Trees are NOT a requirement to slackline. It's possible to set up a slackline almost anywhere. Take a closer look at the free-standing solutions.
Winbold, Slackline Kit Slack Line Longer 57 Ft Line Uganda
How to Set Up A Slackline with No Trees (Just Lawn) - Quitting Sitting
Gibbon Slacklines Independence Kit – Slacklining without Trees – Slackline Shop Australia
How to Set Up A Slackline with No Trees (Just Lawn) - Quitting Sitting
How to setup a slackline without trees, Learn about all the most common ways to setup a slackline without trees. — Balance Training Forum
Gibbon Classic Line 15m Slackline with Treewear Set Tight Rope 2020
Gibbon Slacklines Independence Kit Classic, Slacklining without trees, with 2 slackframes, 2 x 70cm ground screws and the famous Classic Line 15 m, setup heights: 30/50/70 cm : : Sports & Outdoors
Learn – Slackline Industries USA
Learn – Slackline Industries USA
Learn – Slackline Industries USA
Slackline Course in Tantra Park
Buy Zero Gravity Slacklines Slackline Kit with Industry Leading Carry/Storage Bag, Upgraded Ratchet w/Molded Finger Grip & Smooth Operation + Tree Protectors; Great Set for Kids, in All respects Online at desertcartParaguay
Gibbon Slacklines Independence Kit – Slacklining without Trees – Slackline Shop Australia
The 5 Best Slacklines
Buy EG Exposed Gear Slackline Kit with Tree Protectors, High Grade Ratchet + Cover, Set Up Instruction Booklet and Carry Bag, Classic 60 ft Slack Line Set