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What Causes Oak Trees to Die? |
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The following is taken from Ron Smith, Horticulturist, NDSU Extension Service
Q: What causes oaks to die when several feet of soil are packed around the roots and air is pushed out? (E-mail reference)
A: Thats a good question. Oaks are especially sensitive to soil fill over their roots, with just inches, not feet of fill resulting in their death. When the air is driven out of the root zone, anaerobic conditions then exist and the free exchange of respiration gasses cant be released. The roots cannot pick up enough oxygen from the soil pores. In the absence of this oxygen, the meristematic regions of the small roots are injured because of inadequate aeration. When this occurs, alcohol, lactic acid and other incompletely oxidized substances accumulate in the roots, resulting in their eventual death. Basically, in the absence of oxygen, the terminal electron transport system cannot operate, which then results in less energy being produced, growth being reduced and finally death due to the accumulation of toxic substances. Its like the Great Salt Lake in Utah; everything accumulates, nothing flows out. The result is something that cannot support life as we know it (great for floating things though). In nature, distribution of many species is restricted by high oxygen requirements, which exclude them from flood plains or areas where soil tends to be saturated. Those that are adapted to flooding and can tolerate backfilling to a certain degree have a stem or root system that interacts in some way to affect the gas exchange, or they are simply tolerant of anaerobic respiration.
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Last Updated on Sunday, 19 October 2008 10:18 |