Timing and duration of precipitation pulses and interpulses influence seedling recruitment in the Great Basin

Authors: PYLE, LYSANDRA - University Of California Agriculture And Natural Resources (UCANR); Sheley, Roger; JAMES, JEREMY - University Of California Agriculture And Natural Resources (UCANR)

Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/9/2020
Publication Date: 1/19/2021
Citation: Pyle, L.A., Sheley, R.L., James, J.J. 2021. Timing and duration of precipitation pulses and interpulses influence seedling recruitment in the Great Basin. Rangeland Ecology and Management. 75:112-118. https://doi.org/10.1016/j.rama.2020.12.004.
DOI: https://doi.org/10.1016/j.rama.2020.12.004

Interpretive Summary: Restoring rangeland is central to recreating healthy functioning plant communities in areas that have been degraded and invaded. The most limiting stage of establishing native plants during restoration is emergence. We studied the influence of intermittent wetting and drying on seedling establishment. Not surprisingly, as dry conditions combine with longer dry intervals emergence was lower. The most novel information was that dry periods in late-winter control emergence more than dry periods during early-spring. As we develop weather-centric restoration strategies, this information will be helpful in determine when reseeding should occur during restoration.

Technical Abstract: Precipitation pulses and interpulse dry periods are major drivers of dryland ecosystem function yet how the patterning and timing of precipitation inputs and dry periods influences seedling recruitment in these systems is poorly understood. We conducted two experiments to understand how limited and variable patterns of precipitation inputs may influence recruitment of bluebunch wheatgrass [Pseudoroegneria spicata ((Pursh) A. Löve)]. In the first experiment we evaluated how precipitation magnitude and dry day interval during spring influenced recruitment. All ambient precipitation was excluded during spring and we experimentally applied 5 levels of water (25, 35, 45, and 65 mm) and 5 dry day durations (1, 2, 4, 6, or 8 dry days between waterings) to plots sown with P. spicata. In the second experiment, we evaluated how the seasonal timing and duration of dry days influenced recruitment. All ambient precipitation was excluded through late winter and spring and we experimentally applied three levels of dry day duration (10, 20, and 30 days) four times during the growing season (Feb, Mar, Apr, and May) to plots sown with P. spicata. We observed strong, non-linear interactive effects of precipitation amount and dry-day interval on recruitment where the mid point dry-day treatment (4 d) interacted with low water availability to drive a major decline in recruitment. We also found strong evidence that recruitment was limited by dry periods occurring in late winter as opposed to dry periods occurring on through spring with recruitment decreasing over 40% during February dry periods compared to dry periods in March, April or May. By understanding how precipitation pulses and interpulse dry periods interact to drive recruitment we can refine efforts to develop weather-centric restoration frameworks, as well as hone ongoing efforts to identify plant materials and seed enhancement technologies that may buffer effects of variable precipitation on recruitment.