Ojos que no ven... ¿Qué podemos hacer para incluir más a la fracción subterránea en estudios de vegetación?

Mársico, Luis López; Pestoni, Sofía; Conti, Georgina; Pérez‐Harguindeguy, Natalia; Pastur, Guillermo Martínez; Pinto, Priscila; Sarquis, Agustín; Reyes, María Fernanda; Peri, Pablo Luís; Piñeiro, Gervasio

doi:10.25260/ea.20.30.2.0.965

Cited by 7 publications

(4 citation statements)

References 14 publications

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“…Our study evaluated not only the total and specific above‐ground responses of a perennial‐grass‐dominated patches in an arid community but also its total and specific below‐ground biomass, an aspect that has been left out because of the methodological difficulties involved (Lauenroth, 2000; Wilson, 2014; Reyes & Aguiar, 2017a, 2021; López‐Mársico et al, 2020). The overrepresentation of pot experiments (Schmidt et al, 1997a, 1997b; Bleier & Jackson, 2007) compared to field experiments underscores the importance and strength of our plot experiment, performed in the field without manipulating the species present (including wild animals but excluding domestic sheep).…”

Section: Discussionmentioning

confidence: 99%

Arid community responses to nitrogen and carbon addition depend on dominant species traits and are decoupled between above‐ and below‐ground biomass

Campana

Reyes

Aguiar

2022

J Vegetation Science

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Questions Arid communities are strongly limited by soil resources including water and nitrogen (N). Plants compete for N with other plants and microorganisms, which are also limited by carbon (C). We propose that above‐ and below‐ground plant responses to soil resources are modulated by community structure (species relative abundances, “mass ratio hypothesis”) and species traits (relative growth rates — RGRs). We evaluated the single and combined effects of soil N and C addition on the above‐ and below‐ground biomass accumulation of perennial grass patches in an arid community, and the mechanisms involved in their responses. Location Patagonian steppe, Argentina. Methods We added N (2 g N m−2; NH4NO3) and C (330 g C m−2; sucrose) to 1‐m2 field plots in a factorial design. After two years, we harvested above‐ground (n = 5 plots) and below‐ground biomass (n = 10 soil cores) and sorted it by species. We measured potential soil respiration as a proxy of microbial activity. Results Total above‐ground biomass increased by 55% as a result of N and decreased by 45% as a result of C addition, in relation to controls. C addition reduced total below‐ground biomass by 42%. The above‐ground differences were associated with changes in the biomass of dominant species according to their RGRs. Poa ligularis (dominant, high RGR) increased by 92% as a result of N addition while Pappostipa speciosa (dominant, low RGR) decreased by 55% as a result of C addition. Intermediate and subordinate grasses did not modify their biomass, independently of their RGR. Potential soil respiration was three times higher in plots with C addition than in control plots. Conclusions Community biomass was explained by a combination of mass ratio hypothesis and specific RGR, as dominant grasses controlled above‐ground community responses to N (high‐RGR species) and C addition (low‐RGR species). Our findings highlight the independence between the above‐ and below‐ground processes and the importance of considering community equitability and species characteristics to predict plant community responses to changes in soil resources.

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Section: Discussionmentioning

confidence: 99%

Arid community responses to nitrogen and carbon addition depend on dominant species traits and are decoupled between above‐ and below‐ground biomass

Campana

Reyes

Aguiar

2022

J Vegetation Science

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“…Currently, there is a trend to incorporate the below‐ground compartment in ecological studies in terms of specific biomass (López‐Mársico et al . 2020). The identification and quantification of root biomass allow estimating the territoriality magnitude of species (Schenk 2006) and the soil volume explored by each species.…”

Section: Introductionmentioning

confidence: 99%

Do xerophytic and mesophytic perennial grasses differ in soil resource capture and allocation? A field ¹⁵N experiment

