Effect of simulated environmental change on alpine soil arthropods

Abstract

The effects of environmental change on soil animal communities are poorly known. Norwegian mountains are subject to both atmospheric nitrogen deposition and increased temperature. In a nutrient poor alpine Dryas heath in south Norway, soil arthropods were studied after 4 years of simulated environmental change by warming and/or nutrient addition. Warming alone only affected three low-density Collembola species, while nutrient addition, with or without warming, greatly changed the dominance hierarchy of the microarthropod community. Certain Collembola species with a short (1 year) life cycle and predatory Gamasina mites increased markedly in density. These groups may have been favored by increased litter production, as plant biomass and litter producing graminoids and forbs increased significantly in plots with nutrient addition and nutrient addition combined with warming. Microarthropods with a longer life cycle, such as Oribatida and certain Collembola, were generally unaffected by nutrient addition and probably need more time to respond. The number of Oribatida taxa was, however, reduced in plots with nutrient addition, both with and without warming. A groundliving species of Coccoidea (Homoptera) declined in plots with nutrient addition and warming compared with only warming, probably due to reduced cover of its host plant Dryas. The density of Diptera larvae (Sciaridae and Chironomidae) was unaffected by the treatments. Our results show that increased nutrient availability in nutrient poor alpine soils may have large but different effects on different taxa of soil animals. Species with short life cycles reacted first. Nutrient addition and nutrient addition combined with warming resulted in several effects below ground on microarthropods as previously shown above ground on plants: Increased biomass, high dominance of a few rapidgrowing species, contrasting responses of closely related species, and a reduction in species numbers. These short-term responses may have profound long-term effects in this alpine ecosystem.

Impacts of twenty years of experimental warming on soil carbon, nitrogen, moisture and soil mites across alpine/subarctic tundra communities

“…A similar, but short-term, study to this found no effects of four years of experimental warming on oribatid mites15. However, the life cycle of oribatid mites often spans several years39, and this, in combination with high weather variability between years, may have masked the effects of the limited experimental warming applied in that study1525.…”

“…However, the life cycle of oribatid mites often spans several years39, and this, in combination with high weather variability between years, may have masked the effects of the limited experimental warming applied in that study1525. This interaction between between-year variability and experimental warming effect has previously been demonstrated in a short-term study which found that the warming effect on soil fauna depended on whether the summer was relatively warm and dry, or cool and wet57.…”

Side by side? Vascular plant, invertebrate, and microorganism distribution patterns along an alpine to nival elevation gradient

“…Other organism groups may remain resistant or may be similarly affected, which would be of particular concern owing to the above-average level of endemic invertebrates compared to elevations below the timberline in the Alps (Rabitsch et al 2016). For alpine soil arthropod abundance, experimental warming was most effective when combined with nutrient addition (Hågvar and Klanderud 2009), whereas a long-term warming experiment had no effect on richness and abundance of springtails in alpine subarctic ecosystems (Alatalo, Jägerbrand, and Čuchta 2015). Changes in occurrence and activities of microorganisms would be especially relevant to climate change considering their attributes as key players for methane formation and consumption, belonging to methanogenic archaea and methanotrophic bacteria, respectively (Crutzen and Lelieveld 2001;Hofmann et al 2016b;Praeg, Wagner, and Illmer 2017).…”

Effects of management regimes and extreme climatic events on plant population viability in Eryngium alpinum

“…A global increase of temperature will lead to an increase of ecosystem productivity in the Alps (Theurillat and Guisan, 2001), accelerating forest regeneration following land abandonment and thus loss of habitat for alpine and subalpine herbaceous species as E. alpinum (Dirnbock et al, 2003;Engler et al, 2011). Climate warming will also lead to modifications in species interaction, community dynamics and productivity, and ecosystem processes (Araujo and Luoto, 2007;Easterling et al, 2000;Hagvar and Klanderud, 2009;Klanderud, 2010). Some drought-tolerant grasses as Festuca paniculata (growing at high density in the DES site) may benefit from an increasingly drier and hotter climate and outcompete E. alpinum (Sandra Lavorel, Laboratoire d'Ecologie Alpine, unpublished manuscript).…”