Estructura poblacional de la palmera endémica Parajubaea torallyi (Mart.) Burret en zonas aprovechadas del Área Natural de Manejo Integrado El Palmar (Chuquisaca, Bolivia)
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Ecología en Bolivia
Abstract
Parajubaea torallyi es una palmera endémica de los valles interandinos de Bolivia, está considerada "en peligro" y es aprovechada localmente. Se realizó un estudio exploratorio de su población en el Área Natural de Manejo Integrado El Palmar (Chuquisaca). Se distinguieron ocho categorías de crecimiento en base a su morfología, altura, estado reproductivo y posibles presiones por el uso. Se evaluó su estructura poblacional por categorías de crecimiento en cinco zonas comunales con aprovechamiento, estableciendo por zona 3-4 parcelas temporales de 600 m². Se aplicó un análisis de conglomerados para ver si las similitudes en la estructura poblacional se daban a nivel de zonas o parcelas y un análisis de correspondencia para advertir el ordenamiento de las categorías en función a la densidad de las mismas. A nivel general, la estructura poblacional presentó una distribución a manera de J invertida, con buena representación de semillas, plántulas y juveniles (39.9%, 48.4% y 10%, respectivamente) y disminución casi exponencial de las siguientes categorías (0.8, 0.3, 0.1, 0.4 y 0.1%). A nivel local, la estructura poblacional varió entre zonas, existiendo dos tipos de distribuciones: una continua, a manera de J invertida y otra bimodal, discontinua, con reducida representación de juveniles y subadultas (≤ 0.1%). En el análisis de conglomerados las estructuras poblacionales se agruparon por zonas comunales. De acuerdo al análisis de correspondencia, la distribución de juveniles y subadultos estuvo inversamente correlacionada con la de palmeras mayores a 20 m. Se concluye que P. torallyi presenta indicios de auto-regeneración; pero, a nivel local tiene limitaciones en el reclutamiento de juveniles que podría ser resultado de la regulación poblacional denso-dependiente y la reducida disponibilidad de hábitats con condiciones adecuadas para su regeneración. La zonificación comunal reflejó diferencias en las características poblacionales de P. torallyi y puede ser útil para planificar su conservación y manejo.
Parajubaea torallyi is an endemic palm of the interandean valleys of Bolivia. It is considered "endangered" and is used locally. An exploratory study of its population was carried out in the Natural Area of Integrated Management El Palmar (Chuquisaca). Eight growth stages or categories were used on the basis of morphology, height, reproductive state and possible pressures from use. Its growth stage population structure was evaluated in five harvested communal zones, 3-4 temporary plots, each of 600 m², were located per communal zone of 600 m². Cluster analyses were carried out to see if similarities in population structure were given at the zone or plot level and an analysis of correspondence to detect categories as a function of density. In general, the population structure presented an inverted J distribution, with good presence of seeds, seedlings and juveniles (39.9%, 48.4% and 10% respectively) and an almost exponential decrease in the following stages (0.8, 0.3, 0.1, 0.4 and 0.1%). At the local level, population structure varied among zones, existing two types of distributions: a continuous one, like an inverted J and another bimodal, discontinuous, with reduced representation of juveniles and subadults (≤ 0.1%). In the cluster analyses population structures were grouped by communal zone. According to the cluster analyses, the distribution of juvenile and subadults was inversely correlated with that of palms taller than 20 m. We conclude that P. torallyi presents indications of regeneration but that at the local level it has limitations in juvenile recruitment that could be due to dense-dependent population regulation and reduced availability of habitat suitable for regeneration. The communal zonation used reflected differences in population characteristics of P. torallyi, and can be useful to plan its conservation and management.
Parajubaea torallyi is an endemic palm of the interandean valleys of Bolivia. It is considered "endangered" and is used locally. An exploratory study of its population was carried out in the Natural Area of Integrated Management El Palmar (Chuquisaca). Eight growth stages or categories were used on the basis of morphology, height, reproductive state and possible pressures from use. Its growth stage population structure was evaluated in five harvested communal zones, 3-4 temporary plots, each of 600 m², were located per communal zone of 600 m². Cluster analyses were carried out to see if similarities in population structure were given at the zone or plot level and an analysis of correspondence to detect categories as a function of density. In general, the population structure presented an inverted J distribution, with good presence of seeds, seedlings and juveniles (39.9%, 48.4% and 10% respectively) and an almost exponential decrease in the following stages (0.8, 0.3, 0.1, 0.4 and 0.1%). At the local level, population structure varied among zones, existing two types of distributions: a continuous one, like an inverted J and another bimodal, discontinuous, with reduced representation of juveniles and subadults (≤ 0.1%). In the cluster analyses population structures were grouped by communal zone. According to the cluster analyses, the distribution of juvenile and subadults was inversely correlated with that of palms taller than 20 m. We conclude that P. torallyi presents indications of regeneration but that at the local level it has limitations in juvenile recruitment that could be due to dense-dependent population regulation and reduced availability of habitat suitable for regeneration. The communal zonation used reflected differences in population characteristics of P. torallyi, and can be useful to plan its conservation and management.
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Vol. 44, No. 1