I have the following tree and want to increase the vertical space between the nodes. Is there a straightforward way to do this?
\documentclass{article}
\usepackage{forest}
\forestset{
sn edges/.style={for tree={parent anchor=south, child anchor=north,align=center,base=bottom,where n children=0{tier=word}{}}},
background tree/.style={for tree={text opacity=0.2,draw opacity=0.2,edge={draw opacity=0.2}}}
}
\begin{document}
\begin{forest}
sn edges
[D-Struktur,edge label={node[midway,right]{move $\alpha$}}
[S-Struktur
[Tilgungsregeln{,}\\Filter{,} phonol. Regeln
[Phonetische\\Form (PF)]]
[Regeln des anaphorischen Bezugs{,}\\der Quantifizierung und der Kontrolle
[Logische\\Form (LF)]]]]
\end{forest}
\end{document}