title: Vulnerability to xylem embolism as a major correlate of the environmental distribution of rain forest species on a tropical island.
abstract: Increases in drought-induced tree mortality are being observed in tropical rain forests worldwide and are also likely to affect the geographical distribution of tropical vegetation. However, the mechanisms underlying the drought vulnerability and environmental distribution of tropical species have been little studied. We measured vulnerability to xylem embolism (P50) of 13 woody species endemic to New Caledonia and with different xylem conduit morphologies. We examined the relation between P50, along with other leaf and xylem functional traits, and a range of habitat variables. Selected species had P50values ranging between -4.03 and -2.00 MPa with most species falling in a narrow range of resistance to embolism above -2.7 MPa. Embolism vulnerability was significantly correlated with elevation, mean annual temperature and percentage of species occurrences located in rain forest habitats. Xylem conduit type did not explain variation in P50. Commonly used functional traits such as wood density and leaf traits were not related to embolism vulnerability. Xylem embolism vulnerability stands out among other commonly used functional traits as a major driver of species environmental distribution. Drought-induced xylem embolism vulnerability behaves as a physiological trait closely associated with the habitat occupation of rain forest woody species.
authors.affiliation: IRD, UMR AMAP, BPA5, 98800, Noumea, New Caledonia.
authors.forename: Santiago
authors.initials: S
authors.lastname: Trueba
authors.affiliation: Institut Agronomique néo-Calédonien (IAC), Diversité biologique et fonctionnelle des écosystèmes terrestes, 98848, Noumea, New Caledonia.
authors.forename: Robin
authors.initials: R
authors.lastname: Pouteau
authors.affiliation: Naturalis Biodiversity Center, Leiden University, PO Box 9517, 2300RA, Leiden, The Netherlands.
authors.forename: Frederic
authors.initials: F
authors.lastname: Lens
authors.affiliation: Department of Ecology and Evolutionary Biology, Tulane University, New Orleans, LA, 70118, USA.
authors.forename: Taylor S
authors.initials: TS
authors.lastname: Feild
authors.affiliation: IRD, UMR AMAP, BPA5, 98800, Noumea, New Caledonia.
authors.forename: Sandrine
authors.initials: S
authors.lastname: Isnard
authors.affiliation: Instituto de Biología, Universidad Nacional Autónoma de México, Tercer Circuito s/n de Ciudad Universitaria, México DF, 04510, Mexico.
authors.forename: Mark E
authors.initials: ME
authors.lastname: Olson
authors.affiliation: BIOGECO, INRA-Univ., Bordeaux, 33610, Cestas, France.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Delzon
mesh_terms: D005843:Geography; D062312:Islands; D019684:Magnoliopsida / Q000502:physiology; D009510:New Caledonia; D018515:Plant Leaves / Q000502:physiology; D018547:Plant Stems / Q000502:physiology; D011312:Pressure; D011891:Rain; D065947:Rainforest; D013045:Species Specificity; D014329:Tropical Climate; D052584:Xylem / Q000502:physiology* / Q000648:ultrastructure
keywords: angiosperms; cavitation; drought resistance; elevation; environmental gradients; functional traits; vesselless angiosperms; wood density