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University of Basel (2012)

Effects of grazing and fire on herbaceous species in the Bolivian Altiplano

Aguilar, Lita Beatriz Patty

Titre  : Effects of grazing and fire on herbaceous species in the Bolivian Altiplano

Auteur : Aguilar, Lita Beatriz Patty

Université de soutenance : University of Basel

Grade : Doctor of Philosophy (PhD) 2012

Résumé
High mountain rangelands had been under human land use for millennia in most parts of the world. Traditional land care systems led to highly diverse and stable ecosystems. As these traditions fade and population pressure rises, these grassland systems become overgrazed, lose carrying capacity and biodiversity and become eroded. Semi-arid high elevation pastures in tropical and subtropical regions are particularly endangered. This PhD project aimed at assessing the plant inventory, the productivity and sensitivity of the herbaceous fraction of the flora to grazing by camelids in the Festuca orthophylla tall-tussock-dominated puna called ’pajonal’ in the Bolivian Altiplano at 4250 m elevation (Sajama National Park 18°08’S, 68°58’W), with annual temperatures around 8.8 °C, the minimum and maximum temperatures were -5.9 and 31.0°C during the 2006-2008 observation period. This area receives between 250 and 350 mm of rainfall during a short (3-4 month) rainy season from December to March, this is also the growing season of the herbaceous species. The Sajama village has a population of about 150 families, with a long tradition in husbandry of llamas (53%), alpacas (39%) and sheep (8%). My project was divided in three tasks, (1) a characterization of the herbaceous inter- and intra tussock flora, (2) a productivity assessment of the herbaceous pajonal components under various treatments, and (3) a study of soil seed banks and erodibility. The biology and productivity of Festuca orthophylla was investigated in a parallel PhD project (by José Monteiro). (1) Biomass allocation in herbaceous plants under grazing impact in the high semi-arid Andes Besides developmental controls, assimilatory and respiratory processes as well as allocation of photo-assimilates to certain plant compartments are driving the rate of plant growth. These relationships are explored in what has been termed ’functional growth analysis’.

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