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Context Supplemental feeding of large mammalian herbivores is a common management tool mainly aimed at promoting healthy populations and at increasing productivity and trophy sizes. Such management measure may indirectly affect herbivore effects on plant communities through altered foraging patterns. The quantification of the ecological effects of large herbivore management is important for designing holistic management and conservation programs. Aims Here we aimed at quantifying the ecological effects of supplemental feeding of Iberian red deer, Cervus elaphus hispanicus, on the composition of and on the browsing effects on Mediterranean woody plant community. Methods An experiment was set up in a hunting rangeland located in central Spain, where female deer were kept in enclosures with either exclusive access to natural forages or with additional ad libitum access to a nutritionally rich concentrate. The experiment also included a control area where deer were absent. Key results We observed significant differences in browsing impacts among the supplemented, non-supplemented and control areas, and such effect varied for the different plant species. Plant species which nutritional content complemented that of fodder were more highly consumed, for instance, Erica spp., which digestible fibre content is higher and N content lower than that of provided fodder. The presence of deer and the concentrate supplied, instead, did not influence the relative abundances of shrub species. Conclusions Artificial supplemental feeding provided to ungulates led to increased browsing on plant species which nutritional composition complemented that of the supplement provided. Implications So as to alleviate herbivory impact on all shrubs, we suggest that composition of supplemental feeding should adjust both to the natural forage availability and quality and to ungulate requirements across seasons.

We report evidence of hierarchical resource selection by large herbivores and plant neighbouring effects in a Mediterranean ecosystem. Plant palatability was assessed according to herbivore foraging decisions. We hypothesize that under natural conditions large herbivores follow a hierarchical foraging pattern, starting at the landscape scale, and then selecting patches and individual plants. A between- and within-patch selection study was carried out in an area formed by scrubland and pasture patches, connected by habitat edges. With regard to between-patch selection, quality-dependent resource selection is reported: herbivores mainly consume pasture in spring and woody plants in winter. Within-patch selection was also observed in scrub habitats, influenced by season, relative patch palatability and edge effect. We defined a Proximity Index (PI) between palatable and unpalatable plants, which allowed verification of neighbouring effects. In spring, when the preferred food resource (i.e. herbs) is abundant, we observed that in habitat edges large herbivores basically select the relatively scarce palatable shrubs, whereas inside scrubland, unpalatable shrub consumption was related to increasing PI. In winter, a very different picture was observed; there was low consumption of palatable species surrounded by unpalatable species in habitat edges, where the latter were more abundant. These outcomes could be explained though different plant associations described in the literature. We conclude that optimal foraging theory provides a conceptual framework behind the observed interactions between plants and large herbivores in Mediterranean ecosystems.

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