"a strong case against the idea that those plants use their deep roots to find moisture during times of scarcity. In fact, they might not be using them to draw moisture at all...prairie has survived droughts, grazing, and fire. The root system beneath these plants plays a major role in that resilience, but not in the way many of us have been taught...Despite having very deep roots, most prairie grasses pull water primarily from the top 10 inches or so of the soil...found that shrubs pull water from much deeper in the soil than grasses and forbs, starting at about 18 inches and reaching down to 8 or 10 feet...species such as sumac and dogwood, but not to more forb-like shrubs such as leadplant or New Jersey tea...Fortunately, while shrubs seem to have some serious advantages belowground, they still have a major disadvantage above ground, which is that their growing points are up in the air. Grasses produce new tillers (aboveground stems) from buds at or below the ground surface. That means that when they are grazed or burned off, they only lose the aboveground plant material they've invested in during the current growing season. If that defoliation occurs during the dormant season, it really doesn't bother them at all because all their living biomass is safely belowground. Shrubs, however, put on new growth from the tips of their aboveground stems. When fire comes through and destroys all their aboveground tissue, they lose a considerable investment, even during the dormant season, and have to start rebuilding from the ground..."
https://prairieecologist.com/2019/09/17/a-deep-rooted-prairie-myth/
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