Before we go into today's topic of flooding effects on the landscape, we need to thank some people and count our blessings. The real heroes in our society are not the free agent athletes making millions, but the people who were out at 2 a.m. helping people in need, whether it was their job to do so or not. They are the ones who deserve our adoration.

A single day's worth of flooding may take many months to repair. Flooding in the man-made landscape mimics flooding in the natural landscape where land covered in water regularly has little vegetation and almost no debris. Most plants do not survive being covered with water or dried out - often flooded areas consist of mud flats that erode easily. Any floatable litter will be washed up to the high water mark; therefore, the same areas don't have mulch-like materials to prevent more erosion from rains.

You will be able to tell how high the water rose in your yard by finding the line on your remaining bark mulch. Probably the only benefit to gravel mulch in flower beds is that it doesn't wash away easily - it will most likely need to be washed because of the silt that is in the floodwaters. If your mulch disappears, it is a good idea to replace it soon to prevent weeds and dried out flower beds. A simple rule of thumb to remember is that if a plant does not normally grow on the edge of a lake or in a swamp, it won't do well being flooded. The longer it is flooded the worse it will do.

Floodwaters do several things to harm plants. Fast-moving water smashes plants and breaks or cracks their stems and branches - they can not straighten up. This is especially true of plants without wooden stems. Annual flowers and vegetable crops may be ruined and need to be replaced. Perennials can be propped up for now and will grow new stems next year. Shrubs and trees may be supported until they can regain their strength.

When the top of a plant is underwater, the plant has a hard time maintaining the proper level of moisture in the leaves and stems. When it eventually dries out, some leaves may die off. The longer it was beneath the water, the worse it will be. Wash off mud and silt that coat the leaves; they hinder the plant's ability to photosynthesize. Slow growers or already weak plants will have a more difficult time recovering.

Water over the root system drowns the plant slowly, and for some big trees the damage may not be apparent for several weeks or even months. The soil must have oxygen in it for most terrestrial plant roots to survive. Some plants that only grow on upland dry hill areas need loose soil with plenty of air in it. Plants as diverse as oaks and junipers are in this category.

Go to any forest preserve and look for the high ground to see the foliage growing there. Some plants develop along stream banks and near lake shores; they can take low levels of oxygen in the soil around their roots. Certain maples are especially good at tolerating periodic flooding.

Because of the way we change the topography of the land and how people plant new trees in improper locations, many plants are put in areas where they can be harmed by flooding. If the water is gone from the surface in only a few days, there should be no harm to most trees and shrubs. A week or two of water over the root area will stress the plant, and it will have to be watched for other signs of problems for the next year or more. Water covering the plant for longer periods will kill non-flood tolerant ones and leave only the hardy. New plants in these low areas should only be flood tolerant.

Many parking lots are designed to hold floodwater for a while. As they release the water to the retention ponds, they may keep the water levels at the ponds artificially high. Trees around the edges of the ponds should be flood tolerant, but floods will weed out the weak ones.

Most lawn grasses do not endure floodwaters for more than a few days without showing some dying out. Often, grasses growing in low areas are not particularly strong to start; they often have fungal disease problems due to high humidity. Many subdivisions have used park spaces and open areas as flood detention areas. These areas are not intended to stay continuously wet, but are supposed to only hold water for several days.

When it comes to a soccer field or ball diamond, the grass was already weak from the wear and tear of summer activities. If played on while the soil is wet, the ground will become compacted. These lawn areas will need a lot of remedial care to return to full strength. For the safety of the participants, a good lawn care program should be implemented before play is resumed.

Play should be restricted while the soil is soggy. These areas will need core aerations in the fall and possibly an overseeding at that time. If possible, mud should be washed off of grass leaves. The normal fertilization and disease control programs should be followed. Lightning in these storms can add a lot of water-soluble nitrogen to the rain - many plants will green up temporarily.

People with water gardens and backyard ponds may have lost some fish and plants as the surrounding water flooded over the pond levels and the inhabitants floated away.

Overall, there will not be a long lasting effect on the landscape from local flooding, if it doesn't last more than a few days and stays as an occasional occurrence. Unfortunately, some areas are being flooded longer and more often because of land upstream that is being changed from rural to urban.

If there is more flooding to come, especially in the next few weeks, then we must watch out for drowned plants. Fungal disease problems on plants growing in low and shady areas can also become an issue. Until then we will just have to wait and see.

E-mail questions to Jeff Rugg, Kendall County unit educator, University of Illinois Extension at jrugg@uiuc.edu.

© Copley News Service

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