Silver Maple is one of the most notorious
trees for bumpy lawn surface roots
Some of the
tree species that are notorious for producing surface roots are
those that grow quickly. These include: Norway maple (Acer
platanoides); red maple (Acer rubrum); silver maple (Acer
saccharinum); tree-of-heaven (Ailanthus altissima); alder (Alnus
spp.); river birch (Betula nigra); hackberry (Celtis spp.); American
beech (Fagus grandifolia), thornless honeylocust (Gleditsia
triacanthos var. inermis); European larch (Larix decidua); sweetgum
(Liquidambar styraciflua); dawn redwood (Metasequoia
glyptostroboides); mulberry (Morus spp.); Colorado spruce (Picea
pungens); sycamore or London plane tree (Platanus spp.); poplar (Populus
spp.); pin oak (Quercus palustris); black locust (Robinia
pseudoacacia); willow (Salix spp.); elm (Ulmus spp.) bald cypress (Taxodium
distichum); and linden (Tilia spp.). Many of these are trees that
tolerate adverse growing conditions. Their propensity for producing
surface roots aids in their survival in such situations.
Under the right conditions, any species of tree can produce surface
root systems. Environmental factors play an important role in the
growth of surface roots. It is easier for roots to grow close to the
surface when a tree is grown in hard, compacted clay soil or in
areas where the soil is saturated with water frequently. Roots tend
to grow where they find the most favorable conditions: adequate
water, air and nutrients. In poor growing conditions, the most
favorable place is often close to the soil surface. Also, erosion
can expose a tree's lateral roots.
What about covering roots with soil?
Even if you cover them with soil and reseed the area, those roots
will just grow back up to the soil surface as they continue to grow
in diameter. It is not a good practice to place additional soil over
the root system of any tree, because roots need oxygen. If they are
buried too deeply, they literally suffocate, and the tree will
decline and die over time.
Sometimes people ask if it is okay to cut those roots – the short
answer is “no.” Removing those roots can injure and weaken a tree,
making it more susceptible to insect and disease problems. More
importantly, it creates a hazardous situation since those roots
support the tree, making it more likely to come down in a storm or
under a load of snow.
Finally, continually running over those surface roots with a lawn
mower is not a good idea. The mower wounds them, creating an
entrance into the tree for insect problems and/or disease-causing
organisms. Besides, it's hard on the lawn mower and you!
Pachysandra groundcover around
the base of a Pin Oak
solution is to replace the grass with mulch or a ground cover such
as goldenstar (Chrysogonum virginianum), barrenwort (Epimedium),
creeping lily-turf (Liriope spicata), Allegheny spurge (Pachysandra
procumbens), Japanese spurge (Pachysandra terminalis), creeping
myrtle (Vinca minor), or barren strawberry (Waldsteinia ternata).
Groundcover under trees
Tree replacements for Ash trees