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<table><caption>Table 1. Relationships of organismic growth rate (GR) with the increase in the N:P ratio.</caption><thead><tr><th>Ecosystem</th><th>Study type</th><th>Main results</th><th>Reference</th></tr></thead><tbody><tr><td></td><td>Microcosm</td><td>↓ GR (when nutrients are not limiting)</td><td>Bi et al., 2012</td></tr><tr><td></td><td>Metadata review</td><td>↓ GR</td><td>Loladze and Elser, 2011</td></tr><tr><td rowspan="2">Lakes</td><td>Field</td><td>↓ GR</td><td>Naddafi et al. 2012</td></tr><tr><td>Mesocosm</td><td>↓ GR</td><td>Stahl-Delbanco et al. 2003</td></tr><tr><td>Lake</td><td>Field</td><td>↓ GR (when nutrients are not limiting)</td><td>Tanner et al. 2011</td></tr><tr><td></td><td>Microcosm</td><td>No conclusive relationships</td><td>Guo et al., 2018</td></tr><tr><td>Freshwater ecosystems</td><td>Field</td><td>↓ GR</td><td>Arbaciauskas et al., 2013</td></tr><tr><td rowspan="3">Coastal waters</td><td>Mesocosm</td><td>↓ GR</td><td>Prado et al., 2014</td></tr><tr><td>Review</td><td>↓ GR in phytoplankton</td><td>Hillebrand et al., 2013</td></tr><tr><td>Microcosm</td><td>No conclusive relationships</td><td>Trommer et al., 2012</td></tr><tr><td rowspan="2">Coastal waters</td><td>Field</td><td>Unimodal GR response to P</td><td>Reef et al., 2012</td></tr><tr><td>Microcosm</td><td>↓ GR</td><td>Rivas-Ubach et al., 2018</td></tr><tr><td rowspan="2">Stream</td><td>Field</td><td>↓ GR</td><td>Bumpers et al., 2015</td></tr><tr><td>Mesocosm</td><td>↓ GR</td><td>Prado et al., 2014</td></tr><tr><td>Southeastern Pacific</td><td>Field</td><td>↓ GR</td><td>Franz et al., 2012</td></tr><tr><td rowspan="2">Freshwater</td><td>Mesocosm</td><td>↓ GR</td><td>Molazadeh et al., 2019</td></tr><tr><td>Common garden</td><td>↓ GR</td><td>Wanek and Zotz, 2011</td></tr><tr><td rowspan="2">Panama</td><td>Field and common garden</td><td>↓ GR</td><td>Peng et al., 2011</td></tr><tr><td>Common garden</td><td>↓ GR (when nutrients are not limiting)</td><td>Wanek and Zotz, 2011</td></tr><tr><td>Mediterranean grassland</td><td>Field</td><td>↓ GR</td><td>Rivas-Ubach et al., 2012</td></tr><tr><td></td><td>Pot experiment</td><td>↓ GR</td><td>Liang et al., 2018</td></tr><tr><td>Scrubland</td><td>Field</td><td>↓ GR</td><td>He et al., 2017</td></tr><tr><td>Temperate forest</td><td>Field</td><td>↓ GR</td><td>Wang et al., 2013</td></tr></tbody></table>
<table><tr><td>Crops (Triticum aestivum, Hordeum vulgare and Zea mays)</td><td></td><td>↓GR in initial growth stages<br/>↑ GR in advanced growth stages</td><td>Zhang et al., 2019 (submitted)</td></tr><tr><td>Juniperus przewalskii, China</td><td>Field</td><td>GR ↓</td><td>Wang et al. 2019c</td></tr><tr><td rowspan="2">Shrubland</td><td>Field</td><td>Unimodal relationships with GR</td><td>Yu et al., 2012</td></tr><tr><td>Pot experiment</td><td>↓ GR</td><td>Yan et al., 2013</td></tr><tr><td></td><td>Greenhouse experiment</td><td>↑ GR</td><td>Niu et al., 2019</td></tr><tr><td>Freshwater ecosystems (parasitic species)</td><td>Field</td><td>GR ↓</td><td>Paseka and Grunberg 2018</td></tr><tr><td>Macroinvertebrates of streams</td><td>Field</td><td>GR ↓</td><td>Demi et al. 2018</td></tr><tr><td>Zooplankton of western Pacific</td><td>Field</td><td>GR ↓</td><td>Chen et al. 2018b</td></tr></table>
<table><caption>Table 2. Results of studies testing the relationships between differences in species elemental composition and taxonomy/phylogeny distance.</caption><thead><tr><td>Species and/or ecosystem</td><td>Study type</td><td>Main results (+, significant phylogenetic signal or taxonomic determinism; -, no significant phylogenetic signal or taxonomic determinism)</td><td>Reference</td></tr></thead><tbody><tr><td>Main forest tree species of Catalonia</td><td>Field</td><td>+</td><td>Sardans and Peñuelas 2014</td></tr><tr><td>Main forest tree species of Europe</td><td>Field</td><td>+</td><td>Sardans et al. 2015</td></tr><tr><td>Main forest tree species of Spain</td><td>Field</td><td>+</td><td>Sardans et al. 2016</td></tr><tr><td>98 Mediterranean woody species</td><td>Field</td><td>+</td><td>De la Riva et al. 2017</td></tr><tr><td>Dominant plant species in Sonoran Desert</td><td>Field</td><td>+</td><td>Castellanos et al. 2018</td></tr><tr><td>Natural gradients in