Determinants of bird species richness: role of climate and vegetation structure at a regional scale

Abstract

We examined the respective roles of climate and vegetation structure on geographical variation in bird species richness. The Province of Buenos Aires (central-eastern Argentina) was divided into 146 squares of 50 km on a side. For each square we evaluated the number of bird species, the value of thirteen climatic variables, and the value of a vegetation strata index. The climatic matrix was analyzed by Principal Component Analysis (PCA), and the first factors resulting from PCA were considered as multifactorial climatic gradients. Simple and Partial Correlation Analysis among bird species richness, vegetation strata, and the first two factors derived from PCA (65% of total variation) indicated that bird richness distribution was determined by the availability of vegetation strata, associated with different vegetation types that, at the same time, were influenced by the climatic conditions summarized in the first climatic factor (a gradient of precipitation, relative humidity, annual termical amplitude, and frost occurrence). This relationships reflect the complexity of factors that can act directly as well as indirectly on the geographical patterns in species richness. Also, we evaluated the importance of study scale comparing our results with previous studies at macrogeographic and local scales, found out that the vegetation structure was the principal determinant of bird species richness at this three geographical scales.

Avian species distribution along elevation at Doon Valley (foot hills of western Himalayas), Uttarakhand, and its association with vegetation structure

“…Generally, the available knowledge about the avian species distribution pattern along an elevation is not clear approximately 49% of studies show peaked at mid elevation or humped shape patterns, 20% decrease and 24% high richness at low elevation respectively (Rahbek 1995(Rahbek , 2005. In general, forest provides a wide range of variation in bird habitat (Fuller 1995) and the important factors of this variation include vegetation structure (Cueto and de Casenave 1999;Holmes and Sherry 2001). The Indian Himalayan range is well recognized for its biological diversity and ecological value (Bhattacharya and Sathyakumar 2007).…”

Environmental key factors and their thresholds for the avifauna of temperate montane forests

“…The change in the bird species composition at various successional stages has also been investigated in Central Europe (Glutz von Blotzheim, 2001;Christen, 2003;Scherzinger, 2006). In general, interrelated effects of climate, habitat physiognomy (mainly vegetation cover and diversity of stratification: Rov, 1975;Cueto and de Casenave, 1999), competitive interactions, food resources, wintering habits and biogeographic origin of the avifaunas have been considered to be the most important factors determining the avian species composition and niche structures in a variety of montane habitats (Sabo and Holmes, 1983).…”

Temporal and spatial variation of richness and abundance of the community of birds in the Pantanal wetlands of Nhecolândia (Mato Grosso do Sul, Brazil)

“…The spatial distribution of the animal diversity has also been explained in climate and vegetational structure (Cueto & Casenave, 1999;Veech & Crist, 2007). According to Farley, Ellis, Stuart & Scott (2004) habitat variability is a determinant part of the structure and dynamics of a community of birds, because most of the species are closely related to specific habitats.…”