『Abstract
　Phosphorus (P) is an important nutrient in tundra ecosystems that co-limits or in some cases limits primary production. The availability of P is largely driven by soil characteristics, e.g., pH, organic carbon, and abundance of P-sorbing elements such as aluminium (Al) or iron (Fe). We tested how vegetation and soil properties relate to P availability across different tundra vegetation types. The different soil P fractions in the organic horizon were measured and plant foliar nitrogen (N) to P ratio and a plant bioassay was used as indicators of plant nutrient status. Microbial bioassays were used to study microbial respiration kinetics and in response to carbon, N, and P amendments. The distribution of P fractions differed significantly across vegetation types; labile fractions of P were less abundant in meadow sites compared to health sites. Calcium-phosphates seemed to be an important P-fraction in meadows, but were only found in lower concentrations in the heath. There were only small differences in NaOH-extractable P between the vegetation types and this correlated with the distribution of oxalate-extractable Al. Plant N:P ratios and the plant bioassay indicated decreasing P availability from dry heath to mesic heath to mesic meadow. The microbial bioassay suggests that the heterotrophic microbial community is C-limited with N as a secondary limiting nutrient although there were indications that microbial P availability was lower in the meadow sites. Overall, we suggest that the observed variations in soil P across vegetation types are affecting both plant and microbial function although the differences seem to be relatively small.

Keywords: Phosphorus availability; Subarctic tundra; Hedley fractionation; soil respiration; N:P ratio』

Introduction
Materials and methods
　Location and vegetation types
　Sampling of soil and plant material
　Microbial respiration measurements
　Soils
　Plant bioassay
　Analysis
　Statistics
Results
　Soils
　Leaf nutrient content
　Microbial responses
Discussion
　Vegetation type and soil P fractions
　Relationship between vegetation type and biotic indices of P availability
　Linkages between soil properties and basal respiration
Conclusion
Acknowledgments
Appendix
References