[culi]

Avocado trees on plantations are usually specifically pruned not to grow past 2-3 meters to make them easy to pick. In the wild they can grow 5x this size, but the article is specifically talking about a plantation

[mkl]

If you look at the pictures of the site [1] you'll see there's essentially no shade from these stones for trees, even 2-3 metre ones.

[1] https://tp.revistas.csic.es/index.php/tp/article/view/881/95...