We had a black belt test in Toronto today.
I spent quite some time looking for suitable woods for wood cutting test. I found that cedar is the best candidate. It's soft enough that you can break without too much problem yet requires certain amount of power and speed to break. Much better than treated pine.

Are the dimensions the same for cedar sticks - 1 inch by 1 inch and 2 feet long?

The U.S. headquarters began offering a different alternative several months ago. The sticks they're supplying are cut from particle board. Sheets of particle board are only 3/4 inches thick, so the sticks are 3/4" x 1". However, I've found that sticks of that material are noticeably easier to break compared to those used in Korea. A way around that is to simply cut the sticks wider, say 3/4" x 1 1/2". Better yet, offer the sticks in a variety of widths to provide degrees of difficulty.