PS 83-225
Using seed dispersal networks to assess species importance in tropical restored sites
Human activities in natural environments often lead to the loss of habitats and biodiversity. Ecological restoration is an strategy to rebuild impacted ecosystems and degraded populations aiming at the reconstruction of complex ecological processes. An important ecological process to be restored is seed dispersal. To know which are the plant and seed disperser species that should be used to maximize restoration efforts, we used a network approach to highlight the plants and frugivorous birds that most often interact inthree restored areas planted 15, 25 and 57 years ago with a high-diversity of plant species in the Atlantic Forest, southeast Brazil. From 2011 to 2012 we sampled feces collected from mist-netted birds and made 290 hours of direct observations on fruiting plants to construct seed dispersal networks for each study area. We merged all three networks in a big one to identify which are the most important species in terms of interaction strength and species strength. Interaction strength quantifies the relative importance of a frugivore for a particular plant-species and vice-versa. Species strength is the sum of interaction strength values of a frugivore on all plants or sum of interaction strength values of a plant species on all frugivores.
Results/Conclusions
We recorded 35 frugivorous birds feeding on 27 plant species in 648 interactions. Species strength of frugivores on plants ranged from 6.92 to 0.01. Bird species with the strongest impact were Thraupis sayaca (6.92), Turdus leucomelas (5.38), Ramphocelus carbo (3.70) and Pitangus sulphuratus(2.58). All the other bird species together amounted to 8.43. All frugivores were generalists, which mean that they use other resources besides fruits (e.g. artrhopods, nectar). These bird species are abundant in the landscape and may easily colonize the restored sites. Species strength of plants on frugivores ranges from 7.94 to 0.01. Among the most important plant species we found generalist plants (i.e. with small fruits and abundant fructification): Cytharexylum myrianthum (7.94), Cecropia glaziovii (6.97), Myrsine umbellata (3.37), Callicarpa reevesii (2.49), Miconia c.f. cinnamomifolia (2.49), Melia azedarach (1.58). All the other plant species together summed 8.81. These plant species should be strongly recommended for planting to enhance the availability of fruits and attract seed dispersers. Nevertheless, two of these plant species (C. reversii and M. azedarach) are aliens and recommendation for planting should be examined with caution. Our results demonstrated that generalist species are the most important to seed dispersal networks in restored sites in tropical forests.