Douglas fir zone, 187 



Downgrade series. See Series, down- 

 grade 



Downy chess, downy bromegrass. See 

 Bromus tectorum 



Draba (Whitlow-grasses) 



incana, 139; oblongata, 17; subcapitata, 

 34 



Drosophila melanogaster (Fruit fly), 36 



Dryas (Mountain avens) 



integrifolia (entire-leaved M. a.), 187; 

 octojiora (eight-petaled M. a.), 139 



Dutch elm disease. See Ceratostomella 

 ulmi 



Dwarf shrub-heath, 156, 161 



Dynamics, vegetation, 133-167, 184 



Ecesis, 65 



Ecological amplitude, 14-21, 32, 91, 

 95, 137 

 and competition, 27 

 and constancy, 125 

 and ecotypes, 48 

 and grouping of species, 61-65, 70, 



98, 126 

 definition, 14 



optimum range, 20, 31, 90 

 Ecological relations, 177, 181-184 

 Ecological success of species, 54-58, 



105 

 Ecology, 1 

 Ecosystem, 60, 160 

 Ecotone, 40, 53, 69 

 Ecotype, 15,24,37,45,48,56,91, 171 

 Edaphic factor. See Environmental 



factors 

 Eel grass. See ^ostera 

 Efficiency of species, 22-26 

 Ellison, L., 33 

 Elodea (Waterweed), 95 

 Elymus (Wildrye) 



canadensis (Canada W.), 25, 92; jun- 

 ceus (Russian W.), 22 

 Emergent trees, 82 

 Endemic species, 158 

 Empetrum (Crowberries) 



hermaphrodilum, 139, 157, 161; ni- 

 grum, 63, 139 

 Empetrum zone, 187 



Enceliafarinosa (White brittlebrush), 37 

 Endoconidiophora fagacearum (Oak wilt), 



62 

 Endophyte, 93 



Engelmann spruce-alpine fir zone, 187 

 Environment, 2, 160 



adverse, 44, 47 



physical, 8-10 



reactions of plants on the, 135 



resources of, 73 



variability, 43 

 Environmental complex, 10 

 Environmental factors, 137, 160-161 



and competition, 32 



and phenology, 88 



biotic, 44, 51, 154 



classification, 8 



climatic, 8, 15 



integration of, 87 



limiting (critical), 15, 34, 67, 68, 

 100 



nonreactive, 100 



optimum, 21 



phases, 9 



soil, 8, 15, 73 



topographic, 8, 70 

 Epilobium angustifolium (Fireweed), 41 

 Epiphyte, 94 



Ericaceae (Heath family), 53 

 Erica vagans (Cornish heath), 72 

 Eriogonum multiceps (Umbrella plant), 



145 

 Enophorum vaginatum var. spissum 



(Sheathed cottongrass), 57 

 Erodium cicutarium (Alfilaria), 88 

 Erosion, 73, 176 

 Erythromum americanum (Common 



troutlily), 83 

 Eschscholtzia neomexicana (Mexican 



poppy), 88 

 Establishment, 65 

 Eucalyptus {Eucalyptus), 36, 68 

 Eupatorium adenophorum (Thorough- 

 wort), 53 

 Europe, 48, 82, 87, 103, 105, 125, 



179, 180, 187 

 Eurotia lanata (Winter fat), 85, 98, 99, 



114 

 Euxerophyte, 95 



208 • Index 



