DOI: 10.6084/m9.figshare.8298266
title: Hallett_avena-erodium.csv

description: Dataset to accompany the paper “Rainfall variability maintains grass-forb coexistence” by Lauren M. Hallett, Lauren G. Shoemaker, Caitlin T. White and Katharine N. Suding in <i>Ecology Letters</i> (manuscript number ELE-00234-2019.R2)<br> Experimental overview In fall 2014 we established four rainfall treatments in a random-block design, with plots arranged in a single row from east to west. Blocks were replicated four times for a total of 16 plots. Early-season rainfall in this system is thought to primarily affect recruitment, whereas late-season rainfall primarily affects growth. To isolate the effect of drought on periods of recruitment versus growth, our rainfall treatments consisted of early-season fall dry, late-season spring dry, consistent dry, and a consistent wet control. Dry treatments were achieved using 6.4 m x 5.2 m cold frame rainout shelters with clear polyethylene retractable roofs. We erected the roofs shortly before rainfall events, and removed them afterward to minimize their effect on solar radiation. Following the first germinating rains, we experimentally created our rainfall treatments by applying the roofs in some seasons and not others, with a goal of reducing precipitation by 50% during target seasons. To create early-season fall dry we applied roofs during storms from Oct-Jan, for late-season spring dry from Feb-Apr, and for consistent dry from Oct-Apr. Within each main plot we manipulated the seeding density and ratio of the dominant grass <i>Avena barbarta </i>to the dominant forb <i>Erodium botrys</i> to assess the recruitment and growth dynamics of each species when it was rare versus common. Prior to treatment implementation, we reduced the extant seed bank by removing the existing vegetation and upper ~3 cm of top soil. We seeded at two total densities on a log-scale: low (320 seeds/m<sup>2</sup>) and high (similar to observed stem densities, 3200 seeds/m<sup>2</sup>). At each density we manipulated the seeding ratio of <i>Avena </i>to <i>Erodium </i>to capture a range from rare to common (0:10, 1:9, 5:5, 9:1, and 10:0 <i>Avena</i>: <i>Erodium</i>). This yielded a total of 10 25 x 25 cm subplots per main rainfall plot for a total of 160 subplots. We measured initial recruitment by counting stems by species in December, and we measured fecundity by counting species' seed production in the spring. To account for differences in phenology we measured <i>Erodium</i> fecundity in late March and <i>Avena</i> in late April. Both species retain evidence of seed production following seed release <i>Erodium </i>retains its sepals and <i>Avena</i> its spikelets). Consequently, we measured fecundity toward the end of seed production and multiplied each indicator by accordant seeds produced (5 seeds are produced per <i>Erodium </i>flower head and 2 per <i>Avena</i> spikelet). Column metadata shelterBlock: The block in which rainfall treatments were grouped, values range from A-D. plot: The rainfall manipulation plot, values range from 1-16. subplot: The vegetation manipulation subplot nested within rainfall treatment. Names are a combination of density (D1 or D2), and the ratio of Avena to Erodium. treatment: The rainfall treatment. Values include consistentDry (shelters blocked storms throughout the year), fallDry (shelters blocked storms in the fall), springDry (shelters blocked storms in the spring), and controlRain (no shelters). density: The seeding density treatment. Values include Low density (320 seeds/m<sup>2</sup>) and High density (3200 seeds/m<sup>2</sup>). ERprop: The proportion of <i>Erodium </i>seeds added. AVprop: The proportion of <i>Avena </i>seeds added. ERseedin: The number of <i>Erodium </i>seeds added per 25 x 25 cm subplot. ERstem: The number of <i>Erodium </i>stems that recruited in December per 25 x 25 cm subplot. ERseedout: The number of <i>Erodium </i>seeds produced per 25 x 25 cm subplot. AVseedin: The number of <i>Avena </i>seeds added per 25 x 25 cm subplot. AVstem: The number of <i>Avena </i>stems that recruited in December per 25 x 25 cm subplot. AVseedout: The number of <i>Avena </i>seeds produced per 25 x 25 cm subplot.