Abstract
Numerous organisms depend on the physical structure of their habitats, but incorporating such information into ecological niche analyses has been limited by the lack of adequate data over broad spatial extents. The increasing availability of high‐resolution measurements from country‐wide airborne laser scanning (ALS) surveys – a light detection and ranging (LiDAR) technology – now provides unprecedented opportunities for characterizing habitat structure. Here, we use country‐wide ALS data in combination with presence–absence observations of birds from a national monitoring scheme in the Netherlands to quantify niche filling, niche overlap and niche separation of three closely‐related wetland birds (great reed warbler, Eurasian reed warbler and Savi's warbler). We developed a workflow to derive LiDAR metrics capturing different aspects of vertical and horizontal vegetation structure and used a principal component analysis (PCA), niche equivalency and niche similarity tests to analyse the fine‐scale breeding habitat niches of these warbler species in the Netherlands. The widespread Eurasian reed warbler almost completely filled the available wetland habitat space (93%) whereas the two other species showed considerably less niche filling (64% and 74%, respectively). Substantial niche overlap occurred among all species, but each species occupied a distinct part of the habitat space. The great reed warbler mainly occurred in tall and vertically complex wetland vegetation and was absent in areas with large proportions of reedbeds. The Eurasian reed warbler occupied all parts of the wetland habitat space, whereas the Savi's warbler mainly occurred in large homogenous reedbeds with low vegetation height. Our results demonstrate that broad‐scale ecological niche analyses can incorporate the fine‐scale 3D habitat preference of species with unprecedented detail (e.g. 10 m resolution), and thus go much beyond quantifying the climate niche and 2D habitat information from land cover maps. This is important to identify habitat features and priorities for biodiversity conservation in wetlands and other habitats.
Highlights
The quantification of the ecological niche is of fundamental importance for ecology, biogeography and conservation (Grinnell 1917, Hutchinson 1957, Schurr et al 2012)
We focus on the great reed warbler Acrocephalus arundinaceus, the Eurasian reed warbler Acrocephalus scirpaceus and the Savi’s warbler Locustella luscinioides and derive high resolution (10 m) light detection and ranging (LiDAR) metrics to test for niche overlap using niche similarity and niche equivalency tests (Warren et al 2008, Di Cola et al 2017)
principal component analysis (PCA) 1 was mainly characterized by LiDAR metrics capturing the vertical structure of vegetation around bird observation points (10 m resolution), foliage height diversity (VV_FHD), vegetation density between 0 and 1 meters (VD_0_1) and vegetation height (VV_p95) (Fig. 2d, variable loadings in Supporting information)
Summary
The quantification of the ecological niche is of fundamental importance for ecology, biogeography and conservation (Grinnell 1917, Hutchinson 1957, Schurr et al 2012). The rapid development of ecological niche models (Guisan and Thuiller 2005, Soberón and Nakamura 2009, Araújo et al 2019) and new statistical frameworks for quantitative ecological niche comparisons (Brown and Carnaval 2019) facilitate studies of ecological niche separation in unprecedented detail, both in geographical (Warren et al 2008) and environmental space (Broennimann et al 2012). Such methods allow us to assess whether the ecological niches of two species are equivalent or whether they are more similar than expected by chance given a background environment (Warren et al 2008, Broennimann et al 2012, Brown and Carnaval 2019). Most broad-scale niche studies focus on characterizing the climatic niche whereas niche aspects related to habitat structure have received less attention
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
