Warming over the last 15 years has altered the functional composition of high-arctic arthropod communities

Background/Question/Methods

In recent decades, the Arctic has experienced the greatest amount of climate change on the planet, and this could have important implications for the structure and function of high latitude communities. While a number of short-term experimental studies demonstrate the sensitivity of terrestrial arthropods to changing environmental conditions, it is unclear whether or not long-term community responses to arctic warming mirror the experimental predictions. Our work addresses the general question of whether the composition of arthropod communities from high-arctic Greenland has shifted in conjunction with warming. Weekly summertime arthropod data were collected from three different ecotypes (wet fen, mesic heath, and arid heath) by the Zackenberg Basic monitoring program between 1996-2011. We considered the annual communities for each of the monitored plots to be the total number of animals caught over the course of the season. We then used nonmetric multidimensional scaling (NMS) to ordinate the arthropod communities and determine how changes in community composition were related to temperature trends and other environmental variables.

Results/Conclusions

Over the 15-year study period, there was a community-wide shift in the relative abundances of detritivores, herbivores, and predators. The community steadily lost Collembola over time, while Hemiptera abundances increased. Numbers of Acarina, Diptera, Lepidoptera, Hymenoptera, and Araneae experienced short-term fluctuations over the measured time period without any indication of longer term changes in their populations. The overall shift in the arthropod community was highly related to the warming trends in high-arctic Greenland. This study is the first to demonstrate that non-experimental long-term warming in the Arctic is differentially affecting different functional groups and thus changing the composition of the entire arthropod community.