Titus regrets the supposed control he assumed while on the hunt, believing the forest to be a space which harbors the worst humanity has to offer. 

Marcus referring to nature as a “den” is an attempt to distance himself from the violence occuring there, it being a place for animals rather than humans to exist. He believes the ‘natural’ setting of the woods exists separately from the civilized world of humans, which possess higher morals and do not engage in such acts.
Still, this condemnation of nature seems somewhat ironic given the play’s city setting. In the case of Rome, conquering has become codified into its culture and law. The play opens with a celebration of violence, beginning with a near military crisis over leadership and continuing with vengeful sacrifices of Goths. The play’s crowning ultraviolence occurs in the woods, yet the levels of violence accepted within the society cannot be ignored either -- death occurs plentifully within the city’s walls. Lavinia’s death occurs not in the forest, but in a ‘civilized’ space, while having dinner. There is irony in the characters only transparently seeing violence in the woods, for it is only here (the forest) these formally powerful characters too are truncated from their agency giving power structure of Roman law. The bloodshed within the city walls is merely justified violence, logical because the laws permits it.
Given Shakespeare’s previous metaphorical use of trees in singular instances, and the aforementioned characters rebuking of nature as a whole, trees stationary in a forest represent the harm people suffer at the hand of a larger structure. The structure can be a system of laws, a lack of them, a more powerful empire, or primal instincts which cause unacceptable actions. Trees stuck in a forest are comparable to humans stuck in a larger structure beyond their control.
Titus’ explication of agency using the tree metaphor for human bodies demonstrates the vulnerability actors in society who lack proper power, and the potential for violence in every system. For Rome, these corruptions are egregiously obvious, while Shakespeare’s contemporary Britain may have thought the problems expressed in Titus were exclusive to archaic societies, or merely a cautionary tale. Through deconstruction, Shakespeare instructs the reader to compare contemporary practices to Roman ultraviolence, and identify which ‘characters’ may be similar to the trees depicted in Titus.
