title: Disentangling above- and below-ground facilitation drivers in arid environments: the role of soil microorganisms, soil properties and microhabitat.
abstract: Nurse plants promote establishment of other plant species by buffering climate extremes and improving soil properties. Soil biota plays an important role, but an analysis to disentangle the effects of soil microorganisms, soil properties and microclimate on facilitation is lacking. In three microhabitats (gaps, small and large Retama shrubs), we placed six microcosms with sterilized soil, two per soil origin (i.e. from each microhabitat). One in every pair received an alive, and the other a sterile, inoculum from its own soil. Seeds of annual plants were sown into the microcosms. Germination, survival and biomass were monitored. Soil bacterial communities were characterized by pyrosequencing. Germination in living Retama inoculum was nearly double that of germination in sterile inoculum. Germination was greater under Retama canopies than in gaps. Biomass was up to three times higher in nurse than in gap soils. Soil microorganisms, soil properties and microclimate showed a range of positive to negative effects on understory plants depending on species identity and life stage. Nurse soil microorganisms promoted germination, but the effect was smaller than the positive effects of soil properties and microclimate under nurses. Nurse below-ground environment (soil properties and microorganisms) promoted plant growth and survival more than nurse microhabitat.
authors.affiliation: Estación Experimental de Zonas Áridas, Spanish National Research Council (EEZA-CSIC), Carretera de Sacramento s/n, E-04120, La Cañada de San Urbano, Almería, Spain.
authors.forename: Yudi M
authors.initials: YM
authors.lastname: Lozano
authors.affiliation: Estación Experimental de Zonas Áridas, Spanish National Research Council (EEZA-CSIC), Carretera de Sacramento s/n, E-04120, La Cañada de San Urbano, Almería, Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Armas
authors.affiliation: Western Sydney University, Hawkesbury Institute for the Environment, Locked Bag 1797, Penrith, NSW, 2751, Australia.
authors.forename: Sara
authors.initials: S
authors.lastname: Hortal
authors.affiliation: Unidad de Bioestadística del Centro Agronómico Tropical de Investigación y Enseñanza (CATIE), Turrialba, 7170, Costa Rica.
authors.forename: Fernando
authors.initials: F
authors.lastname: Casanoves
authors.affiliation: Estación Experimental de Zonas Áridas, Spanish National Research Council (EEZA-CSIC), Carretera de Sacramento s/n, E-04120, La Cañada de San Urbano, Almería, Spain.
authors.forename: Francisco I
authors.initials: FI
authors.lastname: Pugnaire
mesh_terms: D017753:Ecosystem; D007887:Fabaceae / Q000502:physiology*; D018525:Germination; D008834:Microclimate; D063245:Plant Development; D012987:Soil / Q000737:chemistry; D012988:Soil Microbiology; D013030:Spain
chemical_list: D012987:Soil
keywords: 454 pyrosequencing; microhabitat conditions; plant-plant interactions; plant-soil interactions; seed germination; soil bacterial communities; soil nutrients