We are all part of ecosystems whose behaviour has great impacts on our lives. Yet, understanding and predicting the behaviour of ecosystems is still an open challenge. For more than a century, physicists (and mathematicians) have tried to give their contribution. An ecosystem is a large collection of different interacting species displaying a complex behaviour and therefore, from my perspective as someone pretending to be a stastical physicist, it is natural to try to develop a simplified model that can help us better understanding this behaviour. But does all this make sense? I have not understood it yet but I have many doubts to share. In my talk, after briefly introducing a few physical models of ecosystems, I will focus on the generalized Lotka-Volterra model trying to discuss some of its potentials, shortcoming and doubts.