Mowing exacerbates the loss of ecosystem stability under nitrogen enrichment in a temperate grassland

Abstract

Summary Global reactive nitrogen (N) is projected to further increase in the coming years.Previous studies have demonstrated that N enrichment weakens the temporal stability of the ecosystem and the primary productivity through decreased biodiversity and species asynchrony. Mowing is a globally common practise in grasslands; and infrequent mowing can maintain or increase plant diversity under N enrichment conditions. However, it is unclear how infrequent mowing affects ecosystem stability in the face of N enrichment. 2.By independently manipulating the frequency (twice vs. monthly additions per year) and rate (i.e. 0, 1, 2, 3, 5, 10, 15, 20, and 50 g N m −2 year −1 ) of NH 4 NO 3 inputs and mowing (unmown vs. mown) over 3 years (2011)(2012)(2013) in a temperate grassland of northern China, we aimed to examine the interactive effects of N enrichment and mowing on ecosystem stability. 3.The results show that mowing maintained a positive relationship between species richness and ecosystem stability despite N addition, but that it exacerbated the negative effects of N addition on ecosystem stability. Mowing increased mean primary productivity and plant species richness, but it also increased the synchrony of population fluctuations and the variability of primary productivity under N enrichment, thereby contributing to a decline in the ecosystem stability. Data accessibilityData deposited in the Dryad Digital Repository: https://dx.doi.org/10.5061/dryad.sq15g (Zhang et al. 2017).The authors declare that they have no competing interests. 4. Thus, our study reveals that infrequent mowing can buffer the negative effects of N enrichment on biodiversity to some extent and further increase the primary productivity, but it exacerbates the loss of ecosystem stability with N enrichment, thereby threatening local and/or semiarid regional food security. Europe PMC Funders Group

Nitrogen addition does not reduce the role of spatial asynchrony in stabilising grassland communities

“…This experiment was initially designed to assess how the frequency and rate of N addition affect grassland community structure and ecosystem functioning (Zhang et al . , , ,b, ), and is used here to explore how increased N deposition influences ecosystem stability across spatial scales.…”

Effects of Climate Change on Grassland Biodiversity and Productivity: The Need for a Diversity of Models

“…Most of the ground-breaking experiments on vegetation biodiversity from the 1980s onward were and are being carried out in grasslands because of the convenient size and lifespan of grassland species [58]. These experiments have primarily focused on the relation between the number of grass species in swards and the magnitude and stability of primary productivity (e.g., [59]), with some experiments looking at the impact of water or nutrient availability on this relationship [60], and interactions with mowing [61,62]. In a meta-analysis of 44 grassland biodiversity experiments [63], it was found that different grassland species tended to complement each other, leading to increased productivity in polycultures compared to monocultures.…”

Scale dependence of the diversity–stability relationship in a temperate grassland

“…Many studies have demonstrated that species richness enhances ecosystem stability (as measured by the inverse of the temporal variability in its aggregate properties) in both experimental and natural communities at small spatial scales (Bai, Han, Wu, Chen, & Li, 2004;Hautier et al, 2015;Hector et al, 2010;Jiang & Pu, 2009). They show that species richness promotes the stability of productivity at local scales, mainly through the insurance effect (species asynchrony or compensation) (Bai et al, 2004;Loreau & de Mazancourt, 2013;Yachi & Loreau, 1999;Zhang, Loreau, He, Zhang, & Han, 2017b) and overyielding (Hector et al, 2010;Tilman, Reich, & Knops, 2006).…”