The Influence of Vegetation Height Heterogeneity on Forest and Woodland Bird Species Richness across the United States

Abstract

Avian diversity is under increasing pressures. It is thus critical to understand the ecological variables that contribute to large scale spatial distribution of avian species diversity. Traditionally, studies have relied primarily on two-dimensional habitat structure to model broad scale species richness. Vegetation vertical structure is increasingly used at local scales. However, the spatial arrangement of vegetation height has never been taken into consideration. Our goal was to examine the efficacies of three-dimensional forest structure, particularly the spatial heterogeneity of vegetation height in improving avian richness models across forested ecoregions in the U.S. We developed novel habitat metrics to characterize the spatial arrangement of vegetation height using the National Biomass and Carbon Dataset for the year 2000 (NBCD). The height-structured metrics were compared with other habitat metrics for statistical association with richness of three forest breeding bird guilds across Breeding Bird Survey (BBS) routes: a broadly grouped woodland guild, and two forest breeding guilds with preferences for forest edge and for interior forest. Parametric and non-parametric models were built to examine the improvement of predictability. Height-structured metrics had the strongest associations with species richness, yielding improved predictive ability for the woodland guild richness models (r2 = ∼0.53 for the parametric models, 0.63 the non-parametric models) and the forest edge guild models (r2 = ∼0.34 for the parametric models, 0.47 the non-parametric models). All but one of the linear models incorporating height-structured metrics showed significantly higher adjusted-r2 values than their counterparts without additional metrics. The interior forest guild richness showed a consistent low association with height-structured metrics. Our results suggest that height heterogeneity, beyond canopy height alone, supplements habitat characterization and richness models of forest bird species. The metrics and models derived in this study demonstrate practical examples of utilizing three-dimensional vegetation data for improved characterization of spatial patterns in species richness.

Do birds see the forest for the trees? Scale-dependent effects of tree diversity on avian predation of artificial larvae

“…Birds, in particular, have received little attention even though they are widely considered to be important control agents of insect pests in forest stands (Mäntylä et al 2011;Bereczki et al 2012) and can deliver a key ecosystem service (Whelan et al 2015). In addition, the diversity and abundance of avian predators has not only been shown to respond to increased structural and floristic diversity (MacArthur and MacArthur 1961;Bereczki et al 2014;Huang et al 2014), but also vary with densities of individual tree species (Wiens and Rotenberry 1981;Mason 1997). Nevertheless, very few studies have examined the effects of tree diversity on avian predation in forest ecosystems (Giffard et al 2012;Poch and Simonetti 2013;Giffard et al 2013;Bereczki et al 2014) and, of these studies, none have directly tested the effects of increasing tree species richness or explored the effects of tree species composition and individual tree species densities on bird predator effectiveness.…”

Can Airborne Laser Scanning (ALS) and Forest Estimates Derived from Satellite Images Be Used to Predict Abundance and Species Richness of Birds and Beetles in Boreal Forest?

“…ALS data can also be combined with satellite images [51] or aerial images [52,53], providing a better description of the tree species composition. To further improve the analysis, the raw remotely-sensed data can be replaced with forest estimates from a combination of remotely-sensed data and forest field inventories [54][55][56][57].…”

Patterns and causes of covariation in bird and butterfly community structure

“…The principal of surrogacy was therefore partially supported, demonstrating that fine-scale variation in bird and butterfly communities occurs not as a result of large-scale latitudinal gradients, or variation in land cover, but probably through some common effects of fine-scale variation in habitat quality or unmeasured habitat heterogeneity that similarly affect both bird and butterfly community richness and diversity. A possible candidate for this variation may be fine-scale variation in vegetation structure and heterogeneity within habitat-types (Atauri and de Lucio 2001;Tews et al 2004;Huang et al 2014). In contrast to richness and diversity, estimates of evenness were uncorrelated between birds and butterflies, whilst the correlation with community specialisation became non-significant once the effect of latitude was accounted for.…”