Efecto de la fragmentación del hábitat sobre la remoción dispersiva de fruto y la depredación post-dispersiva de semillas de Ziziphus lotus (Rhamnaceae) en el sureste semiárido de la Península Ibérica
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2016-03-02
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Jaén: Universidad de Jaén
Resumen
[ES] La fragmentación del hábitat, junto con el cambio climático, es una de las principales causas de la pérdida de biodiversidad actualmente en nuestro planeta. Uno de los factores ecológicos responsables del mantenimiento y regeneración de las poblaciones, que se ve gravemente afectado por la fragmentación y pérdida de hábitat es la conectividad ecológica. Mediante este estudio se pretende analizar cuál es el efecto de la fragmentación del hábitat sobre la dispersión y depredación de semillas de Ziziphus lotus. Esta especie cuenta con una distribución muy reducida en España, limitándose al sureste semiárido, y la gran explotación de esta zona por la agricultura intensiva (cultivos bajo plástico) ha reducido considerablemente la distribución de Z. lotus, una especie clave en este tipo de ecosistemas. Esta especie, además de ser un recurso alimenticio por los frutos que produce para numerosos animales, es un fijador del sustrato, y crea islas de vegetación que dan sustento a gran número de especies vegetales, y refugio a especies animales. Se han realizado dos experimentos en siete poblaciones con diferente grado de alteración antrópica, por un lado se ha contabilizado la lluvia de semillas, y se ha desarrollado un experimento para analizar la dispersión mediante tarrinas con frutos, y por otro un experimento para evaluar la depredación mediante semillas pegadas en una malla. También se ha llevado a cabo un conteo de la abundancia de roedores y lagomorfos, mediante el trampeo y el conteo de letrinas respectivamente. Los resultados obtenidos indican que la alteración del hábitat tiene un efecto negativo sobre la remoción de frutos, también se aprecia que esta alteración tiene un efecto sobre la abundancia de lagomorfos, aumentándola, con el consiguiente efecto negativo que trae consigo la depulpación causada por estos. Podemos concluir por tanto, que afectando a ciertas interacciones con animales que suceden en el ciclo dispersivo de la especie, la fragmentación supone una amenaza importante para la persistencia de las poblaciones de Ziziphus lotus en el sureste semiárido.
[EN] Habitat fragmentation, along climate change, is currently one of the main causes of biodiversity loss on our planet. One of the ecological factors responsible for the maintenance and regeneration of population, which is seriously affected by the fragmentation and loss of habitat, is the ecological connectivity. The purpose of this study is to analyze the effect of habitat fragmentation on seed dispersal and predation of Ziziphus lotus. This species has a very limited distribution in Spain, only located on the semiarid southeast; the great exploitation of this area for intensive agriculture (crops under plastic) has significantly reduced the distribution of Z. lotus, a key species in these ecosystems. This species, besides being a food source because of the fruits it produces for many animals, is a fixing substrate, and creates islands of vegetation that sustain large number of plant species, and shelter for animals. Two experiments were performed in seven populations with different degrees of anthropogenic alteration, on the one hand has posted seed rain, and has developed an experiment to analyze the dispersion by tubs with fruit, on the other hand an experiment to evaluate predation using seeds to a mesh. We have also carried out a counting of the abundance of rodents and lagomorphs, by trapping and counting latrines respectively. The results indicate that habitat alteration has a negative effect on fruit removal, also it shows that this condition has an effect on the abundance of lagomorphs, which has a negative effect brings depulpation caused by these. We can conclude that fragmentation affects in a negative way to the interactions between animal and plants that happens in the dispersive cycle of the species and, therefore this represents a threat for the persistence of populations of Ziziphus lotus on the semiarid southeast.
[EN] Habitat fragmentation, along climate change, is currently one of the main causes of biodiversity loss on our planet. One of the ecological factors responsible for the maintenance and regeneration of population, which is seriously affected by the fragmentation and loss of habitat, is the ecological connectivity. The purpose of this study is to analyze the effect of habitat fragmentation on seed dispersal and predation of Ziziphus lotus. This species has a very limited distribution in Spain, only located on the semiarid southeast; the great exploitation of this area for intensive agriculture (crops under plastic) has significantly reduced the distribution of Z. lotus, a key species in these ecosystems. This species, besides being a food source because of the fruits it produces for many animals, is a fixing substrate, and creates islands of vegetation that sustain large number of plant species, and shelter for animals. Two experiments were performed in seven populations with different degrees of anthropogenic alteration, on the one hand has posted seed rain, and has developed an experiment to analyze the dispersion by tubs with fruit, on the other hand an experiment to evaluate predation using seeds to a mesh. We have also carried out a counting of the abundance of rodents and lagomorphs, by trapping and counting latrines respectively. The results indicate that habitat alteration has a negative effect on fruit removal, also it shows that this condition has an effect on the abundance of lagomorphs, which has a negative effect brings depulpation caused by these. We can conclude that fragmentation affects in a negative way to the interactions between animal and plants that happens in the dispersive cycle of the species and, therefore this represents a threat for the persistence of populations of Ziziphus lotus on the semiarid southeast.