On a tip from a friend I skied in about 5 km on snowmobile trails in central Ontario (east of Bancroft on Hwy 28) - coordinates and map link on http://www.ancientforest.org/forest-info/?Num=133
. I was mostly skiing through pretty young forest with a lot of aspen, but my friend had cored a white cedar in there at >250 years old. The whole area is unprotected crown land.
When I got in there I realized that most of the old forest was swamp forest adjacent to Snake Creek - the trees are smallish for their age, but appeared to be mostly around 150-200-year-old cedars, with the occasional tamarack. I couldn't resist coring one of the tamaracks - I missed the center by maybe 5 years, but still counted 161 rings, putting it at about 180 years (using a probably conservative 15 years for breast height). It was 37 cm diameter and 20.1 m tall.
Found a nice but small upland grove just off the trail, with some larger cedars and a few yellow birches, and a basswood showing phenomenal characteristics of age - beauty sinuous trunk.
All in all a nice day. There might be more to see in there, the bush is pretty thick and hard to get around it in winter, but I suspect the upland forest is pretty limited.