Changes in the bird communities of Nothofagus forests in a long-term plot in Tierra del Fuego

J BENITEZ; MV LENCINAS; JE CHAVES; MC DE CRUZ; G MARTÍNEZ PASTUR

Austral Ecology

John Wiley and Sons Inc

Año: 2024 vol. 49

Long-termstudies have proven to be important to characterize animal communitiesand analyse the ecological responses to climate and environmentalchanges. These studies are necessary to determine the natural communityvariability (e.g., richness and density) to develop better conservation strategiesto face climate changes. Here, we analysed the natural changes in thestructure and functional traits of bird communities over 13 consecutive years(2010–2022) and determined the number of years of sampling needed to obtaina good estimation of the community structure variables in deciduous highlatitude Nothofagus forests. Using point counts, we studied closed (80% of canopycover) and open (40% of canopy cover) forests inside the Tierra del FuegoNational Park. Species richness, density, biomass, and functional traits (migratorystatus, trophic groups, nest type, and feeding strata) were analysed usinggeneralized linear models with forest type (closed and open) and year (2010–2022) as the main factors, while the standard error (SE) of sampling obtainedfrom one to 12 sampling years was compared. Richness was significantly higherin open forests (p < 0.01), while density and biomass were higher in closed forests.Additionally, density and biomass significantly varied among years in bothforest types (e.g., lower density in 2013, 2014 and 2015, and higher in 2019). Thedensity of birds for some functional traits also varied among years and foresttypes (e.g., higher values of cavity nesters in closed forests during 2019). Five tosix years of sampling were needed to have an acceptable estimation of richness(20% SE), between 10 and 12 years for density, and >12 years for biomass. Thisstudy highlights the importance of long-termstudies to visualize natural variationsin undisturbed habitats along time.