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Northern peatlands are very sensitive to changes in climate. Impacts of increased temperatures on hydrology, vegetation structure and soil carbon are already well documented from northern peatlands. In contrast, effects of global warming on soil mites, and seasonal effects in particular, have received less attention, even though soil mites are an important component in ecosystems as they contribute to nutrient dynamics and decomposition. We investigated the impacts of long-term (16 years) experimental seasonal climate manipulations (summer warming, winter warming with snow accumulation, and year-round warming) on oribatid (Oribatida) and mesostigmatid (Mesostigmata) mite communities in a peat bog underlain by discontinuous permafrost, in Abisko, Northern Sweden. We found that (1) Year-round warming treatment had neither impact on life-history trait compositions nor on total abundances of oribatid mites, possibly because of opposite effects of summer and winter warming; (2) Small-bodied oribatid mites, in particular those belonging to genera Suctobelba, increased in abundance under the summer warming treatment; (3) The species richness of oribatid mites was negative affected by year-round warming; (4) Mesostigmatid mites, which were not identified to species level, were found to decrease in abundance under year-round warming. Because different mite taxa with different body sizes and diets play distinct roles in carbon and nutrient dynamics, the observed changes in mite communities may impact ecosystem functions in northern peatlands. [ABSTRACT FROM AUTHOR]

1. A fundamental trade-off among vascular plants between traits inferring rapid resource acquisition and those leading to conservation of resources has now been accepted broadly, but is based on empirical data with a strong bias towards leaf traits. Here, we test whether interspecific variation in traits of different plant organs obeys this same trade-off and whether within-plant trade-offs are consistent between organs. 2. Thereto, we measured suites of the same chemical and structural traits from the main vegetative organs for a species set representing aquatic, riparian and terrestrial environments including the main vascular higher taxa and growth forms of a subarctic flora. The traits were chosen to have consistent relevance for plant defence and growth across organs and environments: carbon, nitrogen, phosphorus, lignin, dry matter content, pH. 3. Our analysis shows several new trait correlations across leaves, stems and roots and a striking pattern of whole-plant integrative resource economy, leading to tight correspondence between the local leaf economics spectrum and the root ( r = 0.64), stem ( r = 0.78) and whole-plant ( r = 0.93) economics spectra. 4. Synthesis. Our findings strongly suggest that plant resource economics is consistent across species’ organs in a subarctic flora. We provide thus the first evidence for a ‘plant economics spectrum’ closely related to the local subarctic ‘leaf economics spectrum’. Extending that concept to other biomes is, however, necessary before any generalization might be made. In a world facing rapid vegetation change, these results nevertheless bear considerable prospects of predicting below-ground plant functions from the above-ground components alone. [ABSTRACT FROM AUTHOR]

Abstract: In high-latitude ecosystems climate change induced plant community shifts toward dominance of shrubs and trees will potentially have large consequences for soil carbon dynamics. Changes in the litter layer due to an altered quantity and quality of litter input, or by its indirect effect on the microclimate, might affect the decomposer community. To be able to predict the effects of increased litter input on decomposers and consequently on soil carbon dynamics, we studied the contribution of Collembola to carbon processing in a high-latitude peat bog system. Moreover, we assessed the effects of changing litter inputs on their abundance, diversity and diet choice, using a 13C tracer approach. The δ 13C signatures of Collembola in peat moss (Sphagnum fuscum) showed that species differed in their diet. However, when vascular plant litter (Betula pubescens) entered the Sphagnum peat ecosystem, the δ 13C signatures of the Collembola, changed and species-specific differences disappeared. There were no significant changes in Collembola species composition and density after Betula litter addition, but all species showed a strong dietary preference for Betula-associated food sources over Sphagnum; 67% of their diet contained carbon originating from Betula litter. Decomposition patterns corresponded to these findings; mass loss (after 406 days of incubation) of Betula increased from 16.1% to 26.2% when decomposing in combination with Sphagnum, and Sphagnum decomposed even slower in combination with Betula litter (from 4.7% to 1.9%). Our results indicate that the change in litter quality rather than its effects on microclimate is the main way in which vascular litter inputs alter the role of Collembola in carbon turnover. Collembola are plastic in their diet choice, which implies that changes in carbon turnover rates in situations where vegetation shifts occur, might well be due to diet shifts of the present decomposer community rather than by changes in species composition. [Copyright &y& Elsevier]

Abstract: Ecosystems at high northern latitudes are subject to strong climate change. Soil processes, such as carbon and nutrient cycles, which determine the functioning of these ecosystems, are controlled by soil fauna. Thus assessing the responses of soil fauna communities to environmental change will improve the predictability of the climate change impacts on ecosystem functioning. For this purpose, trait assessment is a promising method compared to the traditional taxonomic approach, but it has not been applied earlier. In this study the response of a sub-arctic soil Collembola community to long-term (16 years) climate manipulation by open top chambers was assessed. The drought-susceptible Collembola community responded strongly to the climate manipulation, which substantially reduced soil moisture and slightly increased soil temperature. The total density of Collembola decreased by 51% and the average number of species was reduced from 14 to 12. Although community assessment showed species-specific responses, taxonomically based community indices, species diversity and evenness, were not affected. However, morphological and ecological trait assessments were more sensitive in revealing community responses. Drought-tolerant, larger-sized, epiedaphic species survived better under the climate manipulation than their counterparts, the meso-hydrophilic, smaller-sized and euedaphic species. Moreover it also explained the significant responses shown by four taxa. This study shows that trait analysis can both reveal responses in a soil fauna community to climate change and improve the understanding of the mechanisms behind them. [ABSTRACT FROM AUTHOR]