use ajaxKeys of the tree.
ah.. b.t.w. sorry I slightly misunderstand your case.
Yes, all the form is submitted. AjaxSingle and region limits only processing of the components. And this can't be configured to works in different way.
State saving set to server could slightly improve this because state information will not be passed and received with every request.
thanks for answer
i will try to put tree outside of form and after commandlink click fire form's js submit with parameters.
i think this little trick will work.