Gap after table in LaTeX

If Charles's and midtiby's answers don't fix it for you and you must adjust it (because, for instance the margin lady won't pass your dissertation until you do), you can diddle the lengths

• \floatsep
• \textfloatsep
• \intextsep

(and their two column brethren) which adjust the spacing around and between floats. In this case I believe you want \textfloatsep.

But do what Charles and midtiby said first, and consider Bears' advice as well.

Instead of centering the tables with the {center} environment, try to use the \centering macro. I should be something like

\begin{table}
\centering
...
\end{table}

You can always fix vertical spacing by emitting a vskip command, say \vskip{-1em}, in vertical mode, such as before the \section. Bears is right: delay worrying about layout as late as possible. There should be a saying about premature formatting...

The table would look more attractive to me if the caption was at the bottom. The matter of appearance would be as much what is the proportion of space above and below the caption as the total amount of space.