Is the zone of influence colonized by roots of neighboring species? Field tests in a Patagonian steppe

Reyes, María Fernanda; Aguiar, Martı́n R.

doi:10.1016/j.jaridenv.2016.10.012

Cited by 10 publications

(20 citation statements)

References 13 publications

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“…These patterns demonstrate that, at microsite level, the above‐ground portion of vegetation is more territorial, while the below‐ground portion is considerably intermingled or mixed (lack of root system segregation; Leva et al. ; Reyes & Aguiar ). Similar patterns were found in other grasslands, where below‐ground fine‐scale richness was up to two times larger than above‐ground richness, indicating that conventional above‐ground studies of plant richness may overlook many co‐existing species (Hiiesalu et al.…”

Section: Discussionmentioning

confidence: 98%

“…This key uses root morphological traits that differ among species, such as diameter, colour and branching. This method is >90% precise (Reyes & Aguiar 2017). The sandy soil texture facilitated root separation, because soil particles are easily detached from roots (Leva et al 2009).…”

Section: Estimation Of Grazing Effects On Root Biomass and On Below-amentioning

confidence: 99%

“…; Price et al. ; Reyes & Aguiar ). In general, it is accepted that plant species co‐existence results from root system segregation in space at very fine scales (Schenk ).…”

Section: Introductionmentioning

confidence: 99%

“…There are relatively few studies that have resolved the difficulty of identifying species through their roots (using molecular techniques or noticeable root traits). They found that different species share the same soil volume (Pech a ckov a et al 1999;de Kronn & Mommer 2006;Mommer et al 2008Mommer et al , 2010Leva et al 2009;Frank et al 2010Frank et al , 2015Hiiesalu et al 2012;de Kronn et al 2012;Price et al 2012;Reyes & Aguiar 2017). In general, it is accepted that plant species co-existence results from root system segregation in space at very fine scales (Schenk 2006).…”

Section: Introductionmentioning

confidence: 99%

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Fine‐scale root community structure and below‐ground responses to grazing show independence from above‐ground patterns

Oñatibia

Reyes

Aguiar

2017

J Vegetation Science

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Question: Root biomass distribution and below-ground processes are the main drivers of plant community structure and dynamics in arid rangelands. However, despite their relevance, below-ground plant responses to disturbance regimes remain poorly understood. This knowledge is a pressing issue since most of our ideas derive from extrapolating above-ground ecological theory and data. Here, we asked how domestic grazing management changes (intensification and abandonment) impact on both below-ground species co-occurrence at microsite level (point-richness) in relation to above-ground patterns and below-ground biomass distribution of dominant graminoid species across different soil layers.Location: Patagonian steppe, Argentina. Methods:We sampled and compared ungrazed, moderately grazed and intensively grazed steppes. We evaluated below-and above-ground point-richness (microsite level: 6-cm diameter), as well as total and specific root biomass in the top 20 cm of soil along 50-m transects in commercial paddocks. Results:We found independence between fine-scale below-and above-ground responses. Below-ground point-richness was at least three times higher than above-ground point-richness. Besides, below-ground point-richness decreased from 4.2 species in ungrazed sites to 3.4 species in intensively grazed ones. Neither grazing intensification nor abandonment changed total root biomass, although intensification changed the root biomass composition, reducing preferred and increasing non-preferred grass species. Strikingly, below-ground point-richness and total root biomass did not differ between microsites covered and not covered by vegetation. This pattern was not affected by grazing.Conclusions: Our findings showed a higher degree of fine-scale below-ground species co-occurrence than above-ground in this Patagonian steppe. The intensification of grazing slightly decreased below-ground species co-occurrence and changed root composition (species abundance), although grazing management did not modify the high degree of independence between below-and aboveground structure. Even though intensive grazing markedly decreases aboveground biomass, total below-ground biomass does not vary along a wide range of grazing conditions. In general, most of our knowledge about vegetation responses to grazing is based on above-ground information, assuming that below-ground patterns and processes are analogous to those above-ground. This study suggests that below-and above-ground community structure at fine-scale are not strongly correlated and they can be differentially affected by grazing.

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Section: Discussionmentioning

confidence: 98%

Section: Estimation Of Grazing Effects On Root Biomass and On Below-amentioning

confidence: 99%

“…; Price et al. ; Reyes & Aguiar ). In general, it is accepted that plant species co‐existence results from root system segregation in space at very fine scales (Schenk ).…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Fine‐scale root community structure and below‐ground responses to grazing show independence from above‐ground patterns

Oñatibia

Reyes

Aguiar

2017

J Vegetation Science

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“…Previous studies allowed taxonomic identification of roots of species growing under field conditions by their morphology with 95% accuracy (Leva et al . ; Reyes & Aguiar ). As nitrogen is a critical resource for xeric plants (Austin ), we evaluated root growth with soil without roots and with or without nitrogen fertilisation to create a heterogeneous microsite.…”

Section: Introductionmentioning

confidence: 99%

Root proliferation strategies and exploration of soil patchiness in arid communities

Reyes

Aguiar

2017

Austral Ecology

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Soil patchiness is a key feature of arid rangelands. As root proliferation contributes to soil exploration and resource uptake, it is ecologically relevant to understand how species respond to soil heterogeneity and coexist. Campbell et al.'s influential 1991 hypothesis proposes that dominant species deploy root systems (scale) that maximize soil volume explored. Instead, subordinate species show accurate root systems that exclusively proliferate in nutrient‐rich patches (precision). After many experiments under controlled conditions, the generality of this hypothesis has been questioned but a field perspective is necessary to increase realism in the conceptual framework. We worked with a guild of perennial graminoid species inside a grazing exclosure in an arid Patagonian steppe, a model system for ecological studies in arid rangelands for four decades. We buried root traps in bare ground patches with sieved soil, with or without a pulse of nitrogen addition, to measure specific root biomass and precision at 6 and 18 months after burial. We also estimated scale (root density) in naturally established plants, and root decomposition in litter bags. Several species grew in root traps. Dominant species showed the highest root biomass (in both harvests) and scale. Subordinate species grew more frequently with nitrogen addition and showed lower biomass and scale. Similar total root biomass was found with and without nitrogen addition. Species differed in root decomposition, but correcting species biomass by decomposition did not change our conclusions. We did not find a relation between scale and precision, indicating that Campbell's hypothesis is probably not supported in this Patagonian steppe. Soil resource acquisition differences probably do not utterly explain the coexistence of dominant and subordinate species because the steppe is also affected by large herbivore grazing. We propose that root proliferation in this steppe is the result of the interaction between individual density in the community and specific root growth rates.

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Temporal and spatial variability in soil CO2 efflux in the patagonian steppe

et al. 2019

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Is the zone of influence colonized by roots of neighboring species? Field tests in a Patagonian steppe

Cited by 10 publications

References 13 publications

Fine‐scale root community structure and below‐ground responses to grazing show independence from above‐ground patterns

Fine‐scale root community structure and below‐ground responses to grazing show independence from above‐ground patterns

Root proliferation strategies and exploration of soil patchiness in arid communities

Temporal and spatial variability in soil CO2 efflux in the patagonian steppe

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