Effectiveness of seed dispersal by foxes in areas with different human disturbances in southern Chile

TL;DR

Foxes in southern Chile help spread seeds of both native and exotic plants, but their effectiveness depends on landscape disturbance and plant species.

Contribution

The study reveals how foxes' seed dispersal effectiveness varies with landscape disturbance and plant species, impacting forest regeneration.

Findings

Native seeds were more common in feces from less disturbed areas, while exotic seeds showed variable patterns.

Germination rates were higher in less disturbed landscapes, but U. molinae thrived in disturbed areas.

Foxes effectively disperse seeds of native and exotic species, influencing forest regeneration and exotic spread.

Abstract

Frugivorous mammals play a key role in forest regeneration by dispersing seeds yet their effectiveness can vary with landscape disturbance and the native or exotic status of the plant species. In the temperate forests of southern Chile, we evaluated the seed dispersal efficiency (SDE) of foxes (Lycalopex spp.) for native and exotic fleshy-fruited plants across 10 sites spanning a gradient from less to more disturbed landscapes. SDE was assessed though two components: quantity (frequency of feces containing seeds and number of seeds per plant species) and quality (proportion of viable seeds and their germination success under natural conditions). Between November 2022 and July 2023, we collected 199 fox fecal samples, of which 131 contained seeds. In total, we recovered of 23,012 seeds from three native species (Aristotelia chilensis, Gaultheria mucronata, Ugni molinae) and three exotic species (Prunus spp., Malus sylvestris, Rubus ulmifolius). Native seeds were more frequently found in feces from less disturbed landscapes, whereas exotic species exhibited more variable patterns. Seed viability was generally high and unaffected by landscape type, although germination rates were higher in less disturbed areas. Notably, G. mucronata failed to germinate in more disturbed landscapes despite high viability. Conversely, U. molinae showed significantly greater SDE in more disturbed areas due to higher seed quantity and germination. These findings demonstrate that foxes are effective seed dispersers of both native and exotic species, with their effectiveness shaped by landscape type and plant species. Our results highlight the dual ecological role of generalist frugivores in supporting native plant regeneration while potentially facilitating the spread of exotic species. We recommend that future conservation and restoration efforts consider these dynamics when managing fragmented temperate forests.

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