Reyes

Aguiar

2021

Austral Ecology

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In rangelands, pattern and processes below‐ground are important for a complete understanding of their ecology. Recent studies in grass‐dominated communities in Europe, North America and South America indicate that root systems of several species may overlap their root systems. This may indicate that, in these communities, resource acquisition and allocation strategies could play a relevant role in community assemblage. Resources absorption and allocation may be related to ecological strategies relevant in an arid steppe. Here, we explore if coexisting xerophytic and mesophytic perennial grasses differ in resource absorption and allocation to below‐ and above‐ground portions. We conducted a field labelling experiment to trace 15N (nitrogen) to compare acquisition and relative below‐ and above‐ground nitrogen allocation among four perennial grass species. We worked with two mesophytic (fast‐growing) and two xerophytic (slow‐growing) species. Our hypothesis was that mesophytic species will allocate greater proportions of N and produce a higher amount of biomass than xerophytic species. The four species showed similar 15N concentration, which changed over time in roots, while it remained constant in leaves. On average, all species presented 0.9% 15N atom excess in roots and 1.1% in green leaves. Mesophytic species showed higher reproductive over total tiller ratio than xerophytic species. Bromus pictus reached 60% while Poa ligularis only 20%. In xerophytic species (Pappostipa speciosa and Pappostipa humilis), this ratio was close to 0%. Despite their differences in growth rates, these mesophytic and xerophytic grass species do not differ in the estimated nitrogen acquisition. Nevertheless, there are ecological trade‐offs between allocating resources to above‐ground leaf biomass and reproductive tillers which could be related to species organisation in the community.

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“…Such difference may affect both carbon gains and stocks. Although in the last decades, there has been an exponential increase in the number of studies that consider the below-ground plant portion in grasslands of southern South America (López-Mársico et al, 2020), the information that has been generated is sparsely included in studies with global data. In order to facilitate future inclusions in global analyses, we collect and synthesize regional data.…”

Section: Introductionmentioning

confidence: 99%

Grazing exclusion reduces below‐ground biomass of temperate subhumid grasslands of South America: A meta‐analysis and a database

et al. 2023

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There are several plant below‐ground biomass databases for grasslands, but the contribution from the southern hemisphere is minimal. Particularly, no study has compiled the published values of plant below‐ground biomass for the temperate subhumid grasslands of South America. In these grasslands, called Río de la Plata grasslands, grazing is the most frequent disturbance. We set two objectives: (1) to compile and synthesize data of four variables: below‐ground biomass, fraction of total biomass allocated below‐ground, below‐ground net primary productivity and below‐ground biomass turnover rate; (2) to estimate the effect of grazing exclusion on below‐ground biomass by means of a meta‐analysis. There are 15 studies published on six out of eight regional sub‐divisions of the Río de la Plata grasslands. The most evaluated variable was below‐ground biomass, followed by below‐ground net primary productivity, while the other two variables were scarcely registered. Below‐ground biomass in the shallow portion of the soil (0–10 cm) was on average 877 g m−2. Below‐ground net primary productivity resulted in an average of 245 g m−2 year−1 (estimated using the ingrowth core method) or 560 g m−2 year−1 (core method). The fraction of total biomass allocated below‐ground was on average 0.75. Below‐ground biomass turnover rate presented an average of 2.5 years. On average, the effect of grazing exclusion on below‐ground biomass depended on exclusion time. When exclusion time was shorter than or equal to 3 years, grazing exclusion did not affect below‐ground biomass. In contrast, when exclusion time was longer than 3 years, grazing exclusion reduced below‐ground biomass by 62% (0–10 cm depth) and by 40% (total depth). Excluding South American grasslands from the global databases may introduce some biases in the observed patterns.

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Ojos que no ven... ¿Qué podemos hacer para incluir más a la fracción subterránea en estudios de vegetación?

Cited by 7 publications

References 14 publications

Arid community responses to nitrogen and carbon addition depend on dominant species traits and are decoupled between above‐ and below‐ground biomass

Arid community responses to nitrogen and carbon addition depend on dominant species traits and are decoupled between above‐ and below‐ground biomass

Do xerophytic and mesophytic perennial grasses differ in soil resource capture and allocation? A field ¹⁵N experiment

Grazing exclusion reduces below‐ground biomass of temperate subhumid grasslands of South America: A meta‐analysis and a database

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Ojos que no ven... ¿Qué podemos hacer para incluir más a la fracción subterránea en estudios de vegetación?

Cited by 7 publications

References 14 publications

Arid community responses to nitrogen and carbon addition depend on dominant species traits and are decoupled between above‐ and below‐ground biomass

Arid community responses to nitrogen and carbon addition depend on dominant species traits and are decoupled between above‐ and below‐ground biomass

Do xerophytic and mesophytic perennial grasses differ in soil resource capture and allocation? A field 15N experiment

Grazing exclusion reduces below‐ground biomass of temperate subhumid grasslands of South America: A meta‐analysis and a database

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Do xerophytic and mesophytic perennial grasses differ in soil resource capture and allocation? A field ¹⁵N experiment