Long-term dynamic of nestedness in bird assemblages inhabiting fragmented landscapes

Abstract

Context Nestedness is a common pattern of species assemblages in fragmented landscapes. The spatial pattern and ecological drivers of nested communities have been widely explored, but few studies investigated their long-term variability. Objectives To investigate the variability of nestedness and species-specific fragment occupancy of forest birds in a fragmented landscape affected by environmental changes over 16 years. Methods Data were obtained from the Monitoring Program of Breeding Birds in Lombardy (northern Italy). For two study periods (1997–2001, 2013–2017), we tested for overall nestedness and for sites and species nestedness independently using the NODF metric. We tested for nestedness drivers (variable selection on multiple linear regression models) and evaluated the effect of species ecological traits on fragment occupancy changes (variable selection on multiple linear regression model). Results The community showed a significant nestedness driven by both selective extinction and selective colonization in both study periods. Sites nestedness was significant in the second study period only. Over 16 years the effect of distance from source areas was completely lost and only local isolation conditions drove selective colonization in the second study period. Between the two study periods, we discovered a general occupancy decrease of interior species and a significant occupancy increase of generalist species characterized by large size and large minimum area requirement. Conclusions Nestedness drivers of the investigated community significantly varied over time probably because of both environmental and demographic changes. Long-term studies are crucial to explore spatial pattern changes and to address management strategies for species conservation in fragmented landscapes.

Do functional and phylogenetic nestedness follow the same mechanisms as taxonomic nestedness? Evidence from amphibians in the largest archipelago of China

“…Thus, the bias brought by inventory completeness is actually weak (Colwell & Elsensohn, 2014). We are also aware that the imperfect detection of rare species may bias estimates of species richness (Dondina et al, 2022; Wang et al, 2015). Indeed, some species showed lower abundance on islands (e.g.…”

“…A study in forest fragments further suggested that the ordered loss of traits from specific habitats induced the functional nestedness of frog communities (Almeida‐Gomes et al, 2019). However, most of these views were based on short‐term responses of species from habitat islands, and less is known about the functional and phylogenetic adaptation of amphibians to long‐term isolated insular systems (but see Dondina et al, 2022).…”

New Evidence on the Linkage of Population Trends and Species Traits to Long-Term Niche Changes

“…Dispersal ratio, a surrogate of species mobility and dispersal ability [89,90], showed that species with higher dispersal ability would not tend to expand the niche, but findings were inconclusive in respect to unfilling. We also have to consider that the dispersal ratio could be an inappropriate indicator of the dispersal ability [64,126], as well as that habitat configuration and landscape connectivity significantly affect the dispersal process [127], leading to idiosyncratic responses between species. Regarding the degree of species specialization (Dim2 of PCA), niche metrics were not linked with it, although a weak signal showed that specialist birds tend to retain their niche more than generalist ones.…”

Selective extinction and habitat nestedness are the main drivers of lizard nestedness in the Zhoushan Archipelago

“…Our study differs from previous nestedness studies in several ways. First, although nestedness has been documented for a variety of taxa ( Wright et al 1998 ; Watling and Donnelly 2006 ; Dondina et al 2022 ), it is rarely examined in lizard assemblages from oceanic archipelago systems ( Perry et al 1998 ). Our study on lizards thus fills in a significant gap and contributes to the ecological generality of nestedness across a wide range of taxa.…”