Emily Dickinson's work is certainly famous for a number of different reasons. Key themes that abound in her work and have been amply documented are death, love and marriage and the way that her poems try to define experiences and objects that otherwise escape definition. However, I am going to respond to your question by talking about the theme of Nature. I have previously responded to other questions about the theme of death in Dickinson's work, and if you search in this group you will probably find a number of different responses, including mine.
A number of the poems of Emily Dickinson centre on the relationship between the natural world and the human. What is interesting about Dickinson's presentation of nature, however, is the way that she presents it as a projection of an internal drama or as an antagonist that has real body and shape. Whilst Dickinson did have a real respect for and love of nature, which is made clear in such poems as "How the Mountains drip with Sunset," it is hard to ignore that more often nature is presented as being indifferent or threatening. Consider how the indifference of nature is presented in "Apparently with no surprise" and how nature is viewed as incredibly threatening and disturbing in "A narrow Fellow in the Grass." Also note how, contrary to Romantic poets, nature, for Dickinson, does not heal or bring comfort to the soul. In "I dreaded that first Robin, so," nature does not alleviate the internal pain of the speaker. It only makes it more acute by its indifference to her suffering.
Therefore, when considering the theme of nature in Dickinson's work, it is important to look beyond the Romantic sensibilities of authors such as Wordsworth and see how nature assumes an altogether more sinister and indifferent shape.