# spacing between trees in the forest package

I'm trying to use the forest package to draw adjacent trees. My problem is that the trees are too close to each other.

\documentclass[border=10pt]{standalone}
\usepackage{forest}
\begin{document}
\begin{forest}
for tree={grow=north}
[$a+b\cdot c$
[$\oplus$
[$b\cdot c$
]
[$a$
]
]
]
\end{forest}
\begin{forest}
for tree={grow=north}
[$a+b\cdot c$
[$\oplus$
[$\otimes$
[$c$]
[$b$]
]
[$a$
]
]
]
\end{forest}
\end{document}


On the other hand the following code doesn't generate two adjacent trees, but only the node a.

\documentclass[border=10pt]{standalone}
\usepackage{forest}
\begin{document}
\begin{forest}
for tree={grow=north}
[a
]
[b
]
\end{forest}
\end{document}


How can I draw adjacent trees?

• try to insert \hfil or \hfill between forest trees: \end{forest}\hfil\begin{forest} – Zarko Mar 21 '17 at 18:36
• @Zarko works like a charm! – Arrow Mar 21 '17 at 18:47
• then we can consider question solved by comment? – Zarko Mar 21 '17 at 19:02
• @Zarko I would like to wait a few hours - perhaps someone will show me how to create such diagrams with forest. Is that okay? – Arrow Mar 21 '17 at 19:06
• OK, i will not take any action. About forest diagram, this is not clear what you expect. To have all trees on one image? – Zarko Mar 21 '17 at 19:09

Only one tree is permitted in any forest, whose name is hopelessly misleading. You can have many trees with Forest, but only one in each forest. That is, a forest of trees requires many forests.

If you really want multiple trees in a forest, you can wrap them in a tree shell with a phantom root.

\documentclass[border=10pt]{standalone}
\usepackage{forest}
\begin{document}
\begin{forest}
for tree={grow=north}
[, phantom, fit=band
[$a+b\cdot c$
[$\oplus$
[$b\cdot c$
]
[$a$
]
]
]
[$a+b\cdot c$
[$\oplus$
[$\otimes$
[$c$]
[$b$]
]
[$a$
]
]
]
]
\end{forest}
\end{document}


I don't know why you would bother, though.