Calcium plus magnesium indicates digestibility: the significance of the second major axis of plant chemical variation for ecological processes

Mládková, Pavla; Mládek, Jan; Hejduk, Stanislav; Hejcman, Michal; Pakeman, Robin J.

doi:10.1111/ele.12956

Cited by 38 publications

(38 citation statements)

References 60 publications

(87 reference statements)

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“…Interestingly, in our experiment, we found that nutrient contents (N and Ca) were about twice as important as structural components (LDMC and fibres) in determining litter quality (combined path coefficients of 0.61 for nutrients and -0.36 for structure). Effects of N have been shown in many studies (Garnier et al, 2004;Cornwell et al, 2008) and as pointed out in Mládková, Mládek, Hejduk, Hejcman, and Pakeman (2018), Ca and Mg content (which were highly correlated in our case) also indicate a better digestibility and a higher decomposability of the litter (García-Palacios et al, 2016a). Ca and Mg are key components of invertebrate diets and can therefore increase their abundance (National Research Council, 2005), which may explain their positive effects on decomposition.…”

Section: Functional Composition Is the Main Driver Of Litter Qualitysupporting

confidence: 77%

Decomposition disentangled: A test of the multiple mechanisms by which nitrogen enrichment alters litter decomposition

et al. 2020

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1. Nitrogen (N) enrichment has direct effects on ecosystem functioning by altering soil abiotic conditions and indirect effects by reducing plant diversity and shifting plant functional composition from dominance by slow to fast growing species. Litter decomposition is a key ecosystem function and is affected by N enrichment either by a change in litter quality (the recalcitrance of the plant material) or through a change in soil quality (the abiotic and biotic components of the soil that affect decomposition). The relative importance of soil and litter quality and how the direct and effects of N alter them remains poorly known. 2. We designed a large grassland field experiment manipulating N enrichment, plant species richness and functional composition in a full factorial design. We used three complementary litter bag experiments and a novel structural equation modelling approach to quantify the relative effects of the treatments on litter and soil quality and their importance for total decomposition. 3. Our results indicate that total decomposition was mostly driven by changes in litter quality rather than soil quality. Litter quality was affected by the nutrient contents (N and calcium) and structural components of the litter (leaf dry matter content, fibres). N enrichment increased litter decomposition mostly indirectly through a shift in functional composition toward faster growing plant species producing higher quality litter. N enrichment also had effects on soil, by directly and indirectly affected vegetation cover, but this had relatively few consequences for the total decomposition rate. 4. Synthesis. Our approach provides a mechanistic tool to test the drivers of litter decomposition across different ecosystems. Our results show that functional composition is more important than richness or soil quality in determining litter decomposition and that N enrichment effects mainly occur via above-rather than belowground processes. This highlights the importance of considering shifts in plant species composition when assessing the effects of N enrichment 52 on decomposition. 53. CC-BY-NC-ND 4.0 International license It is made available under a (which was not peer-reviewed) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity.

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Section: Functional Composition Is the Main Driver Of Litter Qualitysupporting

confidence: 77%

Decomposition disentangled: A test of the multiple mechanisms by which nitrogen enrichment alters litter decomposition

et al. 2020

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“…Considering the known link of these traits with the decomposable litter fraction, the strong effect of invader-induced changes in these traits on litter decomposition in our study, is thus hardly surprising (Makkonen et al, 2012;Mládková et al, 2018). Previous research in our study system has furthermore indicated that the shifts in the community trait composition are largely effectuated through intraspecific trait changes induced by competition with the invader, rather than through species composition changes (Helsen, Van Cleemput, Bassi, Graae, et al, 2020).…”

Section: Invader Impact On Litter Decompositionsupporting

confidence: 44%

“…Plant height (cm) and leaf area (mm 2 ) are proxies for the second axis of the global spectrum of plant form and function ('size of whole plants and their parts'), which relates to competitive ability (Díaz et al, 2016). Leaf mass per area (LMA, g/cm 2 ), leaf dry matter content (LDMC, mg/g) and leaf nitrogen (N), phosphorous (P) and potassium content (K; mg/mm 2 ) are related to the leaf economics spectrum (Cornelissen & Thompson, 1997;Cornwell et al, 2008) and leaf magnesium (Mg) and calcium content (Ca; mg/ mm 2 ) relate more directly to labile litter fraction components, such as pectin and chlorophyll units (Makkonen et al, 2012;Mládková et al, 2018). Note that all leaf nutrients were expressed on area basis, rather than mass basis to enhance comparability with the retrieved optical traits.…”

