Can forums bring down your search engine rankings?

[prospects]

it might be my imagination, but i could swear that after the launch of a bbpress forum and posts and replies coming from members, the site alexa website rankings actually went DOWN for a while.

i always thought forums would de facto bring up rankings - more content, traffic, etc.  Is it possible that forum content is considered lower quality?  i remember reading that lots of new threads and such from forum members can actually hurt your rankings- is this true?

i guess i'm trying to figure out: on balance, what is the impact of forums on rankings - and if there are any negative impacts, if you still want to have one, how to minimize the downside?

thanks much for any help!

[EGOL]

First, I would not bet anything on Alexa data.  It is based upon a toolbar that very few people use.

If you are interested in what a forum does to your search engine rankings then start tracking your Google rankings with the SEOmoz rank tracking tool.

Now, can a forum damage your rankings?  I can imagine two situations where it might.

1. lots of trivial content, duplicate content or trash content is posted in your forum

2. forum members flood your threads with links out to spammy sites, manipulative sites, or sites about topics that google does not like