Impacts of nitrogen addition on plant biodiversity in mountain grasslands depend on dose, application duration and climate: a systematic review

Humbert, Jean‐Yves; Dwyer, John M.; Andrey, Aline; Arlettaz, Raphaël

doi:10.1111/gcb.12986

Cited by 176 publications

(156 citation statements)

References 99 publications

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“…; Humbert et al . ). Instead, we found that productivity had little effect on recruitment in any of our focal species, potentially suggesting that productivity gradients in this experiment were not large enough to induce strong differences in competition.…”

Section: Discussionmentioning

confidence: 97%

Separating sources of density‐dependent and density‐independent establishment limitation in invading species

et al. 2016

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Summary Successful colonization by invasive species depends on both the ability to disperse seeds to a site and an ability to establish once seeds have arrived. While seed and establishment limitation are known to jointly influence colonization, decomposing establishment limitation into density‐dependent and density‐independent components has remained challenging. Here, we couple theoretical models of recruitment with a multispecies invasion experiment conducted within a natural gradient of soil moisture and productivity to assess how variation in establishment limitation shapes outcomes for invasion. Recruitment was affected by both density‐dependent and density‐independent sources of establishment limitation in three of four species. Soil moisture stress and productivity both increased density‐independent mortality in one species, whereas density‐dependent mortality increased in locations with favourable soil moisture. Synthesis. Successful establishment of invading species can be limited by both density‐dependent and density‐independent mechanisms. In particular, the strength of density‐independent limitation may depend on natural gradients in abiotic factors. The varying strengths of establishment limitation suggest that patterns of invasion are likely to be uneven both in space and in time. Understanding how intraspecific competitive constraints and density‐independent limitation vary with abiotic gradients can assist with predicting when invasions are likely to occur, information that can be harnessed in the development of better methods for control.

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Section: Discussionmentioning

confidence: 97%

Separating sources of density‐dependent and density‐independent establishment limitation in invading species

et al. 2016

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“…Also, we cannot exclude effects from high N deposition, which might additionally have influenced this trend (Humbert et al. ).…”

Section: Discussionmentioning

confidence: 99%

Recent changes in alpine vegetation differ among plant communities

Gritsch

Dirnböck

Dullinger

2016

J Vegetation Science

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Aim Reports on recent changes in high‐mountain vegetation are mostly based on re‐surveys of mountaintop floras. Summits are very specific habitats, however, and detected trends may not necessarily represent alpine vegetation in general. Here, we analyse re‐samples of three prevalent plant communities in non‐summit alpine habitats (snowbeds, two grassland types). Location Northeastern European Alps. Methods In 2013 we re‐sampled a total of 91 relevés of three plant communities from the 1990s. We compared original and re‐samples in terms of species richness (α‐diversity), pair‐wise compositional dissimilarity (β‐diversity) and species pool size (γ‐diversity). Moreover, we calculated mean ecological indicator values (temperature, moisture, nutrient status and soil acidity) as well as potential plant height for each of the 182 relevés. Differences in species pool sizes between the two sampling campaigns were evaluated by randomization tests based on rarefaction curves. In all other cases, differences were compared using paired t‐tests or Kruskal–Wallis tests. Results Of all the community attributes analysed, changes were most consistent with respect to increasing mean species' temperature indicator values. Mean potential plant height also increased slightly in all three communities, but differences were statistically significant only in the case of Carex sempervirens grasslands. Changes in species richness varied among communities, with only the Carex firma grasslands accumulating significantly more species at both the local and regional scales. For the other two plant communities, α‐ and γ‐diversity remained constant, but β‐diversity increased. Indicator values other than temperature either did not change or changed idiosyncratically in the different communities. Conclusions Our results indicate that some long‐term changes occurred in high mountain grassland and snowbed vegetation of the study area. Consistent changes in mean species' temperature indicator values suggest that climate warming was an important driver. However, trends in biodiversity metrics differed substantially between the studied communities. We conclude that recent increase in species numbers commonly reported from temperate and boreal mountaintops cannot readily be generalized to all temperate and boreal high‐mountain vegetation.

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“…In a narrow focus, supplementing soils depleted in phosphorus would be a reasonable response to ensure high levels of livestock production in depleted Tibetan rangeland. It is the case that fertilization in semi-natural grassland with inorganic P can significantly increase plant biomass production, but only at the cost of rapid loss of species diversity (Humbert et al, 2015;Stevens et al, 2015); properly managed removal of aboveground biomass by grazing can rescue part of the biodiversity loss (Yang et al, 2012;Borer et al, 2014). Organic fertilizers (Bi et al, 2009;Diacono and Montemurro, 2010) or the use of phosphate solubilizing microorganisms (Khan et al, 2009) provide similar alternatives.…”

Section: Is There Evidence For Phosphorus Depletion In Tibetan Rangelmentioning

confidence: 99%

Tradeoffs between forage quality and soil fertility: Lessons from Himalayan rangelands

Niu

Zhang

et al. 2016

Agriculture, Ecosystems & Environment

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A B S T R A C TPastoralists on Eurasian rangeland often believe that traditional management practices involving moderate rotational grazing ensure sustainable yield, increase plant digestibility and promote biodiversity. To assess the generality of these suppositions we compared biomass production, community leaf C, N and P stoichiometry, leaf trait diversity and carbon and nutrient pools in root and soil for moderately grazed vs. ungrazed plots in Tibetan alpine meadows. We used five leaf traits (leaf C, leaf N and leaf P concentrations; SLA: specific leaf area, and LDMC: leaf dry matter content) as indicators of plant digestibility and rangeland quality. We measured these foliar traits and the ramet numbers for component species in moderately grazed plots as well as in exclosures (3-11 years) at five sites across the Qinghai-Tibetan plateau. Community weighted mean (CWM) trait values and functional dispersion (FDis) were used to quantify the mean and the variance in the distribution of trait values, respectively. Both the leaf P CWM and leaf P FDis generally increased under grazing and the LDMC CWM decreased, leading to improved plant digestibility and rangeland quality (e.g. high, community-wide leaf nutrients). The leaf C CWM , leaf N CWM and SLA CWM increased under grazing but the FDis of these traits tended to decrease. Grazing generally increased species diversity but decreased aboveground biomass, organic carbon, and nutrient concentrations in soil and root, especially decreasing root nitrogen and soil available phosphorus. Both root biomass and the leaf C:N CWM decreased in grazed plots at wet sites, but increased at dry sites. The community-wide increase and greater interspecific diversity in leaf nutrient concentrations coupled with decreasing LDMC CWM show that grazing induced an increase in plant digestibility, nutrient concentrations, and nutrient diversity in these alpine meadows. However, this increase in forage quality comes at the cost of losses in both carbon stock and nutrient availability that depress biomass production. Our findings and a review of related literature suggest that traditional grazing practices involve a trade-off between short-term yield and sustainability, a management challenge that must be addressed on rangelands with low soil fertility.

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Impacts of nitrogen addition on plant biodiversity in mountain grasslands depend on dose, application duration and climate: a systematic review

Cited by 176 publications

References 99 publications

Separating sources of density‐dependent and density‐independent establishment limitation in invading species

Separating sources of density‐dependent and density‐independent establishment limitation in invading species

Recent changes in alpine vegetation differ among plant communities

Tradeoffs between forage quality and soil fertility: Lessons from Himalayan rangelands

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