Readily Available Water in Forest Soils1
- R. N. Gaiser2
Year-long records of soil moisture are reported for three forest soils of southeastern Ohio. Sustained maximum and minimum soil moisture levels are in close agreement with the moisture equivalent and permanent-wilting percentage as determined in the laboratory and greenhouse. Data on the relationship of readily available water to soil texture are presented for soils of the Muskingum-Wellston-Zanesville association.
Moisture losses from the soil through transpiration and evaporation during the 1951 growing season amounted to 13, 12, and 23 inches for the soils examined. The greatest loss was from Zaleski loam on a lower slope, and the smaller losses were from Wellston silt loam and Muskingum loam found on a ridge and upper slope. It is believed that moisture losses through evaporation from the soil proper are small and that the losses reported closely approximate the amount of moisture extracted for transpiration. The growth rate of white oak (Quercus alba L.) is considerably more rapid on the Zaleski loam than on the other soils.
Because utilization of water is complete on the moist sites, it appears that the oak forests are capable of transpiring more water than is ordinarily available. In years of average precipitation, as much as 25 inches of water might be used in transpiration from trees and evaporation from all soil surfaces in the forest during the growing season. The remaining 15 inches of the average 40-inch rainfall may be accounted for by evaporation, runoff, and deep seepage during the rest of the year.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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