ecosistemas tropoandinos

1983. Inforrn. geogr. Chile 30: (pag. 25-45)

COMPARACION ENTRE DOS ECOSISTEMAS TROPOANDINOS:
LA PUNA CHILENA Y EL PARAMO ECUATORIANO
COMPARlSlON B M V E E N NVO TROPOANDEAN ECOSYSTEMS:
THE CHILEAN "PUNA" A N D THE ECUADORIAN "PARAMO"

VICTOR QUINTANILLA P.
Departamento de Geografia Universidad de Chile

ABSTRACT
This survey is a preliminary, comparative study of the phyto-ecologicfeatures of two great types
of ecosystems of the Andes mountain range.
It deals with the Chilean 'puna" in northern Chile (volcanic region of the Pallachatas, lsluga,
Guallatire, and Colorado hills al1 of which are over 6.000 m above sea level) and the Ecuador
paramos (volcanic regions of Cotopaxi and Rumiiiahui in the west and the central range of the
country).
Numerous samples were collectedin the field according to the Canfield lineal method and
the Braun-Blanquet one. The data were used to establish the frequency percentage, prevalence,
covering, and importance index of shrubs and herbaceous species representative of vegetal
formations. These groups were found on the vegetal range floor of the "puna"and 'paramo"
(over 3.000 m above sea level). They proved to have a very similarcomposition in gender and
family but they are different at the level of species. There were only two plants. Stipa-ichu and
dense Azorella which presented a high index of common representativeness in both ecosystems.
This botanical variety is mainly due to the different ways that the definitive ecological factors
affect the development of herbaceous species. In the "pararno", there are somefactors that help
the development of extensive shrub and herbaceous communities, such as, favourable exposition, high atmopheric humidity, and high rainfall. Al1 of these help provide a high degree of cover
a n d a dense physiognomy. Meanwhile, in the "puna" there are some factors, such as the high
atmospheric dryness, low rain fall, and the existence o f unfertile soils which are appropriatefor the
development of plants adapted to dryness, cold, and wind. They contribute to the formation of
open intermediate altitude shrubs and rangelands lower in altitude than in the 'paramo".
The comparative tables and the vegetal profiles show the predominance of herbaceous
species in the high mountain communities and the extense akitudinal distribution of these. Some
are living close to thelower limit of the eterna1 snows of the volcanoes.
Specific, morphological, and physiological functions of the plants would explain the great
ecologic adaptability of these species to exist in mountains over 5.000 m in altitude.

ANTECEDENTES Y OBJETIVOS
La intencion de este trabajo preliminar es entregar por el momento, una vision general del
ordenamiento de los tipos vegetales, de lacomposicion floristica y de la ecologia, en dos
ambientes biogeograficos de los Andes tropicales. En ellos se denotan semejanzas y diferencias

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INFORMACIONES GEOGRAFICAS

de formas de vida, particularmente, de modo global se comprueba que estos ecosisternas poseen
una ecologia fundamentalmente distinta, a pesar de localizarse en un rango altitudinal muy
similar. De acuerdo con el enfoquepropuesto por TROLL(1958) y aplicado posteriormente por
otros autores como Lauer, Cuatrecasas, Acosta Solis, etc., el termino tropoandino se refiere al
sector tropical altoandino de America Latina. Esta gran area!ropandina es exclusiva, y su ecologia
y vegetacion es distinta de las otras regiones tropicales de Africa, Asia y de las islas tropicales del
Pacifico. Ello se debe principalmente a lagran influencia orografica y altitudinal de los Andes.
La ecologia y flora de los sistemas montanosos no posee ambientes homologos en las
cordilleras andinas de America del Sur, a pesar de las caracteristicas ambientales similares que
presentan (CZJAKA,1968).
En varias regiones a lo largo de toda su extension, la cordillera andina se bifurca en grandes
brazos montanosos encerrando regiones...