Maintenance of Root Function in Tropical Woody Species During Droughts: Hydraulic Redistribution, Refilling of Embolized Vessels, and Facilitation Between Plants

F.G. SCHOLZ, S.J. BUCCI, F.C. MEINZER AND G. GOLDSTEIN

Tropical Tree Physiology Adaptations and Responses in a Changing Environment

SPRINGER-VERLAG

Año: 2016; p. 227 - 241

Most woody dominated tropical ecosystems are subjected to droughtperiods of different lengths, from few days or weeks in wet forests to severalmonths in drought deciduous forests and savanna ecosystems. The roots duringthese low soil water availability periods may experience hydraulic and metabolicdysfunctions resulting not only in a substantial decrease in root growth rates, butalso in reduced water and nutrient uptake activity. We discuss three groups ofprocesses: (1) hydraulic redistribution, (2) refilling of embolized vessels, and(3) ecological facilitation, which can contribute together or in isolation to continuousroot activities despite low soil water availability. Furthermore they can helpavoid physiological uncoupling between above and belowground plant parts andthus help to preserve the integration of the root, stem and leaf hydraulic continuumwithin trees. The two mechanisms for refilling embolized vessels that help repairthe functionality of the water transport system discussed are the transient pressureimbalance between the xylem and surrounding tissues, and positive root pressures.