Plant genome size modulates grassland community responses to multi‐nutrient additions

Abstract

Grassland ecosystems cover c. 40% of global land area and contain c. 40% of soil organic carbon. Understanding the effects of adding nutrients to grasslands is essential because they provide much of our food, support diverse ecosystem services and harbor rich biodiversity.Using the meadow steppe (grassland) study site of Inner Mongolia, we manipulated seven key nutrients and a cocktail of micronutrients to examine their effects on grassland biomass productivity and diversity.The results, explained in structural equation models, link two previously disparate hypotheses in grassland ecology: (1) the light asymmetry competition hypothesis and (2) the genome size-nutrient interaction hypothesis. We show that aboveground net primary productivity increases predominantly from species with large genome sizes with the addition of nitrogen, and nitrogen plus phosphorus. This drives an asymmetric competition for light, causing a decline in species richness mainly in species with small genome sizes.This dynamic is likely to be caused by the nutrient demands of the nucleus and/or the scaling effects of nuclear size on cell size which impact water use efficiency. The model will help inform the best management approaches to reverse the rapid and unprecedented degradation of grasslands globally.

β‐diversity in temperate grasslands is driven by stronger environmental filtering of plant species with large genomes

“…Previous studies have found that large‐GS species became more dominant after nutrient addition for 72 (Šmarda et al, 2013) and 160 years (Guignard et al, 2016) at the time of data analysis, supporting the general pattern across the 10 years of our experiment. More importantly, our results were in line with a recent study conducted also at the Inner Mongolia grassland (Peng et al, 2022), in which the interactions between GS and nutrient addition can influence aboveground net primary producion and the effect was apparent after 1 year of nutrient addition. In addition to the nutrient use or demand, GS directly affects minimum cell size and its variation has consequences for leaf gas exchanges and water use efficiency (Beaulieu et al, 2008; Simonin & Roddy, 2018).…”

“…Indeed, there is evidence that large-GS species became more dominant under conditions with higher nutrient availability (Guignard et al, 2016;Šmarda et al, 2013). Recently, Peng et al (2022) manipulated nutrient availability in the Inner Mongolia grassland and showed that aboveground net primary productivity increased predominantly from large-GS species with the addition of N, and N plus P. Thus, we expect that environmental filtering would have stronger effects on large-GS species than that on small-GS ones.…”

Enhanced foliar 15N enrichment with increasing nitrogen addition rates: Role of plant species and nitrogen compounds

“…The mean annual precipitation and temperature in this area are approximately 360 mm and −2.5°C (1957–2016), respectively (Yang et al, 2019, 2022). The soil is classified as Chernozem with 49.67% sand, 31.57% silt, and 18.76% clay and a pH (0–10 cm) of 6.81 ± 0.09 (Peng et al, 2022), according to the classification by Food and Agricultural Organization (IUSS Working Group WRB, 2015). The soil organic carbon and total nitrogen content, total and available phosphorus concentration in the topsoil (0–10 cm) are 38.27 ± 0.88 g kg −1 , 3.17 ± 0.07 g kg −1 , 401.85 ± 15.50 mg kg −1 , and 5.40 ± 0.25 mg kg −1 , respectively (Peng et al, 2022).…”

“…The soil is classified as Chernozem with 49.67% sand, 31.57% silt, and 18.76% clay and a pH (0–10 cm) of 6.81 ± 0.09 (Peng et al, 2022), according to the classification by Food and Agricultural Organization (IUSS Working Group WRB, 2015). The soil organic carbon and total nitrogen content, total and available phosphorus concentration in the topsoil (0–10 cm) are 38.27 ± 0.88 g kg −1 , 3.17 ± 0.07 g kg −1 , 401.85 ± 15.50 mg kg −1 , and 5.40 ± 0.25 mg kg −1 , respectively (Peng et al, 2022). The growing season in the region extends from June to September, which receives more than 70% of the total annual precipitation.…”

Genome‐material costs and functional trade‐offs in the autopolyploid Solidago gigantea (giant goldenrod) series

“…In contrast, nutrient enrichments may release polyploids from genome‐material‐cost constraints and enhance genetic and phenotypic advantages associated with polyploidy (Faizullah et al, 2021), such as being larger and more competitive (Thébault et al, 2011; Yang et al, 2021). In support of these predictions, studies have found that polyploidy and GS are positively correlated with cellular N and/or P content (Jeyasingh and Weider, 2007; Kang et al, 2015) and that environmental scarcities in N and/or P often favor the growth and fitness of diploids or organisms with smaller genomes, whereas N and/or P enrichments often have opposite effects, favoring the growth and fitness of organisms with larger genomes (Hessen et al, 2013; Neiman et al, 2013; Šmarda et al, 2013; Guignard et al, 2016; Bales and Hersch‐Green, 2019; Walczyk and Hersch‐Green, 2019; Anneberg and Segraves, 2020; Peng et al, 2022). However, a lack of ploidy‐level‐ and GS‐dependent growth responses to nutrient amendments has also been observed (Sánchez Vilas and Pannell, 2017; Walczyk and Hersch‐Green, 2022), suggesting additional factors inherent to specific organisms and their environments likely contribute to realized material costs, selective constraints, and responses to nutrient availabilities.…”