My first issue of the day. While trying to debug the other issue I'm having, I created a debug world. When the DT trees loaded into rendering range, it immediately (before I even saw them) CTD. The error was an issue tesselating the Bamboo branches from DT:BoP. I haven't ever found bamboo previously in other modpacks I've had so I can't say for sure when this issue started.

Tesselating Render Crash Log

This was actually in the Dynamic Trees Biomes O'Plenty mod. But I made a fix for it to clamp the radius range of bamboo. Since I wasn't able to reproduce the bug myself it's untested. If the problem persists then file another issue under the right mod along with steps to reproduce the problem.