Flowering phenology for seven California annual species under two rainfall treatments

Premise: Shifts in the timing of life history events, or phenology, have been recorded across many taxa and biomes in response to global change. These phenological changes are often studied in a single species context, but considering the community context is essential for anticipating the cascading effects on biotic interactions that are likely to occur. Focusing on an annual grassland plant community, we examined how experimental changes in precipitation affect flowering phenology in a community context and explore the implications of these shifts for competitive interactions and species coexistence.
Methods: We experimentally manipulated rainfall with rainout shelters and recorded detailed flowering phenology data for seven annual species including two grasses and five forbs. We assessed how their first and peak flowering days were affected by changes in rainfall and explored how flowering overlap between competing species changed.
Results: Changes in rainfall shifted flowering pheno..., The experiment was conducted at the University of California, Santa Barbara’s Sedgwick Reserve in Santa Barbara County, USA. Twenty 0.75m*0.75m plots were established and seeded in October 2019 in a fenced area designed to exclude deer and gophers, the two primary mammalian herbivores in the system. One hundred seeds of seventeen cooccuring annual grasses and forbs were mixed and hand sown in each plot. The plots were paired into ten blocks. Rain reduction shelters designed to divert 50% of incoming rain were placed over five of the blocks and therefore half of the plots on February 8, 2020. This timing allowed all plants to germinate and establish in late December and January with the same ambient rainfall conditions, resulting in the rainfall exclusion treatment impacting just the growth and reproduction phase of the plants’ life cycle. The seven most abundent species that germinated were tracked over the course of their lifetime. We used daily photographs from cameras mounted at each..., , # Flowering phenology for seven California annual species under two rainfall treatments

This is the data and analysis code for the manuscript entitled, \"Changes in flowering phenology with altered rainfall and the potential community impacts in an annual grassland.\" It includes the number of flowers visible for 7 annual plant species (5 forbs, 2 grasses), grown in mixed competition plots under two precipitation periods during the 2020 growing season.

Contact Mary Van Dyke ([[e-mail]](mailto:[e-mail])) with any questions. This manuscript has been accepted for publication in the American Journal of Botany (1/15/2025):
Van Dyke, M.N., N.J.B. Kraft. Changes in flowering phenology with altered rainfall and the potential community impacts in an annual grassland. American Journal of Botany (accepted).

There are three data files and three R scripts

Data files include:

## all\_species\_flower\_data.csv

This file contains the flowering phenology data for ...,