Section: Functional Traitsmentioning

confidence: 99%

“…Here, we collected both plot-level species-specific functional (leaf) traits and leaf hyperspectral reflectance across 25 R. rugosa invaded and 25 uninvaded dune vegetation plots along the Belgian North sea coast. The selected traits covered three independent trait variation axes that have previously been related to litter decomposition, namely the leaf economics spectrum (Cornwell et al, 2008;de la Riva, Prieto, & Villar, 2019;Díaz et al, 2016;Wright et al, 2004), additional leaf structural (labile litter fraction-related) components (Makkonen et al, 2012;Mládková, Mládek, Hejduk, Hejcman, & Pakeman, 2018) and the size of whole plants and their parts (Díaz et al, 2016). Some optical traits were quantified through PROSPECT-D inversion (Féret, Gitelson, Noble, & Jacquemoud, 2017) (Bruun, 2005;Kollmann, Jørgensen, Roelsgaard, & Skov-Petersen, 2009).…”

Section: Introductionmentioning

confidence: 99%

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Optical traits perform equally well as directly‐measured functional traits in explaining the impact of an invasive plant on litter decomposition

et al. 2020

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Functional traits can help elucidate and predict the impact of invasive plant species on ecosystem functioning. Yet, this approach requires comprehensive and labour‐intensive trait collection campaigns, covering intraspecific trait variation of both the invader and native species in the invaded community. One potential way to overcome these logistic constraints is using hyperspectral remote sensing technology to efficiently quantify functional trait values. Although such spectrally derived or ‘optical’ traits are known to closely link to directly measured functional traits, little research has explored how well these optical traits perform in assessing invader‐induced ecosystem impact. Here, we explored the trait‐mediated impact of the invasive Rosa rugosa on litter decomposition and evaluated whether optical traits perform equally well as directly measured traits in predicting litter decomposition variation. We collected data on species‐specific functional traits, leaf hyperspectral reflectance and standardized ‘tea bag index’ litter decomposition across 25 invaded and 25 uninvaded coastal grassland plots. The selected traits were all potentially related to litter decomposition and covered the leaf economics spectrum, additional leaf structural components and competitive ability. Optical traits were quantified through a combination of a physical radiative transfer model inversion and vegetation indices calculations. Invasion significantly increased the stabilization factor, i.e. the amount of resulting recalcitrant litter. Invader impact on litter decomposition could be entirely explained by changes it induced in the functional traits of the native community, rather than by the invader's traits itself. More specifically, the invader pushed the invaded community towards traits associated with high litter quality. Optical traits performed equally well as directly measured traits in explaining the invasion impact on the stabilization factor (R2 = 41.9% vs. 38.5%). Furthermore, the interpretation of the results based on optical traits resulted in a similar functional understanding of the invader impact. Synthesis. Our results indicate the potential of hyperspectral data to explain changes in ecosystem functioning. The combination of radiative transfer models and vegetation indices allowed to extract all relevant trait information from the hyperspectral data. This framework thus presents a practical shortcut to assess relevant leaf traits, requiring only a limited amount of field trait measurements.

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“…Finally, it was interesting to see the potential importance of Ca and Mg in explaining the variation in nutrient dynamics in both fine root and twigs. This reflects the important role of these elements in decomposition [35,36].…”

Section: Initial Chemistry and Nutrients Dynamics During Decompositionmentioning

confidence: 83%

Fine Roots of <em>Parashorea chinensis</em> Decompose Slower than Twigs

Dossa¹,

Jin²,

Lü³

et al. 2019

Preprint

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Plants produce above- and below-ground biomass. However, our understanding of both production and decomposition of below-ground biomass is poor, largely because of the difficulties of accessing study materials. Below-ground organic matter decomposition studies are scanty and especially rare in the tropics. Here, we used a litter bag experiment to quantify the mass loss and nutrients dynamics of decomposing twigs and fine roots from an arbuscular mycorrhizal fungal associated tree, Parashorea chinensis, in a tropical rain forest in Southwest China. Overall, twig litter decomposed 1.9 times faster than fine roots (decay rate (k) twig=0.255, root=0.134). The difference in decomposition rates can be explained by a difference in phosphorus (P) concentration, availability and use by decomposers or C quality. Both materials showed an increase in N concentration, with final measurements still higher than initial levels. This suggests N may not be available due to microbial immobilization. Both carbon and nitrogen dynamics were significantly predicted by mass loss and showed a negative and positive relationship, respectively. Our study results imply that fine roots carbon and nitrogen contribute more to soils organic matter and enlarge the resident time. Therefore, better understanding of carbon cycle requires better understanding of mechanisms governing below ground biomass decomposition.   

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Calcium plus magnesium indicates digestibility: the significance of the second major axis of plant chemical variation for ecological processes

Cited by 38 publications

References 60 publications

Decomposition disentangled: A test of the multiple mechanisms by which nitrogen enrichment alters litter decomposition

Decomposition disentangled: A test of the multiple mechanisms by which nitrogen enrichment alters litter decomposition

Optical traits perform equally well as directly‐measured functional traits in explaining the impact of an invasive plant on litter decomposition

Fine Roots of <em>Parashorea chinensis</em> Decompose Slower than Twigs

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