The International Tundra Experiment (ITEX): 30 years of research on tundra ecosystems

Abstract

The International Tundra Experiment (ITEX) was founded in 1990 as a network of scientists studying responses of tundra ecosystems to ambient and experimental climate change at Arctic and alpine sites across the globe. Common measurement and experimental design protocols have facilitated synthesis of results across sites to gain biome-wide insights of climate change impacts on tundra. This special issue presents results from more than 30 years of ITEX research. The importance of snow regimes, bryophytes, and herbivory are highlighted, with new protocols and studies proposed. The increasing frequency and magnitude of extreme climate events is shown to have strong effects on plant reproduction. The most consistent plant trait response across sites is an increase in vegetation height, especially for shrubs. This will affect surface energy balance, carbon and nutrient dynamics and trophic level interactions. Common garden studies show adaptation responses in tundra species to climate change but they are species and regionally specific. Recommendations are made including establishing sites near northern communities to increase reciprocal engagement with local knowledge holders and establishing multi-factor experiments. The success of ITEX is based on collegial cooperation among researchers and the network remains focused on documenting and understanding impacts of environmental change on tundra ecosystems.

Increased biocrust cover and activity in the highlands of Iceland after five growing seasons of experimental warming

“…Experimental warming was simulated with OTCs (Hollister et al, 2023) that were built according to the protocols of the International Tundra Experiment (ITEX; Henry and Molau, 1997;Henry et al, 2022). We used a randomized block design.…”

Bryophytes dominate plant regulation of soil microclimate in alpine grasslands

“…Graminoid abundance in particular has been found to increase with warming (Brooker and van der Wal 2003, Elmendorf et al 2012, Winkler et al 2016), resulting in reduced forb abundance (Jaroszynska 2019) and declines in bryophyte cover (Van Der Wal and Brooker 2004, Klanderud and Totland 2005, Elmendorf et al 2012, Lang et al 2012). Alpine plant communities are becoming taller with warming (Bjorkman et al 2018, Henry et al 2022). Since alpine regions are greening faster than ever (Rumpf 2022), it is increasingly important to understand how low‐stature alpine vegetation regulates microclimate in alpine regions.…”

More Snow Accelerates Legacy Carbon Emissions From Arctic Permafrost

“…Here, we report the impacts of deeper snow on the carbon and nitrogen balance of permafrost ecosystems and soils, capitalizing on a 25‐yearlong International Tundra Experiment (ITEX) (Henry et al., 2022; M. D. Walker et al., 1999) snow addition experiment in a common tundra system in Northern Alaska (Jones et al., 1998). The unique duration of this experiment overcomes the challenge posed by large inter‐annual weather variability when assessing climate manipulation effects in the Arctic (Lupascu et al., 2013, 2014) and has allowed a realistic cascade of interacting physical and ecological changes to accumulate that offer a unique window into one future Arctic scenario.…”

“…Here, we report the impacts of deeper snow on the carbon and nitrogen balance of permafrost ecosystems and soils, capitalizing on a 25-yearlong International Tundra Experiment (ITEX) (Henry et al, 2022;M. D. Walker et al, 1999) snow addition experiment in a common tundra system in Northern Alaska (Jones et al, 1998).…”