Index 



531 



Prairie coiiiiminity, 419 

 Prairie dogs, 310 

 Prairie soils, 85 

 Prairies, 124 



see also Life zones 

 Precipitation-evaporation ratio, 125- 



126, 183-184 

 Predation, 392-396 

 Predator-prey fluctuations, 397-399 

 Pressure, 27-32 



in air, 28-29 



in water, 29-30 

 Primary succession, 432 

 Principle, Bergmann, 157 



of common transport, 248 



of edges, 412-413 



of minimum population, 327 



of partial equivalence, 75 

 Producers, 467-468 



in the sea, 474-476 

 Production pyramid, 469 

 Production rate, 482-483, 493-500 

 Productivity, concepts of, 482-500 



of land and water, 500-503 



relation to material removed, 489- 

 493 

 Protective coloration, 60, 199-202 

 Pteropod ooze, 71 

 Pyramid of biomasses, 470 

 Pyramid of numbers, 471-472, 482 

 Pyramiding in tree growth, 234 



Qio, 152 

 Quail, 413-414 



Radiation, solar, 186-191 

 Radiolarian ooze, 71 

 Ragweed, photoperiodism in, 226 

 Rainfall, 109-111 



in relation to temperature, 113-115 

 Rain-forest, 234-235 

 Ranatra, 210 

 Range animals, 472, 502 

 Recognition in group organization, 313- 



316 

 Recruitment, 346 

 Red tide, 384 

 Redfish, 295 



Redox potential, 251-253 

 Reef building, 69, 274-275 



see also Corals 



Regeneration, of nutrients, 304-308 



rate, of 305 



ratio of materials, 306-307 

 Remora, 378 



Reproduction, in colonial birds, 324- 

 325 



effect of photoperiod on, 227-229 



effect of population density on, 320- 

 321, 323-328 



production of aggregations by, 309- 

 310 

 Respiratory systems, adaptations of, for 



water conservation, 120 

 Return migration, 355-357 

 Rheotaxis, 57 

 River communities, 417 

 Root secretions, 78 

 Roots, 76 



in relation to oxygen, 253-254 



in relation to water, 121-122 



Sacculirui, 390 



Sagitta as indicator species, 50 



Saline soil, 97 



Salinity, limiting effects of, 97-99 

 of natural waters, 92-95 



Salmon, spawning of, 313—314 



Salt, content of natural waters, 94 

 lakes, 93-94 



Salt-marsh community, 403 



Sand, organisms in, 24, 417 



Sand dunes, succession in, 440-441 



Saprophytes, 278, 467-468 



Sargassiirn, 50 



Saturation deficit, 115-116 



Sawgrass, 406, 445 



Scattering layer in oceans, 218 



Scavengers, 467-468 



Sea anemone, symbiotic relationships, 

 369-370 



Sea lions, 329-330 



Seals, fur, 310, 329 



Secondary succession, 435-438 



Seeds, distribution by animals, 373 

 distribution by water, 48, 442 

 distribution by wind, 46 

 resistance to desiccation, 121 

 resistance to temperature extremes, 

 144-145 



Sequoia, 4, 7, 33 



Serai index, 438 



