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Phenology and Dynamics of Root Growth of Three Cool Semi-Desert Shrubs Under Field Conditions

Osvaldo A. Fernandez and Martyn M. Caldwell
Journal of Ecology
Vol. 63, No. 2 (Jul., 1975), pp. 703-714
DOI: 10.2307/2258746
Stable URL: http://www.jstor.org/stable/2258746
Page Count: 12
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Phenology and Dynamics of Root Growth of Three Cool Semi-Desert Shrubs Under Field Conditions
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Abstract

The timing and extent of root growth and development were studied under field conditions in root observation chambers. These chambers were located near small groups of established perennial shrubs. Each of the shrub species, Atriplex confertifolia, Ceratoides lanata, and Artemisia tridentata occur in nearly monospecific stands. The presence of the observation chambers was shown to cause minimal disruption of the soil environment since soil temperatures and water potentials immediately proximate to the observation window were the same as those in the undisturbed soil profile. The season of root growth activity was initiated a few days before active shoot growth in the spring and extended for several months after the termination of shoot growth and reproductive development. For all three species there was a clear progression of root growth activity from the upper layers of the profile to greater depths through the season. Continued root growth at greater depths in the profile during the driest portion of the year was particularly evident for Atriplex confertifolia and may be a principal factor enabling this species to transpire and maintain positive net assimilation during this period. Although the root systems of all three shrubs maintain root growth activity for several months, this growth is phased in nature and individual apical meristems of lateral roots are usually active for only one to two weeks. The continual, phased root growth is seen as being of great advantage in increasing the efficiency of utilization of the annual soil moisture recharge and in overcoming the limitations imposed by the greatly reduced hydraulic conductivity of dry soils.

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