Effects of defoliatingStipa tenuisandPiptochaetium napostaenseat different phenological stages: root growth

Becker, G. F.; Busso, Carlos; Montani, Tomás; Burgos, María; Flemmer, Andrea; Toribio, M.

doi:10.1006/jare.1995.0132

Cited by 24 publications

(17 citation statements)

References 47 publications

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“…Lack of root growth reduction after defoliation during 1996 agrees with the results of Becker et al (1997b) in this species after it was either defoliated at V or E, or remained undefoliated under rainfed conditions. Species relatively less tolerant of defoliation, such as S. tenuis when compared with S. clarazii (Saint Pierre et al 2000), can maintain root For personal use only.…”

Section: Root Numberssupporting

confidence: 83%

“…In August 1996, plants of S. clarazii defoliated at V under water stress again had a greater (P < 0.01) TRRN than undefoliated plants. These root system responses to defoliation are opposite to results reported in other perennial grass species under rainfed conditions (Becker et al 1997b;Engel et al 1998). A greater proportional carbon allocation to regrowing shoot sinks, to the expense for reducing root growth, has been reported as one mechanism conferring a greater competitive ability and defoliation tolerance to many perennial grasses (Briske and Richards 1995) Grazing tolerance in any given species, however, may not necessarily be explained by just one specific characteristic (Hendon and Briske 1997).…”

Section: Root Numbersmentioning

confidence: 73%

“…One of these vertical lines was used as a starting point for each set of observations. Further details on installation and use of the root periscope are provided by Becker et al (1997b).…”

Section: Potential Evapotranspirationmentioning

confidence: 99%

“…Studies on perennial grasses have demonstrated reductions in root length, increases or even no effect after defoliation, depending on the plant history and the timing, frequency or intensity of the defoliation (Becker et al 1997b;Engel et al 1998). Reductions in root growth after defoliation have been associated with grazing tolerance when linked to subsequent increases in the proportion of carbon allocation to regrowing shoots (Briske and Richards 1995).…”

mentioning

confidence: 99%

“…Annual rainfall in this area varies between 300 and 500 mm (Busso 1997). Some field studies in these rangelands have determined root growth, and root appearance and disappearance in native perennial grasses defoliated or not at different phenological stages (Distel and Fernández 1988;Becker et al 1997b). However, no study has yet addressed the cumulative effects of water stress with or without defoliation at various phenological stages on grass root growth, appearance or disappearance under field conditions.…”

mentioning

confidence: 99%

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Root growth, appearance and disappearance in perennial grasses: Effects of the timing of water stress with or without defoliation

Flemmer¹,

Busso²,

Fernández³

et al. 2002

Can. J. Plant Sci.

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, T. 2002. Root growth, appearance and disappearance in perennial grasses: Effects of the timing of water stress with or without defoliation. Can. J. Plant Sci. 82: 539-547. The effects of early and late defoliations were evaluated under different levels of soil water content on root growth, appearance and disappearance in Stipa clarazii Ball, S. tenuis Phil., and S. gynerioides Phil. Field studies were conducted in 1995, 1996 and early 1997. Stipa clarazii and S. tenuis are two important palatable perennial tussock grasses in temperate, semiarid rangelands of central Argentina, where S. gynerioides is one of the most abundant, unpalatable perennial grass species. We hypothesized that (1) root growth is reduced after defoliation at any phenological stage in S. clarazii and S. tenuis in comparison to undefoliated controls, (2) root growth, and root appearance and disappearance in all three species decrease as plant water stress increases, and (3) root growth associated with water stress in S. clarazii and S. tenuis is reduced comparatively less when plants are water-stressed earlier than later, or for a longer period of time during the growing season. Our results led us to reject hypothesis 1 and accept hypotheses 2 and 3. Maintenance of root growth after defoliation in S. clarazii and S. tenuis would allow these species a greater soil exploration and resource finding to sustain regrowth in their native, semiarid environments. tenuis sont deux importantes graminées vivaces comestibles poussant sur les buttes de gazon dans les grands parcours semi-arides du centre de l'Argentine, où S. gynerioides demeure l'une des plus abondantes graminées vivaces impropres à la consommation pour le bétail. Les auteurs ont formulé diverses hypothèses : 1) que les racines de S. clarazii et S. tenuis croissent plus lentement après la défoliation, peu importe le stade phénologique, comparativement aux plants témoins non défoliés; 2) que la croissance, la naissance et la mort des racines diminuent à mesure que le stress hydrique s'aggrave chez les trois espèces; 3) que le ralentissement de la croissance des racines associé au stress hydrique chez S. clarazii et S. tenuis est moins grand quand le stress survient au début de la période végétative que quand il survient plus tard ou se prolonge. Les résultats ont amené les auteurs à rejeter la première hypothèse et à retenir les deux autres. En poursuivant leur croissance après la défoliation, les racines de S. clarazii et de S. tenuis permettraient aux deux espèces d'explorer le sol davantage et de découvrir d'autres ressources qui les aideront à survivre dans leur milieu naturel, semi-aride.

