A control arrangement (20) comprises at least one sensor (7). The sensor (7) is adapted to detect at least one object (9) in an area of at least one predefined sector (10) focused in an area between a control cabin (5) and a boom end (11), and to detect at least one of the following: location information of said detected object at two different time instants, at least, and the speed of said detected object The control arrangement (20) additionally comprises at least one control unit (8) adapted to determine at least the direction of travel of said detected object (9) in relation to the control cabin at two different time instants, at least, on the basis of the detected location information and/or the detected speed of the object (9), and cause a change in the control of a forest machine in response to the detected direction of movement of the detected object (9) being directed towards the control cabin in the area of the sector (10).
