Armatocereus laetus roots respond rapidly to small rainfall events
Roots of Armatocereus laetus in a seasonally dry Ecuadorian forest rapidly resumed water uptake following small rainfall events. The paper, published in June 2026, presents 17 months of measurements of this cactus and three co-occurring tree species. Miniature heat-based sensors recorded water flow through roots measuring 2 to 6 mm in diameter. In the cactus, isolated dry-season rainfall events caused rapid increases in flow, whereas tree root activity depended more strongly on leaf presence and soil moisture. During the monitored periods, cactus roots often took up water for almost the entire day and night. Their activity was less closely associated with atmospheric evaporative demand than that of roots of the comparison tree Eriotheca ruizii.
The measurements show how root water uptake complements water storage in a succulent stem in an environment with irregular rainfall. The most complete time series came from one root per species, so the findings describe the responses of the monitored roots.
Würzberg L., Homeier J., Coners H., Mundry R., Gonzaga Poma J.A., Windhorst D., Trachte K., Scholz S., Bendix J., Leuschner C., Contrasting diurnal and seasonal root water uptake patterns among different plant life forms in a neotropical dry forest, Trees, 2026, 40:83, doi: 10.1007/s00468-026-02784-5.
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