Biology of Dryland Plants
Schenk, H. Jochen .
Dryland root ecology.
In most arid ecosystems, water availability is the main growth-limiting factor for plants. Dryland plants therefore need root systems sufficiently deep and wide to enable them to take up enough water for their survival, growth, and reproduction. But infiltration depths in arid environments are highly variable temporally and seasonally, leaving plants with "choices" to either rely on water in shallow (1.2 m) soil layers, or on groundwater. Due to the high long-term variability of precipitation in arid climates, shallow water infiltration is most common and therefore the most reliable, but most short-lived source of water, medium infiltration is more rare, and deep infiltration most rare, most long-lived, but least reliable. Plants in arid lands tap in either one or all of these pools, depending on the shape of their root systems, their phenologies, and their growth-forms. A global database of root systems shapes and sizes collected from the literature was used to quantify sizes and shapes of root systems in arid ecosystems for a variety of plants growth forms in order to determine which pools of water are typically utilized by these growth forms, and to analyze relationships between root systems, plant phenologies, and the variable and seasonal nature of infiltration into the soil. Dryland plant species that show hydraulic segmentation at the whole-plant level are discussed as a special case study. Individual roots in such species are hydraulically connected to only a part of the shoot system, providing the plants with a high degree of hydraulic redundancy, reducing wasteful water loss, and increasing chances of survival.
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1 - California State University Fullerton, Department of Biological Science, PO Box 6850, Fullerton, California, 92834-6850, USA
plant growth forms.
Presentation Type: Symposium or Colloquium Presentation
Location: Salon K - Austin Grand Ballroom/Hilton
Date: Wednesday, August 17th, 2005
Time: 10:15 AM