Contrasting latitudinal patterns in diversity and stability in a high‐latitude species‐rich moth community

Abstract

Aim Biodiversity is currently undergoing rapid restructuring across the globe. However, the nature of biodiversity change is not well understood, as community‐level changes may hide differential responses in individual population trajectories. Here, we quantify spatio‐temporal community and stability dynamics using a long‐term high‐quality moth monitoring dataset. Location Finland, Northern Europe. Time period 1993–2012. Major taxa studied Nocturnal moths (Lepidoptera). Methods We quantified patterns of change in species richness, total abundance, dominance and temporal variability at different organizational levels over a 20 year period and along a latitudinal gradient of 1,100 km. We used mixed‐effects and linear models to quantify temporal trends for the different community and stability metrics and to test for latitudinal (or longitudinal) effects. Results We found contrasting patterns for different community metrics, and strong latitudinal patterns. While total moth abundance has declined, species richness has simultaneously increased over the study period, but with rates accelerating with latitude. In addition, we revealed a latitudinal pattern in temporal variability—the northernmost locations exhibited higher variability over time, as quantified by both metrics of richness and aggregated species population trends. Main conclusions When combined, our findings likely reflect an influx of species expanding their ranges poleward in response to warming. The overall decline in abundance and the latitudinal effect on temporal variability highlight potentially severe consequences of global change for community structure and integrity across high‐latitude regions. Importantly, our results underscore that increases in species richness may be paralleled by a loss of individuals, which in turn might affect higher trophic levels. Our findings suggest that the ongoing global species redistribution is affecting both community structure and stability over time, leading to compounded and partly opposing effects of global change depending on which biodiversity dimension we focus on.

Nonlinear trends in abundance and diversity and complex responses to climate change in Arctic arthropods

“…2). These results mirror findings from another recent long-term study showing opposing abundance and diversity trends (45). Together, our results indicate that recent abundance increases are driven by a small number of dominant taxa.…”

Meta-analysis of multidecadal biodiversity trends in Europe

“…Such patterns were, for example, observed in vascular plants at coarse scales in Europe due to the extinction of rare native species and spread of alien species 38 . Thus, temporal changes in taxonomic composition, i.e., turnover, are likely to be more sensitive than simply taxonomic richness (i.e., alpha-diversity) and abundance in responses to global change 39,40 . Accordingly, we show that temporal changes in taxon turnover are more pertinent across biogeoregions than the other three studied biodiversity metrics.…”

A window to the world of global insect declines: Moth biodiversity trends are complex and heterogeneous

“…Other multidecadal declines in moth faunas have been reported from Europe (e.g., refs. [21][22][23][24].…”

“…Spatially, moth trends vary at continental, regional, and even local scales, which suggests that different stressors are in play. While patterns of moth decline are prevalent across western, central, and northern European countries (17,(21)(22)(23)(24)26), typically, there is considerable within-country heterogeneity. Conrad et al (17) found that total abundance of macrolepidopterans decreased significantly (by 44%) in the southern half of GB over the period 1968-2002, but showed no overall change in the northern half.…”