Browsing by Subject "Ambiente semiárido"

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    Biomasa e índice de área foliar de Rosmarinus officinalis l. en matorral semiarido (Cuenca de Mula, Murcia)
    (Murcia: Universidad de Murcia, Servicio de Publicaciones, 1996) Martínez Fernández, Julia; Martínez Fernández, José; Romero Díaz, María Asunción; López Bermúdez, Francisco; Belmonte Serrato, Francisco; Facultad de Biología
    Se han estudiado diversos parámetros (biomasa e índice de área foliar) de Rosmarinus officinalis L., una de las especies más representativas del matorral mediterráneo, en el Campo Experimental de El Ardal (Cuenca de Mula, Murcia) dentro del marco del Proyecto MEDALUS (Mediterranean Desertification and Land Use), de la Comunidad Europea. Se han establecido relaciones alométricas entre la biomasa y el biovolumen que, posteriormente, han sido utilizadas en la estimación de la biomasa media del matorral. Se ha calculado el índice foliar a partir de las relaciones peso/área foliar y peso foliar/peso total. Los resultados (836.2 g.m-2 de biomasa) muestran valores alejados del rango general aportado para otros matorrales semiáridos, hecho que podría estar parcialmente explicado por la existencia de diversos mecanismos de compensación hídrica.
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    Seed predation by ants in south-eastern Spain (Desierto de Tabernas, Almería)
    (Murcia: Universidad de Murcia, Servicio de Publicaciones, 2002) Hensen, Isabell; Sin departamento asociado; Facultad de Biología
    Seed predation by ants was studied in the Tabernas Desert (Province of Almería, south-eastern Spain). Eight different species of harvester ants were found collecting seeds in single or foraging trails. Six of them feed mainly or exclusively on seeds. The most important predators are polyphagous Messor ants collecting all available seed types from the soil surface as well as directly from the mother plant. Predation of seeds was confirmed for 41 plant species. Their seed masses vary between 0.08 – 95.9 mg. Resource partitioning according to seed size was not observed, indicating that coexistence of ant species may be facilitated by different foraging strategies. To estimate the influence of seed predation on the vegetation structure, the number of collecting runs per colony per day and composition of food items brought in were determined for Messor bouvieri and M. timidus in a Stipa tenacissima dominated grassland. Collecting-activity correlates strongly with soil temperature. The major part of their diet consists of seeds of Helianthemum almeriense and Launaea lanifera. Both Messor species are very similar with respect to worker size range, size of collected seeds, and foraging strategy, which results in a high degree of dietary overlap