title: Geoecohydrological mechanisms couple soil and leaf water dynamics and facilitate species coexistence in shallow soils of a tropical semiarid mixed forest.
abstract: Trees growing on shallow rocky soils must have exceptional adaptations when underlying weathered bedrock has no deep fractures for water storage. Under semiarid conditions, hydrology of shallow soils is expected to decouple from plant hydrology, as soils dry out as a result of rapid evaporation and competition for water increases between coexisting tree species. Gas exchange and plant-water relations were monitored for 15 months for Pinus cembroides and Quercus potosina tree species in a tropical semiarid forest growing on c. 20-cm-deep soils over impermeable volcanic bedrock. Soil and leaf water potential maintained a relatively constant offset throughout the year in spite of high intra-annual fluctuations reaching up to 5 MPa. Thus, hydrology of shallow soils did not decouple from hydrology of trees even in the driest period. A combination of redistribution mechanisms of water stored in weathered bedrock and hypodermic flow accessible to oak provided the source of water supply to shallow soils, where most of the actively growing roots occurred. This study demonstrates a unique geoecohydrological mechanism that maintains a tightly coupled hydrology between shallow rocky soils and trees, as well as species coexistence in this mixed forest, where oak facilitates water access to pine.
authors.affiliation: División de Ciencias Ambientales, Instituto Potosino de Investigación Científica y Tecnológica, Camino a la Presa de San José No. 2055 Lomas 4ta, C.P. 78216, San Luís Potosí, México.
authors.forename: Ulises
authors.initials: U
authors.lastname: Rodríguez-Robles
authors.affiliation: División de Ciencias Ambientales, Instituto Potosino de Investigación Científica y Tecnológica, Camino a la Presa de San José No. 2055 Lomas 4ta, C.P. 78216, San Luís Potosí, México.
authors.forename: J Tulio
authors.initials: JT
authors.lastname: Arredondo
authors.affiliation: División de Ciencias Ambientales, Instituto Potosino de Investigación Científica y Tecnológica, Camino a la Presa de San José No. 2055 Lomas 4ta, C.P. 78216, San Luís Potosí, México.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Huber-Sannwald
authors.affiliation: Department of Plant & Soil Sciences, University of Delaware, Newark, DE, 19716, USA.
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Vargas
mesh_terms: D065928:Forests; D005740:Gases / Q000378:metabolism; D005843:Geography; D062070:Hydrology; D008800:Mexico; D028223:Pinus / Q000502:physiology; D018515:Plant Leaves / Q000502:physiology*; D054046:Plant Stomata / Q000502:physiology; D029963:Quercus / Q000502:physiology; D011891:Rain; D012621:Seasons; D012987:Soil / Q000737:chemistry*; D013045:Species Specificity; D014197:Trees / Q000502:physiology; D014329:Tropical Climate; D014867:Water / Q000502:physiology*
chemical_list: D005740:Gases; D012987:Soil; D014867:Water
keywords: Pinus cembroides; Quercus potosina; geoecohydrological mechanisms; plant coexistence; shallow soils; tropical semiarid forest; water redistribution mechanisms; weathered rocks