The road was partially blocked by a fallen tree.

倒下的一棵树挡住了部分道路。

《牛津词典》

I came across a fallen tree.

我经过一棵伐倒的树。

youdao

He went into the jungle, searching until he found a fallen tree of a certain species of hardwood.

他走到丛林中，直到发现了一棵倒下的一种阔叶树才停止了他的搜寻。

youdao

If you ever tried to walk on a fallen tree log, you understand what the expression means.

VOA: special.2009.06.07

"It gives drivers sufficient time to react if there is, for example, a fallen tree on the line, " she said.

BBC: NEWS | UK | England | Power supplies cut by high winds

Rachel McDonald, the pub's owner, said there was "lots of mud everywhere" and said the river had been blocked by a fallen tree trunk.

BBC: Homes in Somerset are flooded as river bursts

One used mushrooms on mossy bark harvested from a fallen tree.

WSJ: Greenery, With Hints of the Forest and Desert