Please bear with me as I'm new to the forum and sketchy on my posting ability. I'm interesting in learning more about the mast years of white spruce. How often do they naturally occur and what factors play a part in their frequency? Both my neighbour and I have mature trees but we have different mast years. I had one in 2002 and she is having one this year. I'm in Calgary. Thanks and I hope I can find this again.