Belowground traits and biomass data from California grassland in 2015

Understanding precipitation controls on functional diversity is important in predicting how change in rainfall patterns will alter plant productivity in the future. Trait-based approaches can provide predictive knowledge about how certain species will behave and interact with the community. However, how functional diversity relates to above- and belowground biomass production in variable rainfall conditions remains unclear.
Here, we tested the role of mass ratio and niche complementarity hypotheses in shaping above- and belowground biomass-functional diversity relationships in seasonal drought. We implemented a fully crossed experiment that manipulated drought timing (fall dry, spring dry, consistent dry, and ambient rainfall) and community composition (grass-dominated, forb-dominated, and mixed grass-forb) in a California annual grassland.
Plant communities with mixed functional groups showed higher above- and belowground biomass than either the grass- or forb-dominant communities.
We..., This study was conducted at the University of California Sierra Foothills Research and Extension Center (SFREC), which is located north of Sacramento in Browns Valley, California (39º15’ N, 121º17’ W).
Experimental Design
In October 2014, we set up an experiment that manipulated the quantity and timing of rain and the plant community composition (Hallett et al., 2019; Shaw et al., 2022). We did not need permits for fieldwork. Water year 2015 (October 2014 to May 2015) was the final year of a 6-year drought, among the worst on state record since record-keeping began in 1895 in California (California Department of Water Resources 2017). In a random-block design, plant community composition treatments were nested within rainfall treatment plots in 4 blocks (Fig. S1). Rainfall treatments consisted of control (ambient rainfall), consistent dry (50% of rain blocked from October–May), fall dry (50% of rain blocked from October–January), and spring dry (50% of rain blocked from February–May). A...,