Nutrient stoichiometry and land use rather than species richness determine plant functional diversity

Abstract

Plant functional traits reflect individual and community ecological strategies. They allow the detection of directional changes in community dynamics and ecosystemic processes, being an additional tool to assess biodiversity than species richness. Analysis of functional patterns in plant communities provides mechanistic insight into biodiversity alterations due to anthropogenic activity. Although studies have consi‐dered of either anthropogenic management or nutrient availability on functional traits in temperate grasslands, studies combining effects of both drivers are scarce. Here, we assessed the impacts of management intensity (fertilization, mowing, grazing), nutrient stoichiometry (C, N, P, K), and vegetation composition on community‐weighted means (CWMs) and functional diversity (Rao's Q) from seven plant traits in 150 grasslands in three regions in Germany, using data of 6 years. Land use and nutrient stoichiometry accounted for larger proportions of model variance of CWM and Rao's Q than species richness and productivity. Grazing affected all analyzed trait groups; fertilization and mowing only impacted generative traits. Grazing was clearly associated with nutrient retention strategies, that is, investing in durable structures and production of fewer, less variable seed. Phenological variability was increased. Fertilization and mowing decreased seed number/mass variability, indicating competition‐related effects. Impacts of nutrient stoichiometry on trait syndromes varied. Nutrient limitation (large N:P, C:N ratios) promoted species with conservative strategies, that is, investment in durable plant structures rather than fast growth, fewer seed, and delayed flowering onset. In contrast to seed mass, leaf‐economics variability was reduced under P shortage. Species diversity was positively associated with the variability of generative traits. Synthesis. Here, land use, nutrient availability, species richness, and plant functional strategies have been shown to interact complexly, driving community composition, and vegetation responses to management intensity. We suggest that deeper understanding of underlying mechanisms shaping community assembly and biodiversity will require analyzing all these parameters.

Will I stay or will I go? Plant species‐specific response and tolerance to high land‐use intensity in temperate grassland ecosystems

“…This is in line with the overall loss of species richness along increasing gradients of compound land‐use ( ρ = −0.415, p < 0.001), mowing ( ρ = −0.399, p < 0.001) and fertilization intensity ( ρ = −0.285, p < 0.001). Many studies corroborate our results, showing plant species richness decreasing strongly especially due to the intensification of fertilization (e.g., Kleinebecker et al., ; Zechmeister et al., ), mowing or combined effects (Busch et al., ; Socher et al., ).…”

“…All of them can have great impact on distribution, establishment and survival of grassland species (Allan et al., ; Díaz et al., ; Drobnik et al., ; Jongman, ). However, a previous study showed that the effects of climatic, topographic and edaphic parameters on community‐weighted mean values of plant traits were less important, whilst land use and nutrient stoichiometry had the greatest impact (Busch et al., ).…”

“…The assembly, coexistence and persistence of plant species along environmental gradients and the occupation of available ecological niches are based on the species’ responses to disturbance and stress (Silvertown, ). These responses are, for instance, driven by species‐specific life‐history traits and ecological strategies for acquiring and using resources or for tolerating or avoiding disturbance (Busch et al., ; Devictor et al., ; Hodgson, Wilson, Hunt, Grime, & Thompson, ).…”

Anthropogenic global shifts in biospheric N and P concentrations and ratios and their impacts on biodiversity, ecosystem productivity, food security, and human health

“…For example, the typically negative relationships between N:P ratios and the diversities of zoo-and phytoplankton (He et al, 2013) are associated with the shortened pathways and lower transfer rates of matter and energy along trophic webs under P limitation (Elser et al, 2000). Nutrient limitation and high N:P ratios are consistently associated with shifts from fast-to slow-growing species in all types of media (Busch et al, 2018;Penuelas et al, 2013), and soil microbial and decomposer faunal compositions are consistently associated with soil and litter N:P ratios (Barantal, Schimann, Fromin, & Hättenschwiler, 2014;Delgado-Baquerizo et al, 2017;Eo & Park, 2016;Lee et al, 2015Lee et al, , 2017Leflaive et al, 2008;Ren et al, 2017;Su et al, 2015).…”

Effects of mowing, grazing and fertilization on soil seed banks in temperate grasslands in Central Europe

“…Management effects are likely to be indirect via shaping the aboveground vegetation by applying certain management techniques such as mowing and grazing, which will influence seed banks differently as time and manner of harvest (biomass removal) decide whether seed set is successful and species can contribute seeds to the seed bank or not (Bekker et al, 1997;Wellstein et al, 2007). Fertilization might have two opposing effects on soil seed banks, as on the one hand the addition of further nutritional resources enables plants to invest more in sexual reproduction, but on the other hand fertilization also shifts the aboveground community towards highly productive grass, which are known to poorly contribute to a persistent seed bank (Busch et al, 2017;Thompson and Grime, 1979). Thus, not just presence or absence of a factor, i.e.…”