Index 



567 



Nitrogen, 231-233 

 absorption, 165-168 

 allocation, 169-171 

 amount in ecosystem, 464 

 budget, 470-471 

 caribou urea cycling, 399 

 content in ecosystems, 460-461 

 denitrification, 243-245, 473 

 distribution in biomass, 



464-465 

 immobilization, 246-249 

 input from precipitation, 



239-240 

 loss in runoff, 240-242 

 mineralization in soil, 245-249 

 nitrification of soil, 249-250 

 transport in soil, 250-252 

 see also Nutrients 



Nitrogen fixation, 253, 473 

 algae, 234-235, 238 

 bacteria, 258-259 

 biomass of organisms, 235-236 

 environmental control, 

 236-239 



Nutrient cycling, 411, 472, 475, 

 477-478 

 long-term changes, 479 

 microorganisms, 331-333 



Nutrient-recovery hypothesis, 

 375-380 



Nutrients, 220-221 



absorption, 165-168, 477 

 allocation, 140, 169-171 

 annual input, 492 

 contribution by lemmings, 



377-378 

 forage, 356-357 

 graminoid growth, 150 

 input from atmosphere, 469 

 invertebrate biomass, 442 

 invertebrate production, 441 

 limit on CO2 uptake, 103 

 loss, 473 

 photosynthesis, 109-110, 173, 



184 

 release, 477 



reservoir in vegetation, 464 

 shoot growth, 171-173 

 soil, 253 

 transfer within ecosystem, 



473-478 

 turnover rates, 476 

 uptake, 477 



see also Nitrogen, Phosphor- 

 us, etc. 

 Nutrient-transport hypothesis, 



406-408 



Ordination 



see Vegetation 

 Organic matter, 331 



accumulation, 473 



carbon, 459 



concentration of invertebrates, 

 441 

 Oxygen 



influence on fungi, 287 



microbial metabolism, 307-309 



soil, 227 



Permafrost, 1, 214, 219-220, 



420, 464, 469 

 Perturbations 



see Disturbance 

 Phalaropes 



see Birds 

 Phosphorus, 231, 233-234 



absorption, 165-168 



allocation, 169-171 



amount in ecosystem, 460-461, 

 464 



availability, 90 



budget, 470-471 



distribution in biomass, 

 464-465 



input, 240 



loss in runoff, 242-243 



mineralization in soil, 245-249 



