Efectos de la interacción del pastoreo y la inundación sobre Paspalum dilatatum, un pasto nativo de la Pampa Deprimida
Abstract
In this paper we test the hypothesis that, at the individual plant level, flooding and grazing induce opposit allocation responses. Removal of leaf area by grazing would produce a greater demand from the aboveground tissues, whereas the effects of the hypoxia provoked by flooding would increase the amount of resources demanded by belowground tissues. Therefore, at the individual-plant level, the combined effect of the two factors on plant growth would be negative. At the population level, we expect the existence of genetic variability on defoliation resistance and a trade-off between defoliation and flooding resistance. The hypothesis was tested by a factorial experiment with two levels offlooding (flooded vs un,flooded), defoliation (defoliated vs nondefoliated) and origin (permanent grazed area vs grazing exclosure). The experiment was performed with two clones of Paspalum dilatatum, a grass native from the Flooding Pampa grassland (Argentina). 37 days after the treatments were applied, the results showed that defoliation, acting isolated or combined with flooding, decreased biomass production by aproximately 30%, though it increased photosynthetic rate and stomatal conductance. Flooding affected none of these variables, but increased gas-filled root porosity. The clone from a grazed area had significantly higher root porosity (36% vs 32 %) than the clone from ca 10 year-old grazing exclosure. The results show that at the individual-plant level, the growth of P. dilatatum was not modified by flooding, acting isolated or combined with defoliation and that, at the population level, clones from grazed and ungrazed situations showed similar responses to dlefoliation and flooding.
References
Burdick, D.M. 1989. Root aerenchyma development in Spartina patens in response to flooding. American Journal of Botany 76:777-780.
Burkart, S.E., R.J.C. León y C.P. Movia. 1990. Inventario fitosociológico del pastizal de la Depresión del Salado (Prov. Bs. As.) en un área representativa de sus principales ambientes. Darwiniana 30:27-69.
Caldwell, M.M., J.H. Richards, D.A. Johnson, R.S. Nowak, R.S. Dzurec. 1981. Coping with herbivory: photosynthetic capacity and resource allocation in two semiarid Agropyron bunchgrasses. Oecologia 50:14-24.
Carman, J.G. y D.D. Briske. 1985. Morphologic and allozymic variation between long-term grazaed and non-grazed popula-tions of the bunchgrass Schizachyrium scoparium var. frequens. Oecologia 66:332-337.
Chaneton, E.J., J.M. Facelli y R.J.C. León. 1988. Floristic changes induced by flooding on grazed and ungrazed lowland zgrasslands in Argentina. Journal of Range Management 41:495-500.
Davy, A.J., S.M. Noble y R.P. Oliver. 1990. Genetic variation and adaptation to flooding in plants. Aquatic Botany 38:91-108.
Deregibus, V.A. y M. Cahuépé. 1983. Pastizales naturales de la Depresión del Salado: Utilización basada en conceptos ecológicos. Revista de Investigación Agropecuaria 18:47-77.
Defing, J.K. y E.L. Painter. 1983. Defoliation responses of western wheatgrass populations with diverse histories of prairie dog grazing. Oecologia 57:tá-71.
Etherington, J.R. 1984. Relationship between morphological adaptation to grazing, carbon balance and waterlogging tolerance in clones of Dactylis glomerata L. New Phytologist 98:647-658.
Hillel, D. 1971. Soil and water: physical principles and processes. Academic Press. New York.
Hurlbert, S.H. 1984. Pseudoreplication and the design of ecological field experiments. Ecological Monographs 54:187-211.
Insausti, P., E.J. Chaneton, A. Grimoldi y A. Soriano. 1993. Respuesta morfológica de Paspalum dilatatum (Poir.) a cambios en la relación R:RL asociados al efecto del pastoreo sobre el canopeo de plantas vecinas. Actas del XX Congreso de Fisiología Vegetal. Bariloche, Argentina. Pp 138-139.
