title: A tale of two plasticities: leaf hydraulic conductances and related traits diverge for two tropical epiphytes from contrasting light environments.
abstract: We compared the effects of different light environments on leaf hydraulic conductance (Kleaf ) for two congeneric epiphytes, the tank bromeliads Guzmania lingulata (L.) Mez and Guzmania monostachia (L.) Rusby ex Mez. They occur sympatrically at the study site, although G. monostachia is both wider ranging and typically found in higher light. We collected plants from two levels of irradiance and measured Kleaf as well as related morphological and anatomical traits. Leaf xylem conductance (Kxy ) was estimated from tracheid dimensions, and leaf conductance outside the xylem (Kox ) was derived from a leaky cable model. For G. monostachia, but not for G. lingulata, Kleaf and Kxy were significantly higher in high light conditions. Under both light conditions, Kxy and Kox were co-limiting for the two species, and all conductances were in the low range for angiosperms. With respect to hydraulic conductances and a number of related anatomical traits, G. monostachia exhibited greater plasticity than did G. lingulata, which responded to high light chiefly by reducing leaf size. The positive plasticity of leaf hydraulic traits in varying light environments in G. monostachia contrasted with negative plasticity in leaf size for G. lingulata, suggesting that G. monostachia may be better able to respond to forest conditions that are likely to be warmer and more disturbed in the future.
authors.affiliation: Department of Biology, Occidental College, Los Angeles, CA, 90041, USA.
authors.forename: Gretchen B
authors.initials: GB
authors.lastname: North
authors.affiliation: Department of Biology, Occidental College, Los Angeles, CA, 90041, USA.
authors.forename: Marvin G
authors.initials: MG
authors.lastname: Browne
authors.affiliation: Department of Biology, Occidental College, Los Angeles, CA, 90041, USA.
authors.forename: Kyle
authors.initials: K
authors.lastname: Fukui
authors.affiliation: Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO, 80309, USA.
authors.forename: Franklin D R
authors.initials: FD
authors.lastname: Maharaj
authors.affiliation: Odum School of Ecology, University of Georgia, Athens, GA, 30602, USA.
authors.forename: Carly A
authors.initials: CA
authors.lastname: Phillips
authors.affiliation: Department of Microbiology, University of Georgia, Athens, GA, 30602, USA.
authors.forename: Walter T
authors.initials: WT
authors.lastname: Woodside
mesh_terms: D000220:Adaptation, Biological; D031229:Bromeliaceae / Q000033:anatomy & histology / Q000502:physiology*; D008027:Light; D054046:Plant Stomata / Q000502:physiology; D065947:Rainforest; D014867:Water / Q000502:physiology*; D052584:Xylem / Q000502:physiology*
chemical_list: D014867:Water
keywords: Guzmania lingulata; Guzmania monostachia; Tank bromeliad; leaf anatomy; leaf xylem; sun versus shade leaves