Abstract

TEIXEIRA ROTH, Vanessa; CASTRO CEPERO, Viviana; CERONI STUVA, Aldo  and  EYZAGUIRRE PEREZ, Raúl. Diversity and density of a cacti community in the Chillón river valley: Umarcata hill and Orobel valley and their relationship with the soil factors. Ecol. apl. [online]. 2004, vol.3, n.1-2, pp.1-8. ISSN 1726-2216.

Few studies of vegetation conducted in arid zones have associated soil factors with plant associations. In our study we try to understand which are the most important soil factors that affect composition, distribution and structure of the community. The cacti community was studied at Umarcata Hill and Orobel Valley of the Chillon River Basin. A simple random sampling was carried out in square 15 meter sided plots, with 14 plots per area. Every area was divided into three zones: high, medium and low. Soil samples were analyzed to determine potassium, phosphorus, and organic matter concentration, pH, electrical conductivity and calcium carbonate percentage. The diversity values at Umarcata Hill lie in the rank from 0.75 to 1.789 bits / individual, whereas in Orobel Valley they rank from 1.22 to 1.88 bits / individual. In the latter, specific diversity and equity are higher indicating a stable and organized community. Phosphorus (15 to 42 ppm) and potassium (300 to 800 ppm) are the factors that limit cacti growth in the community. Electric conductivity (0.3 dS/m) is related to diversity due to the fact that it measures soil salinity, which in turn affects plant growth.

Keywords : Diversity; density; soil factors; community of cacti; limiting factors.

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