Seasonality regulates the effects of resource addition on plant diversity and ecosystem functioning in semi-arid grassland

Abstract

Aims Seasonal variations in species richness, aboveground net primary productivity (ANPP), and stability under resource enrichment are frequently ignored. This study explores how the impacts of resource enrichment on species richness, ANPP, and stability vary among seasons in semi-arid grasslands. Methods We conducted a three-year experiment in an Inner Mongolia grassland to determine the effects of resource input (water [W], nitrogen [N]) on species richness, community ANPP, and stability using seasonal sampling during the growing season (2013–2015). Structural equation modelling (SEM) was used to examine the relative importance of resource input on community stability via mechanistic pathways in each month and the whole growing season. Important Findings Resource inputs did not affect community ANPP in May and June, while N and/or NW enhanced ANPP in July and August. Resource inputs generally did not affect species richness, asynchrony, or community stability in most of the time. Positive responses of perennial bunchgrasses (PB) to N and/or NW treatments contributed to the increased community ANPP in July and August. Species asynchrony may be the major mechanism contributing to community stability in May and June and the entire growing season, and PB stability is potentially the primary factor controlling community stability in July and August under resource enrichment. Our results indicate that season and resource availability could interact to regulate species richness, community ANPP, and stability in semi-arid grasslands. These findings have important implications for management practices in semi-arid grasslands in order to mitigate the impact of land use and global change.

Independent biodiversity mechanisms regulate ecosystem multifunctionality and its temporal stability under resource enrichment in a mown grassland

“…Surprisingly, SE did not weaken the stability of ecosystem multifunctionality, which is inconsistent with our Hypothesis 3. This is because the increase in community productivity under resource addition was attributed to the increase in species with stable abundance under interannual climate variations, rather than species with high variation (Xu et al., 2021).…”

“…Theoretically, species asynchrony stabilizes ecosystem functioning through the temporal asynchronous responses of community species to environmental fluctuations (Loreau & de Mazancourt, 2008). Xu et al (2021) reported that the temporal asynchronous responses of dominant species to environmental fluctuations may be a primary driver of temporal stability in community productivity in a similar community. An integrated analysis across the Mongolia plateau further confirms this mechanism (Wang et al, 2020), suggesting that the CE among dominant species potentially contributes to the temporal stability of ecosystem multifunctionality.…”

Opposing responses of temporal stability of aboveground and belowground net primary productivity to water and nitrogen enrichment in a temperate grassland

“…However, most of plant‐oriented studies, irrespective of theoretical models, observations, and experiments, have focused on the stability of plant ANPP (or its proxies) and the stability of BNPP has received surprisingly less attention. Despite the projected simultaneous increases in nitrogen deposition and precipitation in many regions of the world (IPCC, 2021), as well as the frequently reported interactive effects of nitrogen and water on plant community productivity in terrestrial ecosystems (Kazanski et al., 2021; Shen et al., 2021; Xu, Li, et al., 2021), few studies have simultaneously considered the effects of nitrogen and water addition on ecosystem stability (but see Xu et al., 2015; Wen et al., 2023), and their combined and interactive effects on belowground stability have never been explored. Here, we provided the first evidence on responses of both ANPP and BNPP stability to water and nitrogen addition.…”