If you are in a full-time LTO assignment, you are expected to attend staff meetings.

If you are in a part-time LTO assignment, you only have to attend staff meetings if they fall immediately before or after your teaching time.  If staff meetings are Wednesday afternoon but you only teach mornings, or you only teach Tuesdays, you are not expected to attend.  You may choose to attend (e.g., if you are organizing a school event and need to provide details), but you are not required to be there.  You should, however, be sure to catch up on anything missed.