Fertilization of a Native Grassland in the Depresion del Rio Salado', Province of Buenos Aires: Herbage Dry Matter Accumulation and Botanical Composition

Ginzo, H. D.; Collantes, Marta B.; Caso, O. H.

doi:10.2307/3898513

Cited by 22 publications

(20 citation statements)

References 3 publications

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“…Positive effects of nitrogen fertilization are frequently found in natural grasslands (Clark and Woodmansee 1992). However, in the Flooding Pampa phosphorus is considered as the most limiting nutrient (Ginzo et al 1982(Ginzo et al , 1986Marchegiani et al 1982;Pruess et al 1992). This work shows that nitrogen is also a limiting factor.…”

Section: Discussionmentioning

confidence: 99%

Effects of grazing pattern and nitrogen availability on primary productivity

Semmartin

Oesterheld

2001

Oecologia

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A major part of the impact of grazing on primary productivity results from the joint action of tissue removal and nutrient return to the soil via dung and urine. Grazing, however, is not uniformly distributed in space: grazed grasslands show a matrix of grazed and ungrazed patches, which in turn, may or may not be affected by faecal or urine deposition. This paper investigates the effects of grazing spatial pattern and nitrogen availability on primary productivity. We propose that grazed plants located at the edge of a grazed patch are more shaded by their taller ungrazed neighbours than plants at the center. Since the border effect is less important as patch size increases, the effects of grazing will be more positive, or less negative, when grazing pattern is coarse-grained than when it is fine-grained. We also propose that nitrogen availability will affect this response to grazing through its effects on the intensity of competition for light and on the amount of compensatory growth. We performed a field experiment in a grassland community of the Flooding Pampa, Argentina, in which we compared the productivity of undefoliated controls and defoliated patches of different size, with and without nitrogen application. Defoliation reduced primary productivity and this effect was greater in the smallest, fertilized patches. Productivity was highest at patches of intermediate and large sizes. Nitrogen addition increased productivity by two-fold. The integrated photon flux density reaching the base of the canopy was affected by defoliation and by patch size: it was lower in controls than in defoliated patches and increased with patch size. Our results showed that (a) the size of the defoliated patch modified the response of this grassland to defoliation, (b) this response was correlated with light availability, and

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Section: Discussionmentioning

confidence: 99%

Effects of grazing pattern and nitrogen availability on primary productivity

Semmartin

Oesterheld

2001

Oecologia

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“…During the last two centuries, grazing by introduced herbivores has been a common disturbance in the region, and has modiWed both the structure and functioning of grasslands by promoting changes in canopy structure, species richness and above-ground primary production (Sala et al 1986;Rusch and Oesterheld 1997). Other common disturbances such as fertilizations and natural Xooding events increase soil P availability (Ginzo et al 1982;Rubio et al 1997;García et al 2002;Semmartin et al 2007). Thus, in this system, accumulation of P reserves during nutrient Xuxes likely represents an ecological advantage when considering frequent defoliation by herbivores.…”

Section: Speciesmentioning

confidence: 99%

“…This hypothesis predicts that regrowth following defoliation will be larger for plants that accumulated P during a previous period. We performed two experiments with four grass species which are dominant and co-dominant in the Flooding Pampa grasslands, an area where P luxury consumption is a common response, both at functional group and individual level (Ginzo et al 1982;Rubio and Lavado 1999;Semmartin et al 2007). The Wrst experiment, aimed at generating P luxury consumption by fertilization, resulted in one species (Sporobolus indicus) showing luxury consumption.…”

Section: Introductionmentioning

confidence: 99%

Phosphorus reserves increase grass regrowth after defoliation

Oyarzábal

Oesterheld

2009

Oecologia

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Accumulation of P above levels that promote growth, a common plant response called "luxury consumption", can be considered as a form of reserve to support future growth when the nutrient can subsequently be mobilized. However, the effect of P reserves on regrowth following defoliation has not been demonstrated. We tested the hypothesis that P luxury consumption increases plant tolerance to defoliation. We performed two experiments with four grass species from a continuously grazed temperate grassland in the Flooding Pampa (Argentina). The first experiment, aimed at generating P luxury consumption by fertilization, resulted in one species (Sporobolus indicus) showing luxury consumption. In this way, we were able to obtain plants of S. indicus with similar biomass but contrasting amounts of P reserves. The second experiment evaluated the subsequent regrowth following defoliation on a P-free medium of these plants differing in P reserves. Regrowth was larger for plants that had shown P luxury consumption during a previous period than for plants with lower levels of P reserves. During regrowth these plants showed a clear pattern of P remobilization from the stubble, crown, and root compartments to the regrowing tissue, in addition to a likely reutilization of P present in leaf-growth zones. This work is the first showing that high levels of P reserves can confer tolerance to defoliation by promoting compensatory growth under P deficiency.

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“…Changes in soil resources have been shown to influence community structure. Fertilization of an area can lead to dramatic shifts in species composition and diversity (Milton 1947;Willis and Yenn 1961;Specht 1963;Ginzo et al, 1982;Tilman 1982Tilman , 1984. Tilman (1986) suggests that it is possible to predict the effect of resource availability on community structure and succession if the resource-dependent plant growth is known.…”

Section: Literature Reviewmentioning

confidence: 99%

Historical Botany of the Romero Cabin: A Family Homestead on the Pajarito Plateau

Foxx¹,

Tierney²

1999

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Fertilization of a Native Grassland in the Depresion del Rio Salado', Province of Buenos Aires: Herbage Dry Matter Accumulation and Botanical Composition

Cited by 22 publications

References 3 publications

Effects of grazing pattern and nitrogen availability on primary productivity

Effects of grazing pattern and nitrogen availability on primary productivity

Phosphorus reserves increase grass regrowth after defoliation

Historical Botany of the Romero Cabin: A Family Homestead on the Pajarito Plateau

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