376 



THE STUDY OF PLANT COMMUNITIES 



Dominance— Continued 



relation to basal area, 61 



relation to cover, 61 



seasonal, 65 

 Dormancy and photoperiodism, 142- 



143 

 Drainage, artificial, 209 

 Dryas octopetala, 239 

 Dryopteris dilatata, 241 

 Dunes (see Sand dunes) 

 Dust storm, 109 



Earthworms, 200 

 Ecological training, 14 

 Ecology 



applied, 315-361 



approaches to the subject, 16 



breadth of the field, 14 



definition, 11 



human, 13, 359-361 



objectives, 12, 13 



practical considerations, 315-361 



scope, 13 



static and dynamic viewpoints, 17 



subject matter, 11, 13 

 Edaphic factors, 144-174 

 Eichornia, 206-207 

 Elymus condensatus, 297 

 Elyna bellardii, 239 

 Empetrum nigrum, 239 

 Environment 



a complex of factors, 16, 75 



and life, 12 



and physiological processes, 12 



climatic factors, 75-143 



components, 13 



defined, 13 



factors, 13 

 Ephedra spp., 287 

 Epilobium latifolium, 239 

 Epiphytes, 26, 193 



latitudinal distribution, 193 



Spanish moss, 28, 193 



specificity, 193 



throughout plant kingdom, 193 

 Equinoxes, 116 

 Eriophorum spp., 238 

 Erodium cicutarium, 199 

 Erosion, 327 



control, 333, 334-335 

 Euphorbia, ipecaciianhae, 257 



polygonifolia, 52 

 Eurotia lanata, 286 



Evaporating power of the air, 85 

 Evaporation 



and transpiration, 82-83 

 measurement 

 atmometer, 85, 86 

 evaporimeters, 85 

 open tank method, 85 

 precipitation ratio, 96, 97 

 Evernia vulpina, 272 

 Exchangeable bases, 179-182 

 Exclosures, 42, 312 

 types and uses, 43 

 Exclusives (fidelity), 72 

 Exposure and insolation, 133 



Faciation, 225 



Factors, of the environment, 13 



air, 76-113 



and plant distribution, 15 



biological, 187-210 



climatic, 75-143 



exchangeable bases, 179-182 



insolation, 116-143 



organisms, 187-210 



physiographic, 144-187 



soil, 144-161 



soil acidity, 178-179 



soil atmosphere, 174-177 



soil water, 161-174 



temperature, 118-127 



topography, 185-187 



wind, 97-115 

 Fagus grandifolia, 246, 248, 249-250, 



253 

 Fairy rings, 182 

 Fallugia paradoxa, 269 

 Festuca idahoensis, 297 

 Fidelity, 72-73 



and constance, 73 



characteristic species, 72-73 



classes, 72 

 Field capacity, soil, 168 

 Field margin, plantings, 331 

 Fimbristylis casta?iea, 52 

 Fire 



and pine savannah, 254, 256 



as a factor, 215, 266-267 



controlled burning, 205 



effects, 203-204-205, 226-227, 282- 

 283 

 Fish ponds, 329 

 Fixation of nitrogen, 196-197 

 Flourensia, 297 