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Section: Root Numberssupporting

confidence: 83%

Section: Root Numbersmentioning

confidence: 73%

“…One of these vertical lines was used as a starting point for each set of observations. Further details on installation and use of the root periscope are provided by Becker et al (1997b).…”

Section: Potential Evapotranspirationmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Root growth, appearance and disappearance in perennial grasses: Effects of the timing of water stress with or without defoliation

Flemmer¹,

Busso²,

Fernández³

et al. 2002

Can. J. Plant Sci.

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Towards an increased and sustainable production in semi-arid rangelands of central Argentina: two decades of research

Busso

1997

Journal of Arid Environments

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Are fine roots of both shrubs and perennial grasses able to occupy the upper soil layer? A case study in the arid Patagonian Monte with non-seasonal precipitation

2007

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We tested whether both shrubs and grasses are able to develop similar active fine-root systems in the upper soil layer of the arid Patagonian Monte ecosystem with non-seasonal precipitation. We selected in the field shrub patches consisting of one isolated modal plant of the dominant shrub Larrea divaricata Cav., grass patches formed by one or more bunches of the dominant grass Stipa tenuis Phil. (15 cm diameter), and mixed patches consisting of one individual of L. divaricata with bunches of S. tenuis under its canopy. We assessed the biomass, regrowth, and activity of fine roots (diameter <1.4 mm) of each species in the upper soil (50 cm depth) of each patch type at 3-month intervals. We also measured the N concentration in fine roots to estimate the relative contribution of each species to fine-root biomass of mixed patches. We injected Li + in the soil as a chemical tracer to detect fine-root activity of each species in the upper soil. Fine-root biomass was higher in mixed patches than in grass patches while fine-root biomass in shrub patches did not differ from the two former. We did not find differences in fine-root regrowth among patch types. Li + injection provided evidence of active fine roots of both species in the upper soil when it was wet. N concentration in fine roots suggested the prevalence of fine roots of L. divaricata in the upper soil of mixed patches. Our results support evidence of the ability of fine roots of both the shrub and the grass species to occupy the upper soil. These findings did not support the two-layer model (H Walter, Ecology of tropical and subtropical vegetation, Oliver and Boyd, Edinburgh, 1971) and provide evidence of this model would be less applicable to arid ecosystems with non-seasonal precipitation. Further, our results highlighted some issues deserving more research such as the outcome of belowground competition between neighboring plants of both contrasting life forms, the eventual limited fine-root carrying capacity of the upper soil, and differences in fine-root lifespan between species of both contrasting life form.

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Effects of defoliatingStipa tenuisandPiptochaetium napostaenseat different phenological stages: root growth

Cited by 24 publications

References 47 publications

Root growth, appearance and disappearance in perennial grasses: Effects of the timing of water stress with or without defoliation

Root growth, appearance and disappearance in perennial grasses: Effects of the timing of water stress with or without defoliation

Towards an increased and sustainable production in semi-arid rangelands of central Argentina: two decades of research

Are fine roots of both shrubs and perennial grasses able to occupy the upper soil layer? A case study in the arid Patagonian Monte with non-seasonal precipitation

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