Comparative vegetation survey with focus on cryptogamic covers in the high Arctic along two differing catenas

Abstract

Although cryptogamic covers are important ecosystem engineers in high Arctic tundra, they were often neglected in vegetation surveys. Hence we conducted a systematic survey of cryptogamic cover and vascular plant coverage and composition at two representative, but differing Arctic sites (Ny-Ålesund, Svalbard) along catenas with a natural soil moisture 2 gradient, and integrated these data with physical-chemical soil properties. Soil samples were taken for comprehensive pedological and mineralogical analyses. Vegetation surveys were conducted based on classification by functional groups. Vascular plants were identified to species level. Correlation and multivariate statistical analysis were applied to determine the key environmental factors explaining vegetation patterns along the soil moisture gradients. We observed significant differences in gravimetric water, soil organic matter and nutrient contents along the moisture gradients. These differences were coincident with a shift in vegetation cover and species composition. While chloro-and cyanolichens were abundant at the drier sites, mosses dominated the wetter and vascular plants the intermediate plots. Twenty four vascular plant species could be identified, of which only six were present at both sites. Cryptogamic covers generally dominated with maximum areal coverage up to 70% and hence should be considered as a new additional syntaxon in future ground-truth and remote sensing based vegetation surveys of Svalbard. Multivariate analysis revealed that soil moisture showed the strongest relation between vegetation patterns, together with NH 4-N and pH. In conclusion, soil moisture is a key driver in controlling cryptogamic cover and vegetation coverage and vascular plant species composition in high Arctic tundra.

Consistent trait–environment relationships within and across tundra plant communities

“…In tundra, plants distribute a large part of their biomass below ground surface, as their roots are relatively shallow 110,111 . The rooting depth of plants is limited due to permafrost and a rather shallow A-horizon 112 , consequently, plant-available water is found in the top-soil layer 53,55 . We used a hand-held time-domain reflectometry sensor to measure soil moisture (as volumetric water content (VWC%)) up to a depth of 10 cm in the low-Arctic site and 7.5 cm in the rest of the sites (FieldScout TDR 300; Spectrum Technologies, Plainfield, IL, USA).…”

Five decades of terrestrial and freshwater research at Ny-Ålesund, Svalbard

“…Radiocarbon dating indicates soil C ages of 2000-31 000 calibrated years before present at 11-31 cm depths (Wojcik et al 2019). Quartz is the dominant mineral in soils (34-74% of dry mass), followed by dolomite (5-32%) and calcite, muscovite, biotite, chlorite, Na-plagioclase and K-feldspar (all <13%) (Kern et al 2019). Other than in historical coal mining areas, soils are typically weakly acidic to alkaline, with pH values in the vicinity of Ny-Ålesund ranging between 6.0 and 8.5 .…”

“…Cryptogams dominate the vegetation on Brøggerhalvøya (Arnell & Mårtensson 1959;Williams et al 2017;Kern et al 2019). Cryptogamic cover, which is strongly influenced by water availability Uchida et al 2002;Uchida et al 2006;Kern et al 2019) and also by soil fertility and bacterial diversity (Duran et al 2021), encompasses a range of community types, such as biological soil crusts, composed of various micro-organisms (algae, protists, bacteria and fungi; Yoshitake et al 2010), with lichens and bryophytes dominating later successional stages (Fig. 2h).…”

“…Mosses are the most abundant bryophytes, with approximately 130 species occurring on the peninsula, and about 55 species of leafy liverworts are also present (Arnell & Mårtensson 1959;Elvebakk & Prestrud 1996; Table 1), many of which are pan-Arctic taxa, occurring in the Canadian High Arctic and Greenland (Damsholt 2013;Hassel et al 2014). In comparison with cryptogams, vascular plant cover is typically low to moderate (Kern et al 2019), except in habitats with mild microclimates, such as the west-facing bird cliff at Ossian Sarsfjellet (Fig. 2g), which is one of the warmest locations around Kongsfjorden (Daniel et al 2010).…”

Microbial Communities in Biocrusts Are Recruited From the Neighboring Sand at Coastal Dunes Along the Baltic Sea

“…), or barren soil. Biocrusts generally occupy soil spaces free of vascular plants, and thus can represent up to 70% of the living cover (Kern et al, 2019 ). They can be characterized as “ecosystem-engineers” forming water-stable aggregates that have important, multifunctional ecological roles in primary production, nitrogen (N) cycling, mineralization, water retention, and stabilization of soils and dust trapping (Evans and Johansen, 1999 ; Reynolds et al, 2001 ; Lewis, 2007 ; Castillo-Monroy et al, 2010 ).…”