\begin{tikzpicture}[every tree node/.style={draw,circle},sibling distance=.25cm]
\Tree
 [.$\forall x$ 
    [.$\lor$
        [.$\imp$
            [.$P$ $x$ $y$ ]
            [.$P$ $x$ $y$ ]
        ]
        [.$\land$
            [.$Q$ $y$ $z$ ]
            [.$\exists y$
                [.$R$ $x$ $y$ $z$ ]
            ] 
        ]
    ]
 ]
\end{tikzpicture}