of year it is.

Yep, I've always had my suspicions that the decidious trees were there just because they were the trees that happened to grow and colonize that area, rather than that area being too cold for evergreens. Check the pH of the soil in your area; you will find that areas with evergreens tend to have more acidic soils.