Yes it’s definitely exercise. I use a calorie counting app and you can record your exercise to add extra calories to your daily allowance. I log 30 mins animal care daily which gives me 119 calories. 1 hour general riding gives me 306 calories.
It’s a yes from me. However, no personal trainer would recommend that someone went and did yard work to get fit. Little do they know what an all round work out it can be.