Dinámica de una población de Melocactus guitartii (Cactaceae) y su aplicabilidad para la conservación de la especie
Fecha
2017-07-04
Autores
Díaz Hernández, Ignacio David
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Editor
Universidad Central “Marta Abreu “ de Las Villas. Facultad de Ciencias Agropecuarias. Departamento de
Resumen
Melocactus guitartii es una cactácea endémica En Peligro Crítico, de la cual se conocen cinco poblaciones.
Se realizan acciones de manejo en dos de ellas, pero este manejo no está basado en el conocimiento profundo
de la dinámica de sus poblaciones. El principal objetivo de la presente tesis es caracterizar la dinámica de
la población ubicada en “Dagamal”, Sancti Spíritus; en relación con su viabilidad con vistas a optimizar el
manejo. Se estudió la germinación ex situ de las semillas frescas (con y sin mucílago) y dejadas secar
naturalmente dentro de los frutos, en dos sustratos diferentes. Se determinó la supervivencia ex situ de las
plántulas durante el primer año de vida. Se analizó las variaciones en la estructura poblacional a largo plazo
y se modeló la viabilidad de la población. Las semillas germinan mejor sobre serpentinitas. Además,
alrededor de tres meses de maduración post-cosecha aumentan la germinabilidad y disminuyen la dormancia
y efectos negativos del mucílago del fruto. La supervivencia ex situ de las plántulas durante el primer año
de vida es baja (~34%), pero están adaptadas a coexistir en altas densidades para modificar las condiciones
del ambiente y mejorar la tasa de supervivencia. La estructura de la población presenta oscilaciones
extremas del número de individuos amortiguadas a nivel de tamaño poblacional por un mecanismo de
denso-dependencia y presumiblemente facilitación intra-específica. La elevada estocasticidad de la
población aumenta su probabilidad de extinción y refuerza la necesidad de continuar el manejo y extender
el monitoreo al resto de las poblaciones
Melocactus guitartii is an endemic cactus listed as Critically Endangered, of which only five populations are known. Conservation oriented management is performed only upon two populations, but it is not based on a deep knowledge of the species’ populations dynamics. The main goal of this thesis is to characterize the dynamics of the population located in “Dagamal”, Sancti Spíritus; and its relationship with the populations’ viability, in order to optimize the management. The germination of fresh (with and without mucilage) seeds and seeds let dry inside the fruits, sowed on two different soils, was studied ex situ. The survival of the seedlings during the first year of life was also determined ex situ. Long term shift in the population’s structure was analyzed and a population’s viability analysis, based on the structure shift, was modeled. The seeds germinate better on serpentine soils. Also, about three months’ post-harvest time provides maturity and enhances germinability, reducing dormancy and the negative effect of the fruit’s mucilage. The survival ex situ of the seedlings was low (~34%), they seem to be adapted to live in high densities in order to modify the environment’s conditions and improve survival. The population structure presented dramatic shifts in the number of individuals, softened in terms of population size by a densitydependent mechanism and an intra-specific facilitation as well. The high stochasticity of the population raises its extinction probability and re-enforces the need to continue management actions and extend monitoring to the remaining populations.
Melocactus guitartii is an endemic cactus listed as Critically Endangered, of which only five populations are known. Conservation oriented management is performed only upon two populations, but it is not based on a deep knowledge of the species’ populations dynamics. The main goal of this thesis is to characterize the dynamics of the population located in “Dagamal”, Sancti Spíritus; and its relationship with the populations’ viability, in order to optimize the management. The germination of fresh (with and without mucilage) seeds and seeds let dry inside the fruits, sowed on two different soils, was studied ex situ. The survival of the seedlings during the first year of life was also determined ex situ. Long term shift in the population’s structure was analyzed and a population’s viability analysis, based on the structure shift, was modeled. The seeds germinate better on serpentine soils. Also, about three months’ post-harvest time provides maturity and enhances germinability, reducing dormancy and the negative effect of the fruit’s mucilage. The survival ex situ of the seedlings was low (~34%), they seem to be adapted to live in high densities in order to modify the environment’s conditions and improve survival. The population structure presented dramatic shifts in the number of individuals, softened in terms of population size by a densitydependent mechanism and an intra-specific facilitation as well. The high stochasticity of the population raises its extinction probability and re-enforces the need to continue management actions and extend monitoring to the remaining populations.
Descripción
Palabras clave
Melocactus guitartii, Germinación, Cactaceae, Endémica