How do I know the angle of the hollow?
The angle of the hollow can sometimes be important for factors such as water drainage. We are interested in knowing if the hollow that you are monitoring is vertical, horizontal, or somewhere in between. If the hollow occurs in the main trunk, or a branch that is straight up or down, this will be a vertical hollow. If it’s sticking out at a right angle from the trunk, it’s horizontal. If it’s sticking out at an angle halfway between vertical and horizontal, this is 45 degrees. Record whether the angle is ‘vertical’, ‘between vertical and 45 degrees’, ‘between 45 degrees and horizontal’ or ‘horizontal’. If it’s greater than horizontal and angled downwards, record this as ‘downwards’.