Trees and flooding FAQs

Spring flooding is not uncommon in Michigan. Here are some ways to minimize the impacts of flooding on trees.

How long can trees stand being flooded?
In late winter and early spring, many trees can handle a week or two of flooding without long-term problems. However, tree species vary widely in flood-tolerance. In fact, if we think about environmental stresses, trees vary more in flood-tolerance than any other trait. On one extreme, trees that are native to floodplains, such as cottonwoods, can withstand months of inundation. On the other extreme, upland trees such as pine, hickories and most oaks may be damaged after a week or less of flooding.

How does flooding harm trees?
Tree roots need oxygen in order to function. Normally, tree roots get the oxygen they need from air in the pores spaces in soil. When soils are flooded, these air spaces are filled with water and tree roots undergo anaerobic conditions and are unable to get oxygen for respiration. This can lead to several problems including root death, build-up of toxic compounds within the tree, and reduced nutrient uptake.

What are some symptoms I should watch for as trees recover from flooding?
Once floodwaters recede this spring and the weather beings to warm, most trees should quickly begin to break bud and put on their spring flush of growth. Trees that have been flooded may show delayed budbreak, branch die-back, smaller than normal leaves, wilted leaves or chlorotic leaves.

What should I do if I think my tree has been injured by flooding?
As with many environment-related tree problems, “wait and see” is usually the best advice. Trees that are slow to leaf out compared to their neighbors, for example, are often able to catch up by late spring or early summer. Likewise, flooded trees that initially produce chlorotic or stunted leaves will often resume normal growth as spring progresses. If a flooded tree does not resume normal growth by early summer, or you suspect root damage may have affected the structural stability of the tree, you should have the tree assessed by a professional arborist.

What is the best long-term strategy for dealing with flood-prone areas?
As we noted recently in the Michigan State University Extension article “It’s raining, it’s pouring, and it’s a good time for a landscape site assessment,” the best strategies for dealing with flooding are to either eliminate the flooding problem (i.e., diverting water flow or re-grading) or planting trees that can withstand flooding.

Which trees are most tolerant of flooding?
As you would expect, bottomland or flood-plain species are best adapted to withstand flooding. These trees can typically tolerate several weeks of inundation, especially in late winter or early spring.

  • Red maple (Acer rubrum)
  • Silver maple (Acer saccharinum)
  • River birch (Betula nigra)
  • Hackberry (Celtis occidentalis)
  • Sweetgum (Liquidambar styraciflua)
  • Tupelo or black gum(Nyssa sylvatica)
  • Sycamore (Platanus occidentalis)
  • Eastern cottonwood (Populus deltoides)
  • Swamp white oak (Quercus bicolor)
  • Bur oak (Quercus macrocarpa)
  • Black willow (Salix nigra)
  • Baldcypress (Taxodium distichum)
  • Elms (Ulmus spp.)

Which trees are least tolerant of flooding?
Many trees that are adapted to uplands or other dry sites are not well-adapted to flooding. These trees may be damaged by a week or less of inundation.

  • Sugar maple (Acer saccharum)
  • Yellow buckeye (Aesculus flava)
  • Shagbark hickory (Carya ovata)
  • Eastern redbud (Cercis canadensis)
  • Flowering dogwood (Cornus florida)
  • American beech (Fagus grandifolia)
  • Kentucky coffeetree (Gymnocladus dioicus)
  • Eastern red cedar (Juniperus virginiana)
  • Junipers (Juniperus spp.)
  • Black walnut (Juglans nigra)
  • Tulip poplar (Liriodendron tulipifera)
  • Pines (Pinus spp.)
  • Red oak (Quercus rubra)
  • White oak (Quercus alba)
  • Sassafras (Sassafras albidum)
  • American basswood (Tilia americana)

Dr. Cregg’s work is funded in part by MSU’s AgBioResearch.

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