Frugivory on Persea lingue in temperate Chilean forests: interactions between fruit availability and habitat fragmentation across multiple spatial scales

Abstract

Habitat degradation and fragmentation are expected to reduce seed dispersal rates by reducing fruit availability as well as the movement and abundance of frugivores. These deleterious impacts may also interact with each other at different spatial scales, leading to nonlinear effects of fruit abundance on seed dispersal. In this study we assessed whether the degradation and fragmentation of southern Chilean forests had the potential to restrict seed dispersal the lingue (Persea lingue) tree, a fleshy-fruited tree species. Of five frugivore bird species, the austral thrush (Turdus falcklandii) and the fire-eyed diucon (Xolmis pyrope) were the only legitimate seed dispersers as well as being the most abundant species visiting lingue trees. The results showed little or no direct effect of habitat fragmentation on seed dispersal estimates, possibly because the assemblage of frugivore birds was comprised habitat-generalist species. Instead, the number of fruits removed per focal tree exhibited an enhanced response to crop size, but only in the more connected fragments. In the fruit-richer fragment networks, there was an increased fragment-size effect on the proportion of fruits removed in comparison to fruit-poor networks in which the fragment size effect was spurious. We suggest that such nonlinear effects are widespread in fragmented forest regions, resulting from the link between the spatial scales over which frugivores sample resources and the spatial heterogeneity in fruiting resources caused by habitat fragmentation and degradation.

Frugivory of Persea lingue (Lauraceae) and its effect on seed germination in southern Chile

“…Vergara et al 2010). The dominant tree species in the fragments studied were Nothofagus obliqua, Eucryphia cordifolia, Aextoxicon punctatum and Laurelia sempervirens.…”

“…Along the last 25 years, there has been increasing interest into researching the species involved in endozoochory processes in this forest type (Armesto et al 1987, Willson et al 1996, Aizen et al 2002, Amico & Aizen 2005, Vergara et al 2010, Mora & Soto-Gamboa 2011, Salvande et al 2011, Orellana et al 2014. Many of these studies described vertebrates (reptiles, birds and mammals) as dispersers of plant seeds.…”

“…We selected this species to study its interactions with vertebrate animals due to its limited dispersal effectiveness as a consequence of its large sized fruits that can affect its gene movement. Fruits of P. lingue ripe between March and May, after growth for 10 to 14 months (Donoso & Escobar 2006, Vergara et al 2010, and represent one of the few species of the temperate rainforest with ripe fruits in autumn (Riveros & Smith-Ramí rez 1996, Vergara et al 2010. The fleshy fruit of this tree is a drupe, which color varies from violet to shiny black, suggesting bird dispersal mechanism (Armesto & Rozzi 1989, Cousens et al 2008).…”

Phenological synchrony between the austral thrush Turdus falcklandii (Passeriformes: Turdidae) and its food resources within forests and prairies in southern Chile

“…In the study area, the thrush was (Verbenaceae); therefore, the study was based on the phenological monitoring of these species. Previous reports suggest that the fruits of these species form a regular part of the diet of the thrush in the forests of South Chile (Armesto et al 1996;Valdivia and Simonetti 2007;Vergara et al 2010; BustamanteSanchez and Armesto 2012).…”

“…As a result of these studies, it has been determined that the Austral thrush Turdus falcklandii Quoy & Gaimard 1824 is a key species in the dispersion of the seeds for the majority of forest plants with fleshy fruits. Its relevance as a seed disperser lies in numerous factors, such as (i) its large population size (Armesto et al 1987;Armesto et al 1996;Rozzi et al 1996a), (ii) the high frequency with which it eats fruits (Armesto et al 2001;Aizen et al 2002;Amico and Aizen 2005;Salvande et al 2011), (iii) its annual residency (Armesto et al 1987;Willson et al 1996), (iv) its ability to eat fruits with diameters that are larger than the dimensions of its beak, which allows it to eat fruits of a wide range of sizes (Willson et al 1996;Vergara et al 2010), and (v) the scarcity of other frugivorous birds (Armesto et al 1987;Rozzi et al 1996a). …”