Guanacos, spiny shrubs and the evolutionary history of grazing in the Patagonian steppe
Abstract
Field observations while traveling through the Patagonian steppe over the past 15 years have left me with a clear impression of how well defended many of the plants are against herbivory. The objectives of this paper are to question the prevailing hypothesis that the evolutionary history of herbivory in Patagonia has been short and to ask if there is any evidence to support an alternative hypothesis of a long evolutionary history. The analysis is entirely speculative based upon personal observations, discussions with colleagues and a diverse selection of material from the literature. My conclusion from this analysis is that there is at least enough support for an alternative hypothesis to justify proposing it. Furthermore, the long evolutionary history hypothesis is consistent with observations of frequent herbivore defenses among the dominant plants and relative resistance of upland sites to large negative effects of 100 years of herbivory by sheep.
References
Coughenour, M.B. 1985. Graminoid responses to grazing by large herbivores: adaptations, exaptations and interacting processes. Annals of the Missouri Botanical Gardens 72:852-863.
Fernández, R.J., O.E. Sala and R.A. Gollucio. 1991. Woody and herbaceous aboveground production of a Patagonian steppe. Journal of Range Management 44:434-437.
Franklin, W.L. 1982. Biology, ecology and relationship to man of the South American camelids. Pp. 457-489. In: Mares, M.A. and H.H. Genoways(eds.).Mammalian biology in South America. Pymatuning Symposium Ecology speical Publication Series Volume 6, University of Pittsburgh, Pittsburgh.
Franklin, W.L, F. Bas, C.F. Bonacic, C. Cunazza and N. Soto. 1997. Striving to manage Patagonia guanacos forsustained use in the grazing agroecosystems ofsouthern Chile. WildlifeSociety Bulletin 25:65-73.
Keast, A. 1972. Comparison of contemporary mammal faunas ofsouthern continents.Pp. 433-501. In: Keast, A.,F.C. Erk andB. Glass(eds.). Evolution, mammals and southern continents.State University New York Press, Albany.
Lauenroth,W.K. 1979. Grassland primary production: North American grasslandsin perspective.Pp. 3-24.In: French, N.R.(ed.).Perspectivesin Grassland Ecology. Ecol.Studies Vol. 32,Springer-Verlag, New York.
Livingston, H.G., W.J.A.Payne and M.T.Friend. 1962. Urea excretion in ruminants. Nature 194:1057-1058.
Markgraf, V. 1985. LatePleistocene faunal extinctionsin southernPatagonia.Science 228:1110-1112.
Milchunas, D.G., O.E.Sala, and W.K. Lauenroth. 1988. A generalized model ofthe effects of grazing by large herbivores on grassland community structure. American Naturalist 132:87-106.
Milchunas, D.G. and W.K. Lauenroth. 1993. A quantitative assessment of the effects of grazing on vegetation and soils over a global range of environments. Ecological Monographs 63:327-366.
Miller,R.F.,T.J.Svejcar andN.E.West. 1994.Implications oflivestock herbivory in the intermountain sagebrush region:Plant composition.Pp. 101-146. In: Vavra, M., W.A. Laycock and R.D.Pieper, (eds.). Ecological implications of livestock herbivory in the West.Society for Range Management, Denver.
Paruelo, J.M., E.G. Jobbágy, O.E. Sala, W.K. Lauenroth and I.C. Burke. 1998. Functional and structural convergence of temperate grassland and shrubland ecosystems. Ecological Applications 8:194-206.
Raedeke, K.J. 1979.Population dynamics and socioecology of the guanaco (Lama guanicoe) of Magallenes, Chile.Ph.D. Thesis, University of Washington, Seattle. 404 pp.
Sala, O.E., W.J. Parton, L.A. Joyce, and W.K. Lauenroth. 1988. Primary production of the central grassland region of the United States: Spatial pattern and major controls. Ecology 69:40-45.
Schmidt-Nielsen, B., K. Schmidt-Nielsen, T.R. Houpt and S.A. Jarnum. 1957. Urea excretion in the camel. Mammalia 20:477-483.
Schlichter, T.M., R.J.C. Leon and A. Soriano. 1978. Utilización de indices de diversidad en la evaluación de pastizales naturales en el centro-oeste de Chubut. Ecología 3:125-132.
Somlo,R. 1997.Atlas dietarios de herbívorosPatagónicos.Prodesar-INTA-GTZ,ImprentaBavaria,Barioloche. 109 pp.
Walter, H. 1971. Ecology of tropical and subtropical vegetation. Oliver and Boyd, Edinburgh. 539 pp.
Young, J.A., R.A. Evans and J. Major. 1972. Alien plants in the Great Basin. Journal of Range Management 25:194-201.
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.