management in academia I want to explain the particular situation in my university, and advice for how should I act (or at least how my mental status should be).

Traditionally, the management positions in my university (dean of the science school, head of studies, director of PhD program, etc) has been taken by either Full Professors (with a longstanding research record) or Associate Professors with some kind of recognition (an strong research record, mostly).

From a time on, there is an phenomenon that is happening: Full Professors are not willing to take these positions (most of them they have acted already taking such positions) and younger Associate Professors are more interested on research that on management (which is on the other side, something normal, as I think the same :-P). 

My point here is that now all these positions are taken by people (mostly Associate Professors) without research perspective (people with 20 years at university but with 2-3 research papers), and without global perspective. The consequence is that the institutions are decreasing the excellence and the level, and this is something I consider very bad.

I am very active on research and I would like to continue in this way, but I am very worried about this, because I love the institution and I believe that if everybody contributes (just a little!) the things would go better.

Here is my dilemma: as an Associate Professor who loves the institution I am and who wants the best for it I am considering starting doing some management, because I do not like the situation I am seeing. Of course I would prefer to continue focussing on research, which is why I am at the university. My point is that my colleagues (associate professors) that do not care about this issue and continue focussing on research will have an easier path in the forthcoming years to be promoted to full professors (and being clear, a better salary is also something to take care in a decision).

So: which is the mental state I should take: as I want the best for my institution I should sacrifice a little (or a lot) my research time in order to do some management, or should I be more egoist, focus as I am doing, in research with a more chance later to be promoted to Full Professor and take this more apathic point of view?
This is a good question, but I don't see how anyone other than you can answer it. You write that you "[love] the institution ... [and] do not like the situation I am seeing." You also write that "I am very active on research and I would like to continue in this way." You have to ask yourself (i) whether you have the capacity to address both of these things -- some people do, and (ii) if not, which is more important to you. In other words: Would you be happy 5 years from now knowing that you did the best research possible but that you let your environment fall apart? Would you be happy 5 years from now knowing that you tried your best to make your university run well, at the cost of answering the research questions that drive you? Some people would answer 'yes' to the first question; some 'yes' to the second. No one but you can answer this.