To Zilore -
You find no traps.
To Dorgath -
You cautiously move the plank to the side and poke your head out.
You see that the ladder leads up into a thin, rockey ravine. There is a sloped path leading in both directions, and trees up on the banks, which are at least 15 feet high (the banks, that is). You see no guards, or indeed, no signs of life at all.
You also see that the plank you moved has been cleverly carved and painted to look like the rockey ground it sits on.