coastal herbaceous wetlands</td><td>Field</td><td>+</td><td>Hu et al 2018</td></tr><tr><td>Plants along natural gradient (Norway)</td><td>Field</td><td>+</td><td>Reimann et al. 2018</td></tr><tr><td>Root elemental composition of 281 species in Chinese forests</td><td>Field</td><td>+</td><td>Zhao et al. 2018</td></tr><tr><td>702 plant species</td><td>Review</td><td>+</td><td>Zhang et al. 2012</td></tr><tr><td>Benthic organisms</td><td>Field</td><td>+</td><td>Lovelock et al. 2014</td></tr><tr><td>48 species of Artemisia from 65 sites across northern China</td><td>Field</td><td>+</td><td>Yang et al. 2015</td></tr><tr><td>348 plant species in Chinese forests</td><td>Review</td><td>+</td><td>Wu et al. 2017</td></tr><tr><td>32 Ericaceae species (China)</td><td>Field</td><td>+</td><td>Zhang et al. 2019</td></tr><tr><td>30 sites containing four Tamarix species</td><td>Field</td><td>-</td><td>Sun et al. 2017</td></tr><tr><td>Marine phytoplankton</td><td>Mesocosm</td><td>-</td><td>Garcia et al. 2018</td></tr><tr><td>Aquatic heterotrophic bacteria</td><td>Mesocosm</td><td>+</td><td>Godwin and Cotner 2018</td></tr><tr><td>Fynbos vegetation</td><td>Field</td><td>+</td><td>Verboom et al. 2017</td></tr><tr><td>Microalgae</td><td>Review</td><td>+</td><td>Finkel et al. 2016</td></tr><tr><td>Fungi and bacteria in leaf litter</td><td>Field</td><td>+</td><td>Mouginot et al. 2014</td></tr></tbody></table>
<table><tr><td>Marine proteobacteria</td><td>Mesocosm</td><td>-</td><td>Zimmerman et al. 2014</td></tr><tr><td>China grassland plant communities</td><td>Field</td><td>+</td><td>Song et al. 2014</td></tr><tr><td>564 Mediterranean plant species</td><td>Review</td><td>+</td><td>Stock and Verboom 2012</td></tr><tr><td>Animals of Atacama Desert (Chile)</td><td>Field</td><td>+</td><td>Gonzalez et al. 2011</td></tr><tr><td>Rainforest tree species</td><td>Field</td><td>-</td><td>Bai et al. 2019</td></tr><tr><td>203 plant species of a Tibetan meadow</td><td>Field</td><td>+</td><td>Bu et al. 2018</td></tr><tr><td>Woody plants, altitudinal gradient (China)</td><td>Filed</td><td>+</td><td>Yang et al. 2017a</td></tr><tr><td>Different trophic groups</td><td>Review</td><td>+</td><td>Gonzalez et al. 2017</td></tr><tr><td>Plants along large-scale gradient</td><td>Field</td><td>+</td><td>Yang et al. 2017b</td></tr><tr><td>163 shrubland species (China)</td><td>Field</td><td>+</td><td>Yang et al. 2016</td></tr><tr><td>177 plant species in a Karst area (China)</td><td>Field</td><td>+</td><td>Hao et al. 2014</td></tr><tr><td>Inner Mongolian plants</td><td>Field</td><td>+</td><td>Liu et al. 2013</td></tr><tr><td>108 plant species from saline environments in Iran</td><td>Field</td><td>+</td><td>Matinzadeh et al. 2019</td></tr><tr><td>Chihuahuan Desert gypsophilic plants</td><td>Field</td><td>+</td><td>Muller et al. 2017</td></tr><tr><td>Peat mosses</td><td>Field</td><td>-</td><td>Limpens et al. 2017</td></tr><tr><td>670 plant species</td><td>Review</td><td>+</td><td>Watanable et al. 2007</td></tr><tr><td>167 plant species (China)</td><td>Field</td><td>+</td><td>Zhang et al. 2018</td></tr><tr><td>564 plant species from five Mediterranean climatic regions</td><td>Review</td><td>+</td><td>Kerkhoff et al. 2006</td></tr><tr><td>87 species from a tropical dry forest in Costa Rica</td><td>Field</td><td>+</td><td>Powers and Tiffin 2010</td></tr><tr><td>71 macroinvertebrate species</td><td>Field</td><td>+</td><td>Gonzalez et al. 2018</td></tr><tr><td>Lake communities of different trophic levels</td><td>Field</td><td>+</td><td>Bartrons et al. 2018</td></tr><tr><td>Phytoplankton</td><td>Review</td><td>+</td><td>Quigg et al. 2011</td></tr><tr><td>213 species at 199 research sites in the grassland biomes of China</td><td>Field</td><td>+</td><td>He et al. 2008</td></tr><tr><td>48324 vascular plant species (review)</td><td>Field</td><td>+</td><td>Cornwell et al. 2014</td></tr><tr><td>508 Amazonian trees</td><td>Field</td><td>+</td><td>Fyllas et al. (2009)</td></tr><tr><td>334 angiosperm species</td><td>Greenhouse experiments</td><td>+</td><td>Neugebauer et al. 2018</td></tr><tr><td>27 desert herbs</td><td>Field</td><td>+</td><td>He et al. (2016)</td></tr></table>
<table><tr><td>25 plant species from Brazil</td><td>Field</td><td>+</td><td>Viani et al. (2014)</td></tr></table>

