Post- Pleistocene Era (Continued) 

 growth during sub- Atlantic period 



of, 291 

 historic fluctuations of climate in, 



291 

 melting of ice and remaining of 



local glaciers in, 288 

 rapidity of melting of ice in, 288 

 retreat of grassland during, 326 

 Precipitation: 

 amount of in arctic regions of 



North America, 315 

 and ultra-violet rays, effect of on 



organisms, 99 

 and vegetation, as factors in dis- 

 persal of species, 148-149 

 as factor in change of grassland to 



present desert, 286 

 as favoring decomposition of 



organic ground matter, 165 

 as form of moisture available to 



organisms, 97 

 as heavy during glacial stages, 



284-285 

 as heavy during historic climate 



fluctuations, 291 

 as heavy during Pleistocene era 



and extension of grassland, 326 

 as masking effect of ultraviolet 



rays, 244 

 correlation of with sunspot cycle, 



243 

 decrease of as factor in shrinkage 



of ponds, 87 

 degree of in North America 60-70 



million years ago, 281 

 effects of on animals in flood- 

 plain, 114 

 effect of on distribution of plankton 



in lakes, 69 

 frequent, as carrier of soil nutri- 

 ents, 168-169 

 inadequacy of and hardpan forma- 

 tion, 170-171 

 in alpine tundra, 316 

 in deserts and consequent plant 



and animal activity, 338-339 

 in forests, stem- flow, 121 

 in North American deserts, 332 

 in North American grassland, 324 

 "interception" of, 121 

 in tropical biomes, 340-341, 341 

 in woodland biome: 

 lack of as increasing mortality of 



muskrats, 87 

 mean annual rate for temperate 



deciduous forest biome in 



North America, 293 

 measurement of through fall in 



forests, 121 

 "net rainfall" in forests, defined. 



121 



Precipitation (Continued) 



rate of in coniferous forests, 301- 

 302 



runoff of into lakes and streams, 

 65 

 Predation: 



and "balance of nature" concept, 

 195-196 



and population balance of trophic 

 levels, 202 



and value of concealing coloration 

 of prey, 194 



as a density- dependent factor in 

 populations, 220-221 



as force in maintaining maximum 

 productivity yield, 208 



as lacking in pressure in coral 

 reef biome and color of fishes, 

 367 



buffer species in, 225-226 



by coyotes on pronghorn antelope, 

 328-329 



classification of energy transferred 

 in, 202 



compared to competition, 182 



concentration of carnivores on one 

 species in, 192 



crop pest control through introduc- 

 tion of, 227 



cycle of predator dependent on 

 cycle of prey in, 239 



difficulties in quantitative deter- 

 mination of significance of, 225 



experimental studies in, 225, 225- 

 226 



importance of in maintaining health 

 and vigor in prey populations, 

 226 



in communities with a large num- 

 ber of species, 226 



in communities with a small num- 

 ber of species, 226 



increase in percentage of, with 

 density of prey population in 

 intercompensation with competi- 

 tion, 231 



interdependence between popula- 

 tions of prey and predator 

 species in, 196 



interrelations of any two species 

 in as affected by other species, 

 225-226 



lack of random behavior in search 

 for prey in, 227 



on lemmings and cyclic changes, 

 240 



on prey species by varying num- 

 bers and kinds of predators, 

 226 



on small grassland mammals, 

 329 



parasitoidism as form of, 182 



Predation (Continued) 



periodic oscillations in numbers 

 of both species, given single 

 prey and predator and limited 

 area, 239-240 



protection from by hanging from 

 trees, 346 



role of in keeping populations of 

 competing species below level 

 food resources of habitat can 

 sustain, 252-253 



transfer of energy to higher trophic 

 levels through, 201 



upper limit of vulnerability in, 231 



use of to control plagues, 234-235 



variations in rate of with carrying 

 capacity of area for prey, 225 



vulnerability of prey species in as 

 proportional to its relative 

 abundance, 192 

 Predominants (see also Dominance; 

 Dominants): 



and fifty per cent rule. 29 



as key to recognition of communi- 

 ties, 27 



in ocean as defining biomes, 276 



in oceanic plankton and nekton | 



biome, 359 * 



in pelecypod-annelid biome of sea, J 

 365 ' 



in taxonomic structure of com- 

 munities, 255 

 Preferendum: 



defined. 13 



in choosing of niche by species, 

 250 



of forest animals for stratum like 

 native microhabitat: 



of insects in experimental gradi- 

 ents, 123-124 

 Productivity (see also Productivity 

 Values; Productivity Yield): 



and biomass in lakes, 75-76 



and biomass in ponds, 90-91 



and biomass in streams, 55-56 



basic problem in measurement of, 

 202-203 



biological, progressive decrease 

 in from shallow waters to open 

 ocean, 356 



calculation of and rate of repro- 

 duction, 217 



carrying capacity in, defined. 21 



factors in variations in for marine 

 plankton, 361-362 



in climax communities, 206-207 



in coral reef biome, 367 



in serai communities, 206-207 



of bottom-dwelling marine organ- 

 isms, 366 



of lakes and rivers of Arctic 

 tundra, 319 



436 



Index 



