Seasonal changes in tissue-water relations for eight species of ferns during historic drought in California

Department(s)

Natural Science

Document Type

Article

Publication Date

9-1-2016

Keywords

Chlorophyll fluorescence, Ferns, Niche segregation, Osmotic adjustment, Pteridophyte, Water utilization, Xylem embolism

Abstract

PREMISE OF THE STUDY: California experienced severe drought between 2012 and 2016. During this period, we compared seasonal changes in tissue-water relations among eight fern species in the Santa Monica Mountains of southern California to elucidate diff erential mechanisms of drought survival and physiological performance during extreme water deficits. METHODS: We monitored seasonal changes in water potential (Ψ ) and dark-adapted chlorophyll fluorescence (F v/F ), assessed tissue-water relations including osmotic potential at saturation and the turgor loss point (Ψ and Ψ ), and measured, for two evergreen species, xylem-specifi c and leafspecifi c hydraulic conductivity (K and K ) and vulnerability of stem xylem to water stress-induced embolism (water potential at 50% loss hydraulic conductivity, Ψ ). KEY RESULTS: Species grew in either riparian or chaparral understory. The five chaparral species had a wider range of seasonal water potentials, root depths, and frond phenological traits, including one evergreen, two summer-deciduous, and two desiccation-tolerant (resurrection) species. Evergreen species were especially diverse, with an evergreen riparian species maintaining seasonal water potentials above −1.3 MPa, while an evergreen chaparral species had seasonal water potentials below −8 MPa. In those two species the Ψ values were −2.5 MPa and −4.3 MPa, respectively. CONCLUSIONS: Observed differences in physiological performance among eight fern species reflected niche partitioning in water utilization and habitat preference associated with distinct phenological traits. We predict differential survival among fern species as future drought events in California intensify, with desiccation-tolerant resurrection ferns being the most resistant. md m π,sat π,tlp s l 50 50

Publication Title

American Journal of Botany

ISSN

00029122

Volume

103

Issue

9

First Page

1607

Last Page

1617

DOI

10.3732/ajb.1600167

PubMed ID

27638918

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