This week, when you watch the Masters, you'll notice many trees have grass growing right up to the base of the tree. Others on the course are surrounded in pinestraw. I'm actually asked regularly about this; specifically why do some trees have grass growing up to their base while others are surrounded by some form of mulch? Personally, I love the look of grass right up to the bottom of the tree and would rather see that, than every tree having a ring of mulch or straw around it.
First, it's important to understand nature and tree health. A tree growing in a forest, is a tree living its best life. Every year, deciduous trees shed their leaves, which fall to the ground. These leaves begin to decay and add valuable organic matter and nutrients to the soil, ultimately being absorbed by the root system of the tree. This is how a tree remains healthy. Every year, the process repeats itself without fail. Those leaves that fall also protect and cover the root system. It's as if the tree is taking care of itself!
Now, consider a tree growing on a golf course. There is a saying that once you plant a tree surrounded by grass (yards, golf courses etc), that is the 1st day of its death. Unlike a tree in the forest, once the leaves fall, we blow those leaves into a pile and haul them away. The tree doesn't have the benefit of organic rich soil and the organic fertilizer it supplies for itself. In addition to that, heavy mowing equipment is continually running over its root system, causing soil compaction and a host of other issues. Furthermore, every week or two, an employee has to weed-eat around the tree which can lead to damaging the cambium layer of the tree; the tree's vascular system which transports nutrients from the roots to the top of the tree.
Many golf courses place mulch below the trees for these reasons: it protects the root system, keep mowers and weed-eaters away from the tree and also allow organic material to break down and fertilize the trees.
There are other factors at play as well. The species of tree will often dictate whether or not grass can be grown up to the base of a tree. Maples, for example are very shallow rooted trees. You can see by the photo below, how much of the root system is exposed below the tree. Grass simply can't compete with this. When grass and trees are growing in the same environment, a tree will always out compete grass for water and nutrients. In situations like this, mulch is often placed around a tree to avoid looking at dead grass or bare ground. I mentioned Maples being shallow rooted. White Pines are similar as well. Oak trees on the other hand, seem to be deeper-rooted on the Highlands CC golf course. This is why between #7 and #8, grass and trees coexist together and offer a great look. Because they coexist, doesn't mean it's in the best interest of the tree.
Hopefully this gives you some insight into the topic of grass and trees. Weighing all of these factors, allows Superintendents to make the best decision for each tree.
