Trait‐associated loss of frugivores in fragmented forest does not affect seed removal rates

Abstract

Summary1. Seed dispersal by frugivorous animals forms the basis for regeneration of numerous plant species. Habitat fragmentation has been found to be one major factor perturbing frugivore communities and dependent plant species. Yet, community-wide consequences of fragmentation for both frugivore and plant communities are still hardly understood. 2. Here, we studied the effects of habitat fragmentation on the seed removal by frugivorous birds and mammals from nine fleshy-fruited plant species in Białowie_ za Forest (Eastern Poland). This last relict of old-growth lowland forest in Europe poses an exceptional reference site for studying the impact of habitat fragmentation on seed dispersal processes in temperate forest ecosystems. 3. In particular, (i) we tested for associations between forest fragmentation and response traits of frugivores, that is forest specialization and body mass; (ii) we studied the relationship between frugivore response and effect traits, that is centrality (number of consumed plant species) and interaction type (mutualistic vs. antagonistic); and (iii) we assessed the feedback of fragmentation-induced changes on plant-frugivore interactions and seed removal rates. 4. We found that fragmentation led to shifts in the frugivore community, associated with the response traits forest specialization and body mass, with fewer forest specialists and large-bodied frugivores in fragmented than in continuous forests. However, forest generalists and small-bodied frugivores were more central in the plant-frugivore associations than forest specialists and largebodied frugivores. Therefore, the loss of vulnerable species did not result in reduced seed removal rates in fragmented compared with continuous forest. 5. Synthesis. These results indicate that seed removal may be relatively robust in spite of shifts in the frugivore community in forest fragments. The correlation between response and effect traits of frugivores highlights the importance of forest generalists and small-bodied frugivores for maintaining dispersal processes in fragmented forests in temperate regions. Yet, future studies should aim at quantifying the consequences of seed disperser loss on other aspects of dispersal, such as long-distance dispersal, spatial patterns of seed deposition, seed germination and plant regeneration.

Bird functional traits affect seed dispersal patterns of China’s endangered trees across different disturbed habitats

“…2), which could be explained by both bird and plant traits (Farwig et al 2017). For the bird perspective, it has been shown that medium-sized birds are not as sensitive to disturbance as large-bodied birds (Moore and Swihart 2007;Breitbach et al 2010), as the remaining forests still provide adequate shelter and food for the persistence of medium-sized birds in disturbed habitats.…”

“…For the bird perspective, it has been shown that medium-sized birds are not as sensitive to disturbance as large-bodied birds (Moore and Swihart 2007;Breitbach et al 2010), as the remaining forests still provide adequate shelter and food for the persistence of medium-sized birds in disturbed habitats. For the plant perspective, plant traits of T. chinensis also determined the persistence of birds in disturbed habitats, thus affecting the foraging behaviour of birds (Farwig et al 2017;Muñoz et al 2017). Crop size, fruit size, and height of T. chinensis could be good advertisements that attract birds (crop size: 4000 per mother tree; fruit weight: 7 g; height: 25-45 m) (Jordano and Schupp 2000;Martinez et al 2008;Herrera and García 2009;Li et al 2017).…”

“…In various disturbed habitats, the seed dispersal pattern of frugivorous birds directly reflects their functional traits, especially their morphological traits (Larsen et al 2005;Suding et al 2008;Schupp et al 2010;Bregman et al 2016;Farwig et al 2017). As many ecologists predicted, the body size of birds can be used to estimate the ecological role of birds in seed removal and can affect the degree of species-specific interactions in seed-dispersal distance (Perez-Méndez et al 2015;Bregman et al 2016; Open Access Avian Research *Correspondence: lining196@126.com 1 Institute of Applied Ecology, Nanjing Xiaozhuang University, Nanjing 211171, China Full list of author information is available at the end of the article Muñoz et al 2017).…”

“…foraging behaviour, flight behaviour, etc.) (Bregman et al 2016;Farwig et al 2017). Owing to the inherent difficulty of monitoring multiple bird functional traits in different disturbed habitats, empirical evidence supporting the extent of the role of bird functional traits in seed dispersal mutualism remains limited.…”

Complementary Effects of Species Abundances and Ecological Neighborhood on the Occurrence of Fruit-Frugivore Interactions

“…Therefore, the fact that generalist species could reorganize their interactions by replacing their partners suggested that species in our generalized plant-frugivore assemblage were efficient when tracking fruit resources and showed strong context dependency despite the interannual spatial variability Chamberlain et al, 2014). Since seed removal has been shown to not be strongly affected by possible shifts in the frugivory community (Farwig et al, 2017), temporal inconsistency in the spatial patterns of interaction might have long-term effects on seed-dispersal processes, especially in such degraded and fragmented systems. Although denser seed rain is expected in areas concentrating pairwise interactions, as suggested by the typically higher density of dispersed seeds under fruiting canopies (García et al, 2005b;Herrera and García, 2010;Carlo et al, 2013), this temporal and spatial dynamism might be relevant for diluting density-dependent seed mortality, favoring genetic exchange, interspecific seed transfer (García et al, 2007) and promoting seed deposition and forest regeneration in open areas (Martínez and García, 2015b).…”