32 bit programs, such as Bryce, can only use 2GB of RAM, there is a cheat available if your software is Large Address Aware, Bryce is not, nor can it be made to be without a major rewrite of the software.

Now comes the fun part, when you open DAZ Studio from within Bryce, they both are limited to the SAME 2GB of RAM that Bryce is using, so even having a 64 bit computer, with 128GB of RAM will not help you in this case.  

So what you are, most likely, running into is a memory limitation of 32 bit software, trying to do to much. 

As a suggestion, if you wish to use Bryce, render your Bryce scene as a background. Get a copy of PW Catch, and follow the directions of how to set up the scene in DS. PW Catch will, in most cases, allow you to take a render, or Photo and use it as a background, and a ground plane, with a shadow and reflection catcher, and a foreground scene in which to place the rest of your scene within DAZ Studio. It does this using significantly less RAM than trying render the combined scene. (Going eiher from DS to Bryce or especially trying to go from Bryce to DS using the bridge.)