Why does the action of the play begin in the nursery?what is beginning? What is ending?

The Cherry Orchard focuses on the tensions of changing times. For example, the room in Act I is called a nursery, although it has held no baby for years, and this misnomer introduces a nostalgic atmosphere into Madame Ranevsky's house. This tension between what was and what is centers on different levels. One level, personal tragedy, is very specific, and the death of Madame Ranevsky's son Grisha five years before the start of the play is one example. On another level, the play centers on the complications with major changes in an entire society: the recent freedom of the serfs and the decaying power of the aristocracy are two more general aspects of Russian history which affect the play. You can check out endings and beginnings ate the link below:

http://www.gradesaver.com/the-cherry-orchard/study-guide/summary-act-i