Positive adjacency effects mediated by seed disperser birds in pine plantations

Abstract

Abstract. This study examines the consequences of adjacent elements for a given patch, through their effects on zoochorous dispersion by frugivorous birds. The case study consists of pine plantations (the focal patch) adjacent to other patches of native vegetation (mixed patches of native forest and shrublands), and/or pine plantations. Our hypothesis is that input of native woody species propagules generated by frugivorous birds within plantations strongly depends on the nature of the surrounding vegetation. To test this hypothesis, we studied frugivorous-bird abundance, seed dispersion, and seedling establishment in nine pine plantation plots in contact with patches of native vegetation. To quantify adjacency arrangement effects, we used the percentage of common border between a patch and each of its adjacent elements. Frugivorous bird occurrence in pine plantations is influenced by the adjacent vegetation: the greater the contact with native vegetation patches, the more abundant were the frugivorous birds within pine plantations. Furthermore, frugivorous birds introduce into plantations the seeds of a large sample of native fleshy-fruited species. The results confirm the hypothesis that zoochorous seed rain is strongly determined by the kind of vegetation surrounding a given plantation. This finding underlines the importance of the composition of the mosaic surrounding plantations and the availability of mobile link species as key landscape features conditioning passive restoration processes.

Patterns of shrub diversity and tree regeneration across topographic and stand-structural gradients in a Mediterranean forest

“…Similarly, fleshy-fruited shrubs are important for avian communities, since two-thirds of the passerine species present in Cazorla mountain range feed on shrub fleshy-fruits over the winter, with fruits of Rosa and Berberis eaten by birds of the genus Turdus in particular (Herrera 1984a(Herrera , 1984b. Although the present study did not aim to analyse the demography of shrub species, results suggest the existence of limited recruitment that could be enhanced by a proper management of vegetation structure (Zamora et al, 2010). This recommendation of proactive management also applies to oak regeneration, if Navahondona is to become a more mixed forest in accordance with the currently established management plans for Cazorla, Segura and Las Villas Natural Park.…”

Predation and aridity slow down the spread of 21-year-old planted woodland islets in restored Mediterranean farmland

“…Key constraints on the speed of regeneration include (1) dispersal limitation because seed sources are remote and dispersal vectors may be rare (Rey Benayas et al 2008a;Pons and Pausas 2007a;Zamora et al 2010;Ramos-Palacios et al 2014); (2) seed predation Pérez-Ramos and Marañón 2008;Gómez and Hódar 2008;Leiva and Fernández 2003); (3) biotic limitation such as competition from established woody vegetation and herbaceous vegetation (Rey Benayas et al 2005;Cuesta et al 2010a), and herbivory Puerta et al 2012); and (4) abiotic limitation such as low water availability, extreme temperatures, poor soil structure and low nutrient availability (Rey Benayas 1998;Cuesta et al 2010b). Intensification of land use has brought remnant areas of natural or semi-natural vegetation into mainstream agriculture and as a result many of such areas have been lost or severely degraded.…”

Pine Stand Density Influences the Regeneration of Acacia saligna Labill. H.L.Wendl. and Native Woody Species in a Mediterranean Coastal Pine Plantation

“…Firstly, it should be noted that A. saligna is able to reduce the soil seed bank of native species over time [61]. Forest ecosystems in the surrounding areas of the Platani reserve are very rare and fragmented; mature woody individuals, therefore, are too few and/or too far away, thus compromising the chance of passive restoration processes via bird communities [73]. Active restoration through direct sowing or planting of native woody species is required [8,27,62].…”

“…Then, as native woody species in the Platani reserve all bear fleshy fruits or acorns, their dissemination strongly depends upon the occurrence of seed dispersers, especially frugivorous birds [73,75,76]. Gómez-Aparicio et al [8] found that 4 km is the maximum seed dispersal distance by Garrulus glandarius L. to enable the effective establishment of Holm oak in Mediterranean contexts.…”