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Seasonal changes in tissue‐water relations for eight species of ferns during historic drought in California
Author(s) -
Holmlund Helen I.,
Lekson Victoria M.,
Gillespie Breahna M.,
Nakamatsu Nicole A.,
Burns Amanda M.,
Sauer Kaitlyn E.,
Pittermann Jarmila,
Davis Stephen D.
Publication year - 2016
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.3732/ajb.1600167
Subject(s) - evergreen , biology , chaparral , fern , ecology , desiccation , botany , xylem
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 differential mechanisms of drought survival and physiological performance during extreme water deficits. METHODS: We monitored seasonal changes in water potential ( Ψ md ) and dark‐adapted chlorophyll fluorescence ( F v / F m ), assessed tissue‐water relations including osmotic potential at saturation and the turgor loss point ( Ψ π, sat and Ψ π, tlp ), and measured, for two evergreen species, xylem‐specific and leaf‐specific hydraulic conductivity ( K s and K l ) and vulnerability of stem xylem to water stress‐induced embolism (water potential at 50% loss hydraulic conductivity, Ψ 50 ). 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 50 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.