Variable relationships between trait diversity and avian ecological functions in agroecosystems [Dataset]

dataset: SeedDispersal_data_Pastures.csv: It contains data of the resource and forest cover availability, FDis and MPD standardized values for each frugivorous local assemblage, frugivorous bird abundances, and the dispersed seeds by birds, in different sampling plots in woodland pastures. Below we describe the contents of each column: plot_code: code for plot identity. year: sampling year. id_station: code for seed-trap identity. disp_seeds_m2: dispersed seeds/m2 Forest_cover: forest cover availability in each plot. Fruit_abundance: resource availability in each plot. FDis: Trait-based functional diversity estimated as the standardized Functional Dispersion in each local assemblage. Frug_abundance: abundance of all present frugivorous birds per plot. MPD: Phylogenetic Diversity estimated as the standardized Mean Pairwise Distance in each local assemblage.

dataset: Insectivory_data_Pastures.csv: It contains data of the resource and forest cover availability, FDis and MPD standardized values for each insectivorous local assemblage, insectivorous bird abundances, and the dispersed seeds by frugivorous birds, in different sampling plots in woodland pastures. Below we describe the contents of each column: plot_code: code for plot identity year: sampling year tree_identity: code for focal tree identity. Attacked_success: pecked caterpillar. Intact_failure: intact caterpillar. n_models: number of caterpillar models placed on each focal tree. Forest_cover: forest cover availability in each plot. arthropod_g: resource availability in each plot. FDis: Trait-based functional diversity estimated as the standardized Functional Dispersion in each local assemblage. FI_bird_abundance: abundance of all forest insectivorous birds per plot. MPD: Phylogenetic Diversity estimated as the standardized Mean Pairwise Distance in each local assemblage.

dataset: Insectivory_data_Orchards.csv: It contains data of the resource and forest cover availability, FDis and MPD standardized values for each insectivorous local assemblage, insectivorous bird abundance, and the dispersed seeds by frugivorous birds, in different sampling plots in apple orchards. Below we describe the contents of each column: plot_code: code for plot identity year: sampling year tree_identity: code for focal tree identity Attacked_success: pecked caterpillar Intact_failure: intact caterpillar n_models: number of caterpillar models placed on each focal tree Forest_cover: forest cover availability in each plot. arthropod_g: resource availability in each plot. FDis: Trait-based functional diversity estimated as the standardized Functional Dispersion in each local assemblage. FI_bird_abundance: abundance of all forest insectivorous birds per plot. MPD: Phylogenetic Diversity estimated as the standardized Mean Pairwise Distance in each local assemblage.

1) The diversity of traits within animal assemblages has been shown to affect the magnitude of animal-provided ecological functions. However, little is known about how consistent trait diversity effects are across ecological functions and ecosystems. More importantly, the importance of trait diversity in driving ecosystem functioning, relative to other components of biodiversity, has rarely been assessed. It also remains unclear how environmental gradients filter trait diversity and, ultimately, modulate ecological functions. 2) Here we test how different biodiversity components (i.e., trait diversity, phylogenetic diversity and abundance) affect the magnitude of avian seed dispersal and insect predation along large environmental gradients. We sampled frugivorous and insectivorous birds and their ecological functions across gradients of forest cover and fruit and insect abundances in woodland pastures and apple orchards in Northern Spain. We measured 6 morphological traits and compiled phylogenetic information on 43 bird species. We used Structural Equation Models to disentangle the effects of environmental gradients and biodiversity components on ecological functions. 3) We found that different avian functions in the same agroecosystem were controlled by different biodiversity components. While seed dispersal was positively driven by bird abundance in woodland pastures, insect predation responded positively to trait and phylogenetic diversity. The positive effects of trait diversity on insect predation were, on the other hand, consistent across woodland pastures and apple orchards. 4) Our results also pinpointed forest cover and resource availability as filters of the different components of avian diversity, suggesting that environmental gradients condition the effects of biodiversity on avian ecological functions. 5) Our findings reveal variable effects of trait diversity on two different avian ecological functions, but consistent effects on the same function across agroecosystems. Consolidating the generalities of trait diversity effects will require further multi-function studies, as well as a unifying framework for animal-driven functions that integrates the causal links between environmental gradients, the different biodiversity components, and ecological functions.

MinECo/FEDER, Award: CGL2015-68963-C2-2-R

MinECo/FEDER, Award: BES-2016-078260

Fundación BBVA, Award: 044-2019 ClaveSER

Peer reviewed