DOI: 10.5068/d1409q
title: Flowering phenology for seven California annual species under two rainfall treatments

description: 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 phenology of some species, but sensitivity differed
 among neighboring species. Four of the seven species studied started
 and/or peaked flowering earlier in response to reduced water availability.
 The idiosyncratic shifts in flowering phenology have the potential to
 alter existing temporal dynamics that may be maintaining coexistence, such
 as temporal separation of resource-use among neighbors. Conclusions: Our
 results show how species-specific phenological consequences of global
 change can impact community dynamics and competition between neighboring
 plants and warrant future research.
description: 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
 plot to identify the flowering window for each species (i.e. first and
 last days of flowering). We then counted the number of flowers in the
 photos over that time period, avoiding images that were obscured by
 condensation, rain, or wind-driven camera and plant movement. This
 resulted in counts of open flowers every 1 to 5 days for each species
 during their flowering period. The plots were also visited in person every
 two weeks and every flowering individual was identified and
 counted. 
description: # 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
 ([mary.vandyke@colostate.edu](mailto:mary.vandyke@colostate.edu)) 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 7 annual plant species under two
 precipitation treatments. All data was collected by the authors. |
 variables | units | description | | | :-------- | :---------: |
 :--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | :- | | species | categorical | species codes for 7 species: ACWR = Acmispon wrangelianus, FEMI = Festuca microstachys, HOMU = Hordeum murinum, LACA = Lasthenia californica, NAAT = Navarretia atractyloides, PLER = Plantago erecta, URLI = Uropappus lindleyi californica | | | plot | number | plots are numbered 1 through 20 | | | block | number | there were ten blocks which each included two plots of the same precipitation treatment | | | treatment | categorical | precipitation treatment, c = control, s = shelter | | | doy | number | day of year with January 1, 2020 as 1 | | | flower | number | number of flowers in bloom within the plot | | ## sedg\_rain\_2020.csv This file contains rainfall data collected at the experimental site from October, 2019 to August, 2020. | variables | units | description | | :--------------- | :----: | :-------------------------------------------------------------------------------------------------------------------------------------------------------------- | | year | number | year data was collected - always 2020 | | month | number | month data was collected | | day | number | day of the month data was collected | | rain\_cumulative | number | cumulative rainfall on ambient plots in mm since October 1, 2019 | | d\_o\_y | number | day of year with January 1, 2020 as 1 | | selter\_rain | number | cumulative rainfall on reduced rainfall plots since October 1, 2019, assuming a 50 percent reduction after February 8, 2020 when rainout shelters were erected. | ## boots\_pairs\_w\_sup.csv This file contains competition parameter estimates from previous experiment performed in the 2019 growing season. | variables | units | description | | | :----------- | :---------: | :---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | :- | | focal | categorical | species codes for 7 species, ACWR = Acmispon wrangelianus, FEMI = Festuca microstachys, HOMU = Hordeum murinum, LACA = Lasthenia californica, NAAT = Navarretia atractyloides, PLER = Plantago erecta, URLI = Uropappus lindleyi californica | | | competitor | categorical | species codes for 7 species, same codes as focal variable | | | treatment | categorical | precipitation treatment, c = control (ambient), s = shelter (reduced rain) | | | snd | number | estimated stabilizing niche difference between the pair of species | | | fd\_superior | number | estimated fitness difference between the pair | | ## All phenology data was collected in person and from photographs in the spring of 2020 from Sedgwick reserve in Santa Barbara county, CA Code files include: ## boots\_final.R all code needed for analysis, need to run this before running either of the figure scripts ## final\_figures.R code needed to create figures in the manuscript ## supplemental\_figures.R code needed for all figures in supplementary material appendix 1