TY - JOUR
T1 - Impact of Hydraulic Redistribution on Multispecies Vegetation Water Use in a Semiarid Savanna Ecosystem
T2 - An Experimental and Modeling Synthesis
AU - Lee, Esther
AU - Kumar, Praveen
AU - Barron-Gafford, Greg A.
AU - Hendryx, Sean M.
AU - Sanchez-Cañete, Enrique P.
AU - Minor, Rebecca L.
AU - Colella, Tony
AU - Scott, Russell L.
N1 - Publisher Copyright:
© 2018. American Geophysical Union. All Rights Reserved.
PY - 2018/6
Y1 - 2018/6
N2 - A major challenge in critical zone science is to understand and predict the interaction between above-ground and below-ground ecohydrologic processes. One process that facilitates this connection is hydraulic redistribution, a phenomenon by which roots serve as preferential pathways for water movement from wet to dry soil layers. We use a multilayer canopy model in conjunction with experimental data to quantify the influence of hydraulic redistribution on ecohydrologic processes in order to characterize the competitive and facilitative interaction between mesquite trees and bunchgrasses in a semiarid savanna. Both measured and simulated results show that hydraulic descent dominates during the wet monsoon season, whereas hydraulic lift occurs between precipitation events. For 2015 year-long simulation, we find about 17% of precipitation is absorbed as soil moisture, with the rest of the precipitation returning to the atmosphere as evapotranspiration. In the wet season, 13% of precipitation is transferred to deep soil (>1.5 m) through roots, and in the dry season, 9% of this redistributed water is then transported back to shallow soil depths (<0.5 m). Assuming water supplied through hydraulic redistribution is well-mixed with moisture transported directly through the soil matrix and supports vegetation evapotranspiration, hydraulic redistribution supports 47% of mesquite transpiration and 9% of understory transpiration. Through modeling and experimental synthesis, this study demonstrates that in semiarid savanna ecosystems, mesquite exhibits a competitive advantage over understory bunchgrass through hydraulic redistribution. This analysis evaluates the relationship between two coexisting vegetation types that could be expanded to multiple vegetation species sharing resources in an ecosystem.
AB - A major challenge in critical zone science is to understand and predict the interaction between above-ground and below-ground ecohydrologic processes. One process that facilitates this connection is hydraulic redistribution, a phenomenon by which roots serve as preferential pathways for water movement from wet to dry soil layers. We use a multilayer canopy model in conjunction with experimental data to quantify the influence of hydraulic redistribution on ecohydrologic processes in order to characterize the competitive and facilitative interaction between mesquite trees and bunchgrasses in a semiarid savanna. Both measured and simulated results show that hydraulic descent dominates during the wet monsoon season, whereas hydraulic lift occurs between precipitation events. For 2015 year-long simulation, we find about 17% of precipitation is absorbed as soil moisture, with the rest of the precipitation returning to the atmosphere as evapotranspiration. In the wet season, 13% of precipitation is transferred to deep soil (>1.5 m) through roots, and in the dry season, 9% of this redistributed water is then transported back to shallow soil depths (<0.5 m). Assuming water supplied through hydraulic redistribution is well-mixed with moisture transported directly through the soil matrix and supports vegetation evapotranspiration, hydraulic redistribution supports 47% of mesquite transpiration and 9% of understory transpiration. Through modeling and experimental synthesis, this study demonstrates that in semiarid savanna ecosystems, mesquite exhibits a competitive advantage over understory bunchgrass through hydraulic redistribution. This analysis evaluates the relationship between two coexisting vegetation types that could be expanded to multiple vegetation species sharing resources in an ecosystem.
KW - hydraulic redistribution
KW - semiarid
KW - water use
UR - http://www.scopus.com/inward/record.url?scp=85050807248&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85050807248&partnerID=8YFLogxK
U2 - 10.1029/2017WR021006
DO - 10.1029/2017WR021006
M3 - Article
AN - SCOPUS:85050807248
SN - 0043-1397
VL - 54
SP - 4009
EP - 4027
JO - Water Resources Research
JF - Water Resources Research
IS - 6
ER -