Satellite-based measurements of the normalized difference vegetation index (NDVI; an index of vegetation greenness and photosynthetic capacity) indicate that tundra environments are generally greening and becoming more productive as climates warm in the Arctic. The greening, however, varies and is even negative in some parts of the Arctic. To help interpret the space-based observations, the International Polar Year (IPY) Greening of the Arctic project conducted ground-based surveys along two >1500 km transects that span all five Arctic bioclimate subzones. Here we summarize the climate, soil, vegetation, biomass, and spectral information collected from the North America Arctic transect (NAAT), which has a more continental climate, and the Eurasia Arctic transect (EAT), which has a more oceanic climate. The transects have broadly similar summer temperature regimes and overall vegetation physiognomy, but strong differences in precipitation, especially winter precipitation, soil texture and pH, disturbance regimes, and plant species composition and structure. The results indicate that summer warmth and NDVI increased more strongly along the more continental transect.

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The paper aims to describe Russian approaches to inventory of vascular plants diversity in the Russian Arctic. In the study, the local flora method is used. It provides comparable data for spatial comparisons between different locations. The method includes the study of species distributions within a landscape, therefore the concept of "partial flora" was elaborated. A complex estimate "activeness" allows to assess a species role within the landscape. These theoretical concepts are applied at the local flora of a hardly accessible central part of the Gydansky Peninsula. The local flora numbers 191 vascular plant species. Altogether, 18 habitat types were distinguished with partial floras numbering from 15 to 75 species. The highest alfa-diversity was recorded on steep slopes, many rare species occurred there as well. These habitats occupied less than 10% of the area but provided almost 75% of local flora. Although the morphology of relief was better developed at this locality compare to the others at the Gydansky Peninsula, the intralandscape structure of flora is continuous, showing a low beta-diversity and high similarity of species composition between different habitats. It is explained by a high proportion of "active" species, which occur in many different habitat types. Along the zonal gradient within the Gydansky Peninsula, a decrease of species richness at local flora level was found but no change at partial floras level.

Plant communities are coupled with abiotic factors, as species diversity and community composition both respond to and influence climate and soil characteristics. Interactions between vegetation and abiotic factors depend on plant functional types (PFT) as different growth forms will have differential responses to and effects on site characteristics. However, despite the importance of different PFT for community assembly and ecosystem functioning, research has mainly focused on vascular plants. Here, we established a set of observational plots in two contrasting habitats in northeastern Siberia in order to assess the relationship between species diversity and community composition with soil variables, as well as the relationship between vegetation cover and species diversity for two PFT (nonvascular and vascular). We found that nonvascular species diversity decreased with soil acidity and moisture and, to a lesser extent, with soil temperature and active layer thickness. In contrast, no such correlation was found for vascular species diversity. Differences in community composition were found mainly along soil acidity and moisture gradients. However, the proportion of variation in composition explained by the measured soil variables was much lower for nonvascular than for vascular species when considering the PFT separately. We also found different relationships between vegetation cover and species diversity according the PFT and habitat. In support of niche differentiation theory, species diversity and community composition were related to edaphic factors. The distinct relationships found for nonvascular and vascular species suggest the importance of considering multiple PFT when assessing species diversity and composition and their interaction with edaphic factors. Synthesis: Identifying vegetation responses to edaphic factors is a first step toward a better understanding of vegetation–soil feedbacks under climate change. Our results suggest that incorporating differential responses of PFT is important for predicting vegetation shifts, primary productivity, and in turn, ecosystem functioning in a changing climate.

The local flora method has been used by Russian botanists for studying vast wilderness areas. The method strives to determine the total flora within a certain limited area and provides comparable data for spatial comparisons between different locations and temporal comparisons at the same location. Complete vascular plant diversity was sampled in 240 localities with an area between 100 and 300 km2 each throughout the Russian Arctic. These data were incorporated in a specially developed Integrated Botanical Information System (IBIS). This database provides a unique opportunity to study spatial gradients of different floristic variables. Pairwise similarity of species composition and proportions of various phytogeographical groups in local floras were used in a floristic subdivision of the Russian Arctic. The floristic units derived by this method often resembled subprovinces of B.A. Yurtsev (1994. J. Veg. Sci. 5(6): 765–776), but there were also several areas of nonalignment. Application of local floras for monitoring of temporal changes has several constraints. However, nine local floras were revisited 20–70 years after the initial survey. Increases in the number of Boreal and Hypoarctic species were recorded in the southern local floras. Standardized methods and the use of modern technical tools for accurate documentation could enable use of this approach at observatories across the Arctic.