Assessing the roles of nitrogen, biomass, and niche dimensionality as drivers of species loss in grassland communities

Band, Nir; Kadmon, Ronen; Mandel, Micha; DeMalach, Niv

doi:10.1073/pnas.2112010119

Cited by 37 publications

(47 citation statements)

References 201 publications

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“…Briefly, N or P addition and soil acidification made grasses more competitive than forbs and legumes (and also forbs more competitive than legumes), while K or NaMg addition made legumes more competitive than forbs and grasses. Clearly, the findings are in line with the abundance changes of the three functional groups generally observed in many fertilization experiments (6, 39). Thus, absolute competitive differences (together with r ) effectively explained species richness, which provides additional quantitative evidence for the competitive asymmetry and soil acidification hypotheses.…”

Section: Discussionsupporting

confidence: 88%

“…Moreover, our study explicitly demonstrated that existence and coexistence both played a critical role in the process of species loss under nutrient enrichment. All this provides rigorous and quantitative explanations for the general findings in numerous nutrient-addition experiments (see a new meta-analysis, Band et al 2022). In total, our study advances the knowledge of the fundamental mechanisms driving the response of plant diversity to nutrient deposition in nature.…”

Section: Discussionmentioning

confidence: 65%

“…In theory, nutrient enrichment could disrupt the balance to cause species loss by either decreasing niche differences or intensifying competitive asymmetries. The niche dimension hypothesis stresses the former (7), but it has been questioned whether the “hypothetical” niche dimensions (sensu 13) could indeed be reduced with nutrient addition (6, 18). Our study clearly demonstrated that niche differences did not decrease and even tended to increase with nutrient addition, so did structural niche differences.…”

Section: Discussionmentioning

confidence: 99%

“…Along with accelerating anthropogenic activities across the globe, nutrient deposition has increasingly posed one of the major threats to the biodiversity, structure and stability of natural ecosystems (1-3). For example, numerous studies have shown that addition of various nutrients (e.g., N, P, K and trace elements) causes the decline of plant diversity globally in different types of grasslands (4-6). Thus far, three main hypotheses have been proposed to account for this general phenomenon, i.e., niche dimension hypothesis (7), competitive asymmetry hypothesis (8, 9) and soil acidification hypothesis (10).…”

Section: Introductionmentioning

confidence: 99%

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Species existence and coexistence under nutrient enrichment in the Park Grass

Yao

Feng

2022

Preprint

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Numerous studies have shown that nutrient enrichment causes the loss of plant diversity in different grasslands across the globe. Thus far, three main hypotheses (niche dimension, competitive asymmetry, and soil acidification) have been proposed to account for this general phenomenon, but our knowledge of the underlying mechanisms remains rather vague. To reveal the cryptic mechanisms, we analyzed the famous long-term Park Grass Experiment (1856-) under modern coexistence theory by fitting Lotka-Volterra competition models with time-series data from the different treatments (15 different combinations of nutrient addition fully crossed with four levels of soil pH) to quantitatively test the three competing hypotheses. Supportive of the competitive asymmetry and soil acidification hypotheses, both nutrient addition and soil acidification overall decreased intrinsic population growth rates (r) and intensified competitive differences or asymmetries dramatically, which mostly favored grasses over forbs and legumes (and also forbs over legumes). These changes in r and competitive differences or asymmetries are generally consistent with the abundance changes of different functional groups following the various treatments. Moreover, the altered r (determining species existence) and competitive differences (affecting species coexistence) effectively explained the diversity loss and recovery (after nitrogen addition was withheld). However, while nutrient addition significantly decreased per-capita intra- and inter-specific competition (which indicates that belowground competition becomes less intense when soil nutrients are more abundant), it did not decrease niche differences as predicted, poorly supporting the niche dimension hypothesis. These findings advance our understanding of fundamental mechanisms driving the response of plant communities to nutrient deposition in nature.

