Climate change effects on Arctic species spread across trophic levels

Climate change effects on Arctic species spread across trophic levels

Top image: A Dunlin (Calidris alpine) chick. Long-term data on the timing of reproduction of waders was one of the factors analysed in the study. Photo: Lars Mortensen.

Extreme events like the mild winter experienced in Longyearbyen last year, with rain, sleet and positive temperatures, may become more frequent in the future Arctic climate, and thereby challenge the inherent resilience of Arctic species and the ecosystems in which they are part of.

5 October 2016
Text: UNIS

Although the knowledge of how different species in the Arctic respond to long-term changes have grown considerably in recent years, our emerging knowledge of how and to what extend direct effects on species propagate through interactions across trophic levels is still challenged.

Snow cover and snow melt critically important
UNIS professor Mads Forchhammer together with scientists from the Technical University of Denmark, Aarhus University and University of Copenhagen has published a paper in the journal Polar Biology investigating the cumulative long-term influence of the timing of spring snowmelt on the tri-trophic system of waders, arthropods (invertebrates with segmented bodies) and plants at Zackenberg in Northeast Greenland, approximately 400 km south of Longyearbyen.

Zackenberg Research Station in Northeast Greenland.

Zackenberg Research Station in Northeast Greenland. Photo: Mads Forchhammer.

For the arctic terrestrial environment, snow cover and, in particular spring snowmelt, is of critical importance in controlling ecosystem function.

The scientists approached 17 years of data from the monitoring programme Zackenberg Ecological Research Operations (ZERO), using structural equation models, a type of biological network analysis particularly well suited for investigating multiple interactions across different levels.

The results demonstrated that the effects of annual changes in the timing of snowmelt were manifested in the tri-trophic system of waders-arthropods-plants, in two principle ways.

First, the time of snowmelt directly affected plant and arthropod phenology (time of flowering and emergence, respectively) as well as the performance (reproduction) of waders, arthropods and plants.  That is, all species on all trophic levels were directly affected, which suggest a strong potential for the increase of climate effects across trophic levels.

Second, the study also showed that timing of snowmelt indirectly influenced wader phenology as well as the performance of waders, arthropods and plants through effects on adjacent trophic levels. The study provides an added knowledge base for investigating how climate changes may change the Arctic nature.

Mountain avens (Dryas octopetala)

Mountain avens (Dryas octopetala). The timing of flowering was investigated in the study. Photo: Lars Mortensen.

Svalbard approach next
The researchers will adopt the model to Svalbard, more specifically to Adventdalen outside Longyearbyen, which is UNIS’ terrestrial research area.

The Arctic Biology department at UNIS is already looking into what last winter, with high temperatures and rain, has done to the terrestrial ecosystem in Svalbard. In prolongation the model used on the Zackenberg data, will be adapted to Svalbard, to get a clearer understanding of how climate change will affect the local terrestrial ecosystems, Forchhammer says.

Reference
Mortensen LA, Schmidt NM, Høye TT, Damgaard C & Forchhammer MC (2016) Analysis of trophic interactions reveals highly plastic response to climate change in a tri-trophic High-Arctic ecosystem. Polar Biology, DOI 10.1007/s00300-015-1872-z.

For further information contact Mads Forchhammer; mads.forchhammer@unis.no.

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