How are riparian plants distributed along the riverbank topographic gradient in Mediterranean rivers? Application to minimally altered river stretches in Southern Spain.

Species structure and composition in Mediterranean riparian forests are determined by hydrological features, longitudinal zonation, and riverbank topography. This study assesses the distribution of four native riparian plants along the riverbank topographic gradient in three river stretches in southern Spain, with special emphasis on the occupation of adult and young feet of each species. The studied stretches suffered minimal human disturbances, displayed semi-arid conditions, and had wide riparian areas to allow the development of the target species: black alder (Alnus glutinosa), salvia leaf willow (Salix salviifolia), narrow-leafed ash (Fraxinus angustifolia), and oleander (Nerium oleander). Thalweg height was used to define the riverbank topographic gradient. The results showed a preferential zone for black alder and salvia leaf willow in the range of 0-150 cm from the channel thalweg, with adult alders and willows being more common between 51 and 150 cm and young alders being more common under 50 cm. Conversely, narrow-leafed ash and oleander were much more frequent, and showed greater development, in the ranges of 151-200 cm and 201-250 cm, respectively, whereas the young feet of both species covered the entire topographic range. Adult feet of the four species were spatially segregated along the riverbank topographic gradient, indicating their differential ability to cope with water stress from the non-tolerant alders and willows to more tolerant narrow-leafed ash trees and oleanders. Young feet, however, showed a strategy more closely linked to the initial availability of colonisation sites within riparian areas to the dispersion strategy of each species and to the distribution of adult feet. In Mediterranean areas, where riparian management has traditionally faced great challenges, the incorporation of species preferences along riverbank gradients could improve the performance of restoration projects.

Building wood debris piles benefits avian seed dispersers in burned and logged Mediterranean pine forests

Salvage logging is a common practice carried out in burned forests worldwide, and intended to mitigate the economic losses caused by wildfires. Logging implies an additional disturbance occurring shortly after fire, although its ecological effects can be somewhat mitigated by leaving wood debris on site. The composition of the bird community and its capacity to provide ecosystem services such as seed dispersal offleshy-fruited plants have been shown to be affected by postfire logging. We assessedthe effects of the habitat structure resulting from different postfire management practices on the bird community, in three burned pine forests in Catalonia (western Mediterranean). For this purpose, we focused on the group of species that is responsible for seed dispersal, a process which takes place primarily during the winter in theMediterranean basin. In addition, we assessed microhabitat selection by seed disperser birds in such environments in relation to management practices. Our results showed a significant, positive relationship between the density of wood debris piles and the abundance of seed disperser birds. Furthermore, such piles were the preferredmicrohabitat of these species. This reveals an important effect of forest management on seed disperser birds, which is likely to affect the dynamics of bird-dependent seed dispersal. Thus, building wood debris piles can be a useful practice for the conservation of both the species and their ecosystem services, while also being compatible with timber harvesting