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Section: Discussionsupporting

confidence: 88%

Section: Discussionmentioning

confidence: 65%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Species existence and coexistence under nutrient enrichment in the Park Grass

Yao

Feng

2022

Preprint

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“…Similar results were obtained in Germany [ 12 ], where soil pH, P, and Mg are drivers of species composition and richness in semi-natural grasslands. However, a recent study stated that N was more important than P and K as a driver of species loss [ 13 ]. Therefore, eutrophication is a major driver of species loss in semi-natural grasslands.…”

Section: Introductionmentioning

confidence: 99%

A single application of fertilizer can affect semi-natural grassland vegetation over half a century

et al. 2022

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Restoration of species-rich semi-natural grassland requires not only a seed source but also appropriate soil properties. In Europe, approximately 10 years are required for the properties of fertilized soils to reach suitable conditions and be considered successfully restored. However, restoration may require additional time in Japan because heavier precipitation causes leaching of basic cations from soils, resulting in soil acidification; volcanic ejecta also forms active Al and Fe hydroxides with high phosphate sorption. Within this context, we aimed to answer the following questions: i) whether and how the impacts of fertilization remain in the soil properties after half a century in Japan; and ii) how fertilization affects the restoration of semi-natural grasslands in Japan. We investigated the vegetation and soil properties of a Zoysia japonica pasture improved half a century ago with a single application of fertilizer and an adjacent semi-natural grassland (native pasture) in Japan, and found the following: (1) the two pastures had similar dominance of Z. japonica, but differed in the species composition; (2) the improved pasture exhibited lower species richness than the native pasture; (3) soil nutrients, including N, P, K, Mg, and Ca, were higher in the improved pasture than in the native pasture; and (4) many chemical properties of the soils were associated with species composition; namely, the vegetation on nutrient-rich soil had more alien species and fewer native species. We conclude that a single dose of fertilization can affect soil properties in semi-natural grasslands over half a century in Japan, leading to species loss and changing the species composition. We suggest that fertilized soils under grazing in Japan may require more than half a century to restore the nutrients to suitable levels for the establishment of a species-diverse grassland.

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Fitness and niche differences are both important in explaining responses of plant diversity to nutrient addition

Dostál

2023

Ecology

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Plant species loss due to eutrophication is a common phenomenon in temperate perennial grasslands. It occurs in a nonrandom fashion and is usually explained by increased competitive size asymmetry between the co-occurring winner (tall species with optima in productive habitats) and loser species (small-statured plants typical for unproductive habitats). It remains unclear why nutrient addition decreases diversity in communities consisting of losers only, whereas it has little effect on winner-only communities.Here, I used the framework of modern coexistence theory to explore fertilization-driven changes in fitness and niche differences between different combinations of field-identified winner (W) and loser (L) species. I experimentally estimated competition parameters for plant species pairs constructed from a pool of eight species, including pairs of species from the same (WW, LL) and different species categories (LW) grown for approximately 2 years in control and fertilized conditions. Concurrently, I also followed plant species diversity in mesocosm communities constructed from the same species pool (four-species communities including winners, losers, or both) exposed to control and nutrient addition. I found that nutrient addition can reduce but, unexpectedly, also promote species coexistence depending on the type of species pairs. Whereas nutrient addition eroded the coexistence of losers with winners, but also with other losers, treatment had the opposite effect on the persistence of winner species. Fertilization induced large fitness differences between species in loser-winner and loser-loser combinations, but had little effect on the fitness differences of species within the winner-winner combination. In addition, the persistence of winner pairs was promoted by larger niche differences compared to loser species, irrespective of soil nutrients. The differences in how nutrient addition modified coexistence at the pairwise level were reflected by differences in the evenness of multispecies communities assembled from the corresponding species categories. These results suggest that the effect of eutrophication on plant species richness cannot simply be explained by an increased competitive asymmetry. To fully understand the effect of fertilization on the diversity of temperate grasslands, interspecific and intraspecific

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Assessing the roles of nitrogen, biomass, and niche dimensionality as drivers of species loss in grassland communities

Cited by 37 publications

References 201 publications

Species existence and coexistence under nutrient enrichment in the Park Grass

Species existence and coexistence under nutrient enrichment in the Park Grass

A single application of fertilizer can affect semi-natural grassland vegetation over half a century

Fitness and niche differences are both important in explaining responses of plant diversity to nutrient addition

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