Jackson, M.B. y M.C. Drew. 1984. Effects of flooding on growth and metabolism of herbaceous plants. En T.T. Kozlowski (ed): Flooding and plant growth. Academic Press, Orlando. Pp 47-128.
Justin, S.H.F. y W. Armstrong. 1987. The anatomical characteristics of roots and plant response to soil flooding. New Phytologist 106:465-495.
Kozlowski, T.T.. 1984. Plant responses to flooding of soil. Bioscience 34:162-167.
McNaughton, S.J. 1984. Grazing lawns: animals in herds, plant form, and coevolution. American Naturalist 124:863-886.
McNaughton, S.J. y F.S. Chapin. 1985. Effects of phosphorous nutrition and defoliation on C4 graminoids from the Serengucti plains. Ecology 66:1617-1629.
Naidoo, G. y S. Naidoo. 1992. Waterlogging responses of Sporobolus virginicus (L.) Kunth. Oecologia 90:445-450.
Oesterheld, M. y S.J. McNaughton. 1988. Intraspecific variation on the response of Themeda niandra to defoliation: the effect of time of recovery and growth rates on compensatory growth. Oecologia 77:181-186.
Oesterheld, M. 1990. Effect of grazing and flooding on plant growth and allocation (PhD Dissertation, Syracuse University).
Oesterheld, M. y S.J. McNaughton. 1991 a. Effect of stress and time for recovery on the amount of compensatory growth after grazing. Oecologia 85:305-313.
Oesterheld, M. y S.J. McNaughton. 1991b. Interactive effect of flooding and grazing on the growth of Serengeti grasses. Oecologia 88:153-156.
Oesterheld, M., O.E. Sala y S.J. McNaughton. 1992. Effect of animal hsubandry on herbivore carrying-capacity at a regional scale. Nature 356:234-236.
Sala, O.E. 1988. The effect of herbivory on vegetation structure. En Werger, M.J.A. (Ed) Plant Form and Vegetation Structu-re. S.P.B. Academic Publishing, The Hague. Pp 317-330.
Sala, O.E., M. Oesterheld, R.J.C. León y A. Soriano. 1986. Grazing effects upon plant community structure in subhumid grasslands of Argentina. Vegetatio 67:27-32.
Sala O. E., A. Soriano y S. Perelman. 1981. Relacionas hidricas de algunos componentes de tin pastizal de la Depresión del Salado. Revista de la Facultad de Agronomía 2:1-10.
Sokal, R.R. y F.J. Rohlf 1981. Biometry. Second edition. WH Freeman, San Francisco, California, USA. Pp 195-443.
Soriano, A. 1991. Río de la Plata Grasslands. En R.T. Coupland (ed.). Ecosystems of the World 8A. Natural Grasslands. Introduction and Western Hemisphere. Elsevier, New York. Pp 367-407.
Taboada, M. y R.S. Lavado. 1988. Gazing effects of the bulk density in a Natraquoll of the Flooding Pampa of Argentina. Journal of Range Management 41:500-503.
Toft, N.L., S.J. McNaughton y N.J. Georgiadis. 1987. Effects of water stress and simulated grazing on leaf elongation and water relations of an East African grass, Eustachys paspaloides. Australian Journal of Plant Physiology 14:211-226.
Wallace. L.L., S.J. McNaughton, M.B. Coughenour. 1984. Compensatory photosynthetic responses of three African graminoids to different fertilization, watering, and clipping regimes. Botanical Gazette 145:151-156.
Downloads
Published
How to Cite
Issue
Section
License
Authors retain their rights as follows: 1) by granting the journal the right to its first publication, and 2) by registering the published article with a Creative Commons Attribution License (CC-BY 4.0), which allows authors and third parties to view and use it as long as they clearly mention its origin (citation or reference, including authorship and first publication in this journal). Authors can make other non-exclusive distribution agreements as long as they clearly indicate their origin and are encouraged to widely share and disseminate the published version of their work.
