PLOS Science Wednesday: Hi reddit, we’re Caspar and Eelke, and our
research shows a more than 75% decline in the biomass of flying insects
over 27 years, indicating severe disturbances in many ecosystems – Ask
us Anything!
Abstract
Hi Reddit, My name is Caspar Hallmann and I am PhD candidate at the
Radboud University in Nijmegen, the Netherlands. My research focuses on
population dynamics of birds and plants in relation to landscape and
climate changes. My name is Eelke Jongejans and I am Assistant Professor
at the Radboud University in Nijmegen, the Netherlands. My research
focuses on spatial population dynamics: I’m interested in the
demographic and driving processes that can explain why certain
populations increase in number, while others dwindle. We recently
published a study titled More than 75 percent decline over 27 years in
total flying insect biomass in protected areas in PLOS ONE. The aims
were to see whether the total weight of insects flying in German nature
areas has changed over time, and whether a change can be understood by
considering climate change, land use change and local changes in plant
species composition. The insect biomass data were painstakingly
collected by our German co-authors of the Entomological Society Krefeld,
using highly standardized traps from 1989 till 2016. Approximately every
11 days they placed a new bottle with ethanol, resulting in 1503 samples
collected in 63 different sites. About half of the sites were visited in
more than 1 year, resulting in 96 site-year combinations. To analyze
this complex dataset we modeled daily biomass as a function of
explanatory variable like habitat cluster, weather variables, plant
species richness, proportion of land covered by agricultural fields in a
200m radius. While these variables explained a considerable amount of
variation between the collected samples, they could not explain the
overall 76% decline in insect biomass that we found over the 27 years.
We will be answering your questions at 1pm ET – Ask Us Anything! Unsure
what to ask? Read an interview with Caspar Hallmann on PLOS Research
News.