Contrasting trait assembly patterns in plant and bird communities along environmental and human‐induced land‐use gradients

Abstract

Human‐driven environmental changes can induce marked shifts in the functional structure of biological communities with possible repercussion on important ecosystem functions and services. At the same time it remains unclear to which extent these changes may differently affect various types of organisms. We investigated species richness and community functional structure of species assemblages at the landscape scale (1 km2 plots) for two contrasting model taxa, i.e. plants (producers and sessile organisms) and birds (consumers and mobile organisms), along topography, climate, landscape heterogeneity, and land‐use (agriculture and urbanization) gradients in a densely populated region of Switzerland. Our study revealed that agricultural and urban land uses drove marked shifts in the functional structure of biological communities compared to changes along climate and topography gradients, especially for plants, while for birds these changes were comparable. Agricultural and urban land uses enhanced divergence in traits related to resource use for birds (diet and nesting), growth forms, dispersal, and reproductive traits for plants, while it induced convergence in vegetative plant traits (plant height and leaf dry matter content). These results suggest that contrasting assembly patterns may arise within and across taxonomic groups along the same environmental gradients as result of distinct underlying processes and ‘organism‐specific’ environmental perceptions. Our results further suggest a potential homogenization of biological communities, as well as low functional diversity and redundancy levels of bird assemblages in our human‐dominated study region. This might potentially compromise the maintenance of key ecological processes under future environmental changes.

Street trees reduce the negative effects of urbanization on birds

“…This result is confirmed through the low RaoQ index scores, showing that species with similar functional traits are dominant. The urbanization process leads to a reduction in the amount of bird species’ traits, particularly in traits related to resource use and nesting substrate [52,68]. However, our results are in accordance with another study, in which the increase in the amount of arboreal vegetation led to an increase in the community’s functional aspects [69].…”

“…Urban landscapes have large quantities of resources for a portion of the avifauna with similar functional traits [52,68]—which is related to the general low functional richness and RaoQ index scores. Since synanthropic species are negatively influenced by the amount of habitat within urban landscapes [8], urban areas with more available habitat will allow the presence of species with functional traits related to the most preserved areas, leading to changes in the functional diversity indices.…”

“…This process increases community’s functional evenness with a lower number of functional traits. The proximity to parks can reduce the total number of individuals for many bird species, which have functional characteristics related to the more urbanized areas [25,68]. However, species that need a greater amount of habitat, probably, are favored, reducing taxonomic evenness without changing the taxonomic and functional richness, consequently reducing RaoQ.…”

Spatio‐temporal dynamics of multi‐trophic communities reveal ecosystem‐wide functional reorganization

“…6). Previous work on multi-trophic communities found divergent directional trends across taxa when looking at aggregated trait diversity metrics, such as turnover, divergence or evenness (Concepción et al 2017, Magurran et al 2018, Törnroos et al 2019). Previous work on multi-trophic communities found divergent directional trends across taxa when looking at aggregated trait diversity metrics, such as turnover, divergence or evenness (Concepción et al 2017, Magurran et al 2018, Törnroos et al 2019).…”

Analyzing Three-Decadal Patterns of Land Use/Land Cover Change and Regional Ecosystem Services at the Landscape Level: Case Study of Two Coastal Metropolitan Regions, Eastern China

“…Analysis of land use patterns and landscape dynamics affecting ecosystem services could provide a basis for informed decision making towards sustainable ecosystems management [11,19,21,56]. As addressed in Section 3, LULC change and land fragmentation measured with landscape metrics helped quantitatively illustrate the spatiotemporal pattern of deteriorated ecosystem services delivery during recent rural-urban transition.…”