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ARS Home » Pacific West Area » Logan, Utah » Forage and Range Research » Research » Publications at this Location » Publication #326504
Title: Altered precipitation patterns and simulated nitrogen deposition effects on phenology of common plant species in a Tibetan Plateau alpine meadow

Author
item LIU, LIN - Sichuan University
item Monaco, Thomas
item SUN, FEIDA - Sichuan University
item LIU, WEI - Sichuan University
item GAN, YOUMIN - Sichuan University
item SUN, GENG - Chinese Academy Of Sciences

Submitted to: Agricultural and Forest Meteorology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/12/2017
Publication Date: 4/15/2017
Citation: Liu, L., Monaco, T.A., Sun, F., Liu, W., Gan, Y., Sun, G. 2017. Altered precipitation patterns and simulated nitrogen deposition effects on phenology of common plant species in a Tibetan Plateau alpine meadow. Agricultural and Forest Meteorology.

Interpretive Summary: The interactive effects of five seasonal precipitation distribution patterns and two levels of N deposition (ambient and doubled) on phenological traits of six dominant plant species were studied in an alpine meadow of the Tibetan Plateau for two consecutive years. Seasonal precipitation patterns included ambient (control), reduced fall/winter/spring - increased summer, increased fall/winter - reduced spring, increased fall/winter - reduced spring/summer, and increased spring - reduced summer. Our results indicate that: 1) phenological trait variation was predominantly due to species differences (P<0.0001), yet flowering dates for annual forbs and perennial graminoids were more synchronous under wetter conditions in the second season, which likely led to more intense competition for soil resources between these two groups; 2) treatment effects on species phenological traits appeared in the second growing season only, suggesting that phenological shifts in these species lag behind abiotic conditions and/or require cumulative exposure to these factors (>2 years); 3) redistributing dormant season and spring precipitation to summer caused earlier flowering for the grass P. pratensis, earlier and shorter duration of fruiting for the annual forb G. paludosa, and lengthened the flowering of the perennial grass K. setchwanensis; yet N addition diminished and/or reveresed these effects. Moreover, augmenting fall and winter precipitation at the expense of spring and summer precipitation decreased all phenological traits of P. anserina except for flowering date, but N addition reversed these effects, and; 4) interannual variation in species phenology was strongly influenced by environmental differences among the two growing seasons rather than different precipitation patterns and N addition. We discuss how seasonal shifts in precipitation and/or greater N deposition in the future may impact plant species fitness, species coexistence, and vegetation composition in alpine meadow ecosystems of the Tibetan Plateau.

Technical Abstract: The interactive effects of five seasonal precipitation distribution patterns and two levels of N deposition (ambient and doubled) on phenological traits of six dominant plant species were studied in an alpine meadow of the Tibetan Plateau for two consecutive years. Seasonal precipitation patterns included ambient (control), reduced fall/winter/spring - increased summer, increased fall/winter - reduced spring, increased fall/winter - reduced spring/summer, and increased spring - reduced summer. Our results indicate that: 1) phenological trait variation was predominantly due to species differences (P<0.0001), yet flowering dates for annual forbs and perennial graminoids were more synchronous under wetter conditions in the second season, which likely led to more intense competition for soil resources between these two groups; 2) treatment effects on species phenological traits appeared in the second growing season only, suggesting that phenological shifts in these species lag behind abiotic conditions and/or require cumulative exposure to these factors (>2 years); 3) redistributing dormant season and spring precipitation to summer caused earlier flowering for the grass P. pratensis, earlier and shorter duration of fruiting for the annual forb G. paludosa, and lengthened the flowering of the perennial grass K. setchwanensis; yet N addition diminished and/or reversed these effects. Moreover, augmenting fall and winter precipitation at the expense of spring and summer precipitation decreased all phenological traits of P. anserina except for flowering date, but N addition reversed these effects, and; 4) interannual variation in species phenology was strongly influenced by environmental differences among the two growing seasons rather than different precipitation patterns and N addition. We discuss how seasonal shifts in precipitation and/or greater N deposition in the future may impact plant species fitness, species coexistence, and vegetation composition in alpine meadow ecosystems of the Tibetan Plateau.