Ask Mr. Smarty Plants

Your questions, while interesting, are too general to be plainly answered.  Native plant species are always well-adapted to the ecological niche in which they naturally evolved and grow.  Valdosta, being a medium-sized city, has many, many ecological niches -  both natural and man-made - which may or may not be well-suited for one native plant species or for a specific invasive species.  

Perhaps an example will help.  You are likely to find healthy populations of the native species, Cyperus retrorsus in the pine woodlands around Valdosta, but are very unlikely to find it on disturbed sites along roadways, streets and in residential gardens in the area.  On the other hand, the invasive weed, Cyperus rotundus is likely to appear in any disturbed soils locally, but is very unlikely to appear in well-established pine forests and will not compete well with C. retrorsus if it does.

How any plant reacts to carbon dioxide levels, hypertonic or otherwise, depends on many factors, but strictly speaking, the species' nativity is not among those factors.  Soil constituents and conditions, water and nutrient availability, sun conditions, neighboring and competing plants, plant health and the individual plant species' genetics will all play a role in that plant's reaction to the levels of CO2 and other atmospheric gas fractions.

You will probably want to give more thought to the design of your experiment before proceeding.