title: Enhanced monsoon precipitation and nitrogen deposition affect leaf traits and photosynthesis differently in spring and summer in the desert shrub Larrea tridentata.
abstract: Leaf-level CO2 assimilation (A(area)) can largely be predicted from stomatal conductance (g(s)), leaf morphology (SLA) and nitrogen (N) content (N(area)) in species across biomes and functional groups. The effects of simulated global change scenarios, increased summer monsoon rain (+H2O), N deposition (+N) and the combination (+H2O +N), were hypothesized to affect leaf trait-photosynthesis relationships differently in the short- and long-term for the desert shrub Larrea tridentata. During the spring, +H2O and +H2O +N plants had lower A(area) and g(s), but similar shoot water potential (Psi(shoot)) compared with control and +N plants; differences in A(area) were attributed to lower leaf N(area) and g(s). During the summer, +H2O and +H2O +N plants displayed higher A(area) than control and +N plants, which was attributed to higher Psi(shoot), g(s) and SLA. Throughout the year, A(area) was strongly correlated with g(s) but weakly correlated with leaf N(area) and SLA. We concluded that increased summer monsoon had a stronger effect on the performance of Larrea than increased N deposition. In the short term, the +H2O and +H2O +N treatments were associated with increasing A(area) in summer, but also with low leaf N(area) and lower A(area) in the long term the following spring.
authors.affiliation: Department of Biological Sciences, University of Nevada Las Vegas, Las Vegas, NV 89154-4004, USA. barkerd@unlv.nevada.edu
authors.forename: D H
authors.initials: DH
authors.lastname: Barker
authors.forename: C
authors.initials: C
authors.lastname: Vanier
authors.forename: E
authors.initials: E
authors.lastname: Naumburg
authors.forename: T N
authors.initials: TN
authors.lastname: Charlet
authors.forename: K M
authors.initials: KM
authors.lastname: Nielsen
authors.forename: B A
authors.initials: BA
authors.lastname: Newingham
authors.forename: S D
authors.initials: SD
authors.lastname: Smith
mesh_terms: D002245:Carbon Dioxide / Q000378:metabolism; D032442:Larrea / Q000033:anatomy & histology / Q000254:growth & development / Q000378:metabolism*; D009584:Nitrogen / Q000378:metabolism*; D010788:Photosynthesis / Q000502:physiology*; D018515:Plant Leaves / Q000033:anatomy & histology / Q000254:growth & development / Q000378:metabolism; D011891:Rain; D012621:Seasons; D014867:Water / Q000378:metabolism
chemical_list: D014867:Water; D002245:Carbon Dioxide; D009584:Nitrogen