Abstract
Land use change modifies the environment at multiple spatial scales, and is a main driver of species declines and deterioration of ecosystem services. However, most of the research on the effects of land use change has focused on taxonomic diversity, while functional diversity, an important predictor of ecosystem services, is often neglected. We explored how local and landscape scale characteristics influence functional and taxonomic diversity of hummingbirds in the Andes Mountains in southern Ecuador. Data was collected in six landscapes along a land use gradient, from an almost intact landscape to one dominated by cattle pastures. We used point counts to sample hummingbirds from 2011 to 2012 to assessed how local factors (i.e., vegetation structure, flowering plants richness, nectar availability) and landscape factors (i.e., landscape heterogeneity, native vegetation cover) influenced taxonomic and functional diversity. Then, we analyzed environment – trait relationships (RLQ test) to explore how different hummingbird functional traits influenced species responses to these factors. Taxonomic and functional diversity of hummingbirds were positively associated with landscape heterogeneity but only functional diversity was positively related to native vegetation coverage. We found a weak response of taxonomic and functional diversity to land use change at the local scale. Environment‐trait associations showed that body mass of hummingbirds likely influenced species sensitivity to land use change. In conclusion, landscape heterogeneity created by land use change can positively influence hummingbird taxonomic and functional diversity; however, a reduction of native vegetation cover could decrease functional diversity. Given that functional diversity can mediate ecosystem services, the conservation of native vegetation cover could play a key role in the maintenance of hummingbird pollination services in the tropical Andes. Moreover, there are particular functional traits, such as body mass, that increase a species sensitivity to land use change.
Highlights
Land use change is one of the most important drivers of species loss and degradation of ecosystem services (Cardinale et al, 2012; Sala et al, 2000)
When species were plotted in functional traits space, we found that species positively associated with characteristics of less altered landscape unit (LU) were E. ensifera, P. cyanopterus, C. iris, and A. cupripennis (Figure 2), while species that likely preferred characteristics of more altered LUs included M. tyrianthina and L. nuna
Plotting species within functional traits space revealed that species associated with plots with abundant shrubs and high resource availability included P. cyanopterus, A. cupripennis, and C. iris, while species associated with plots with the presence of large trees and low sugar availability included L. nuna and M. tyrianthina (Figure 3)
Summary
Land use change is one of the most important drivers of species loss and degradation of ecosystem services (Cardinale et al, 2012; Sala et al, 2000). We evaluate how taxonomic and functional diversities of hummingbirds are affected by ongoing land use change in the tropical Andes. Hummingbirds are suitable for the study of the effects of land use change on biodiversity They are among the most species- rich and abundant groups of birds in the tropical Andes (Rahbek & Graves, 2000). While hummingbird taxonomic diversity is often considered relatively insensitive to land use change (Renjifo, 2001; Stouffer & Bierregaard, 1995), a recent study by Hadley, Frey, Robinson, and Betts (2017), in the lowlands of Costa Rica, found that species richness, relative abundance, and species with specialized morphologies can be sensitive to habitat loss. Using extensive knowledge of functional traits in hummingbirds, we developed a set of predictions for how these traits may influence a hummingbird’s response to land use change (Table 1) and tested those predictions by performing an analysis of environment–trait relationships
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