Box 1. Classical paradigms of ecological stoichiometry and the main new challenges.

Classical Paradigms and new challenges

<table><thead><tr><td>Classical paradigms</td><td>Some new challenges</td></tr></thead><tbody><tr><td><strong>GRH</strong><br>Growth rate capacity at cell level<br>depends of the N:P ratio<br>as proxy of protein:RNA ratio.<br>Increased growth rate is favoured<br>by an increase in P-rich RNA (low N:P ratio)<br>under non-limiting N and P conditions</td><td>Are environmental N:P ratios also related to the structure and functions of other ecosystems (terrestrial and marine)?</td></tr><tr><td><strong>Plankton community structure</strong><br>in freshwater ecosystems is related<br>to water N and P concentrations<br>and N:P ratio</td><td>Can we gain more sensitivity and success by relating the elemental composition of medium (soil and water) and community to ecosystem structure, functions, and diversity using elements other than C, N, and P (for example, K, Mg, S, Ca, etc.)?</td></tr><tr><td><strong>Redfield ratio</strong><br>Ocean phytoplankton<br>C:N:P (100:16:1 on average)</td><td>How do the main drivers of global change affect the relation between ecosystem stoichiometry and ecosystem functionality, composition, and diversity?</td></tr><tr><td></td><td>Do components of homeostasis and flexibility/plasticity of stoichiometry exist among the main bio-elements across different taxa and environmental gradients</td></tr><tr><td></td><td>How do shifts in ecosystem stoichiometry (for instance, in response to global change) impact human health and wellness?</td></tr></tbody></table>
Figure captions

Figure 1. Terrestrial plant N:P ratios and growth rates have been correlated during the initial stages of life when most N and P are allocated to growth but not during advanced stages of growth when the allocation of N and P to organs and functions not directly involved in growth increases exponentially.

Figure 2. Stress-tolerant plants have been associated with high N:P ratios and a more homeostatic stoichiometry, fast-growing ruderal species have been associated with low N:P ratios, and competitor species, with N:P ratios between that of stress-tolerant and ruderal species.

Figure 3. General results of shifts in N:P ratios in plant/soil systems in field drought manipulation experiments and along aridity gradients.

Figure 4. New achievements and open scenarios of ecological stoichiometric studies in the last years.
<figure><img src="image_3.png" /><figcaption>Figure 1</figcaption></figure>
<figure><img src="image_4.png" /><figcaption>Figure 2</figcaption></figure>
<figure><img src="image_5.png" /><figcaption>Figure 3</figcaption></figure>
<figure><img src="image_6.png" /><figcaption>Figure 4</figcaption></figure>