Saturday, 15 July 2006

Overexplotation and Quality of Altoandines Soils: Study Case of Apolobamba (Bolivia).

Mª Ángeles Muñoz García, Univ Politécnica de Cartagena, Alfonso XIII, 52, Cartagena, 30203, Spain and Ángel Faz Cano, Univ Politécnica de Cartagena, Alfonso XIII, 52, Cartagena, Spain.

Ecosystems in the puna or grasslands of the Altiplane are degraded, in many cases, by anthrop activities, more over by excessive cattle raising. It is the natural habitat for the domestic and wild camelids. Between the second ones is the vicuña (Vicugna vicugna), endangered specie by The World Conservation Union (IUCN). The National Management Integrated Natural Area Apolobamba (ANMIN-A), is located in Norwest La Paz Department and it is hosting more than 10 000 specimens of vicuñas, distributed in around 120 000 ha. Through to the efforts of the Apolobamba population, government authorities and international organisms, the vicuña is managed as an example of sustainable use of the biodiversity by indigenous communities. The Universidad Politécnica de Cartagena has carried out a research to determinate the natural resources situation in the habitat of the vicuña in Apolobamba, through the collaboration of the “Programa Araucaria” (Agencia Española de Cooperación Internacional). The objective of this work is the evaluation of the soil affectation degrees in the puna of ANMIN-A, taking into account the different densities of vicuñas according to census made during the last years. In this work, analysis of edaphological, quality, and degradation by macro morphological and physic-chemical characterization of the soils have been made in four census places with different densities of vicuña: Ulla-Ulla, low density of vicuña; Ucha-Ucha, medium density; Caballchiñuni, high density; and Puyo-Puyo, very high density. The plots are of 5x5 m in each census place. In each plot, three sampling points at two depths, 0-5 cm and 5-15 cm. The following determinations were carried out: organic carbon, total nitrogen, C/N relation, calcium carbonated, available phosphor, cation exchange capacity , Na+, Mg2+, K+, pH, electrical conductivity, texture, moisture and bulk density. Results obtained show that in Ucha-Ucha and Caballchiñuni, the contents of carbon, nitrogen and macronutrients are medium, for natural soils of these characteristics. In Puyo-Puyo it has been recognised a high content of organic carbon, more over in the surface horizon. It is a soil with a good plant cover with native species of Pycnophyllum grassland. In the other hand, in Ulla-Ulla these contents are reduced with high C/N relation and low levels of pH and electrical conductivity. In conclusion, it seems to be, therefore, that the census places with the highest vicuña density and the most steeply orography, show high contents of organic carbon and total nitrogen; however, where there is little number of vicuñas, the content of these elements are produced, mainly, by an organic contribution. This contribution must be originated by the few plants of the zone and, mainly, by the domestic camelids slurries (more than vicuñas), which are producing an excessive pressure in this soil promoting important erosive process and the partial transformation of the plant cover.

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