Ive heard that the calf burning isn't just from using the calves, but also from your flexibility and range of motion. So strength training for the calves is good...jumping rope probably is great, but in addition make sure to stretch regularly to increase your calf range of motion to make the most use out of your muscles during snowboarding.

Those and squats for the thighs, or wall sits...Ive been doing both to prepare for boarding season, but we have gotten SQUAT for good snow in years. /sigh