Answer and Explanation:
In romanticism, nature was used to show the state of mind of the speaker, being an environment full of subjectivity and full of meanings. In these works, nature is constantly shown as a source of escapism, where the speaker manages to escape its reality and deposit its deepest thoughts.
In naturalism, nature is considered to be the forming factor of human character. For the authors of naturalism, human beings are the fruits of nature and the environment in which they live, it is essential for the construction of personality. In this regard, nature loses a little of its subjective character and shows itself a little more realistically, but it is presented as something alive and highly influential.
In realism, nature is represented as it really is, losing all the subjectivism of romanticism and the ability to influence naturalism, being represented only as a scenario.