As for at the moment, lower ranks have no karma requirements to rank up. There probably will be requirements not to have negative karma (I'm not sure that at the moment), but even with 0 karma they can rank up to Senior. 
Ugh, I'm so forgetful! I can't believe I forgot, even though I have said this to many members but still while writing that post It didn't come to my mind, actually, I am spending time on two forums, which have different rules so that's why I got confused maybe. Next time I will keep it in mind. Although I am wrong about my statement directly but indirectly it helps them.
This means, if we will give karma to newbies then they will be motivated, and thus more contributions will be seen on the forum as well. Although there are great measures to tag some shitposter with various tags. But still, thanks for reminding this one, as I was totally off.
More informaition: Karma 0 = your rank will go up.
Thanks to you too for reminding me, as I said to jokers that I already knew about this fact but only forgot while writing that post. So, are you suggesting admin is working to bring some ranking system in which Karma will be counted as well?