Estructura poblacional del totaí (Acrocomia aculeata, Arecaceae) según presencia de ganado en localidades de Beni y Santa Cruz (Bolivia)
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Ecología en Bolivia
Abstract
Se comparó la estructura poblacional de la palmera totaí (Acrocomia aculeata) según la presencia de ganado bovino en bosques y sabanas de cinco localidades de San José de Chiquitos (Santa Cruz) y Trinidad (Beni) en Bolivia. En cada localidad se establecieron tres parcelas de 50 x 20 m. En los individuos de 26 cm de altura o más se registró: Altura total, DAP, número de pinnas, presencia de hojas maduras, espinas y racimos, y la presencia de ganado bovino por observación directa; además se contabilizó el número de plántulas en cinco micro-parcelas de 1 m². Se identificaron seis categorías de crecimiento: Plántula, juveniles 1 y 2, pre-adultos y adultos 1 y 2. En ambos municipios las poblaciones con ganado presentan mayor número de plántulas (95.4-96.9%), relativamente pocos juveniles (0.5-0.03%) y pre-adultos (0.3-0.08%), y niveles intermedios de adultos (3.8-2.9%). Esta tendencia corresponde a una curva de tipo II, donde existen niveles discontinuos de regeneración y alteraciones en el establecimiento de las plántulas. En las parcelas sin ganado encontramos dos patrones distintos. En Trinidad las plántulas y juveniles están casi ausentes (0-1.2%) y pre-adultos están reducidos (0.3%); esta tendencia corresponde a una curva de tipo III, con un nivel de regeneración severamente limitado. Mientras que San José presenta un tipo de gráfica de J invertida con individuos en todas las categorías de crecimiento y disminución exponencial desde la categoría plántula (50.9%) hasta adultos (27.9%), característica de una población auto-regenerativa. Estas observaciones sugieren que el ganado puede estar estimulando la regeneración a nivel de plántulas pero aparentemente estaría perjudicando el desarrollo de estas plántulas a los estadios de juveniles y pre-adultos, mientras que sin ganado existe una menor producción de plántulas únicamente en algunas situaciones. Se concluye que un manejo adecuado del ganado contribuiría a la conservación de esta palmera y se realizan recomendaciones al respecto.
The population structure of the Totaí palm (Acrocomia aculeata) was evaluated regarding the presence of cattle in forests and savannas of five locations in San José de Chiquitos (Santa Cruz) and Trinidad (Beni), Bolivia. Three plots of 50 x 20 m were settled down. For palms 26 cm tall or higher, the following measures were recorded: plant height, DBH, number of pinnae, presence of mature leaves, spines, and racemes, as well as the presence of cattle by direct observation. Furthermore, seedlings were registered in 1 m² microplots. Six growth categories were identified: seedling, juvenile 1 and 2, pre-adult, and adult 1 and 2. Places with presence of cattle showed a high number of seedlings (95.4-96.9%), few juveniles (0.5-0.03%) and pre-adults (0.3-0.08%), and intermediate levels of adults (3.8-2.9%). This trend fits into the population structure type II, where the levels of regeneration are discrete and seedling establishment is restricted. In plots without cattle in Trinidad, no seedlings and few juveniles (0-1.2%) were registered, while pre-adults were reduced (0.3%); this trend corresponds to the type III, with a severely limited regeneration level. San José presents an inverted J with individuals at all levels of growth and exponential decay from the seedling category (50.9%) to adult (27.9%), which is characteristic of a self-regenerating population. These tendencies suggest that cattle may contribute to seedling's regeneration but harm the juvenile and pre-adult phases, and on places without cattle few seedlings exist. In conclusion, good management strategies of cattle would contribute to the conservation of this palm and we give some recommendations about it.
The population structure of the Totaí palm (Acrocomia aculeata) was evaluated regarding the presence of cattle in forests and savannas of five locations in San José de Chiquitos (Santa Cruz) and Trinidad (Beni), Bolivia. Three plots of 50 x 20 m were settled down. For palms 26 cm tall or higher, the following measures were recorded: plant height, DBH, number of pinnae, presence of mature leaves, spines, and racemes, as well as the presence of cattle by direct observation. Furthermore, seedlings were registered in 1 m² microplots. Six growth categories were identified: seedling, juvenile 1 and 2, pre-adult, and adult 1 and 2. Places with presence of cattle showed a high number of seedlings (95.4-96.9%), few juveniles (0.5-0.03%) and pre-adults (0.3-0.08%), and intermediate levels of adults (3.8-2.9%). This trend fits into the population structure type II, where the levels of regeneration are discrete and seedling establishment is restricted. In plots without cattle in Trinidad, no seedlings and few juveniles (0-1.2%) were registered, while pre-adults were reduced (0.3%); this trend corresponds to the type III, with a severely limited regeneration level. San José presents an inverted J with individuals at all levels of growth and exponential decay from the seedling category (50.9%) to adult (27.9%), which is characteristic of a self-regenerating population. These tendencies suggest that cattle may contribute to seedling's regeneration but harm the juvenile and pre-adult phases, and on places without cattle few seedlings exist. In conclusion, good management strategies of cattle would contribute to the conservation of this palm and we give some recommendations about it.
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Vol. 48, No. 2