Prairie, 85, 89 



and high fidelity species, 127 



mixed, 68, 140 



tallgrass, 68, 78, 80, 140, 185 

 Presence, 121, 124-126 

 Prevernal aspect, 87 

 Prickly pear. See Opuntia 

 Principles, ecological, 8 

 Procedidochares utilis (Tetrid gall fly), 53 

 Producers, 60 

 Productivity, 149, 159, 163 

 Progression of communities, 148-156 

 Province, biotic, 147, 186 

 Primus avium (Sweet cherry), 181 

 Pseudotsuga taxifolia (Douglas fir), 36, 



183, 184 

 Pteridium aquilinum latiuscula (Bracken 



fern), 37, 84 

 Puccinellia (Alkaligrasses) 



airoides, 71; nuttalliana, 145 

 Pueraria thunbergiana (Kudzu), 21 

 Purshia tndentata (Antelope-brush), 31, 

 41 



Quadrat, 104, 114, 162 

 See also Sample area 



Quercus (Oaks), 38, 43, 181, 187 



alba (white O.), 83; borealis (red O.), 

 43; prinus (swamp chestnut O.), 

 101, 142; pubescens, 187; robur 

 (English O.), 87; rubra (red O.), 

 101, 142; sessiliflora (durmast O.), 

 87; velutina (black O.), 43; virgim- 

 ana (live O.), 20 



Random distribution, 113 

 Range readiness, 108 

 Ranuculus nivalis (Snow buttercup), 58 

 Raunkiaer, C, 113 

 Reaction, 21, 26,65, 72 

 Reconnaissance of vegetation, 131, 

 172, 177, 185 



ocular, 103 



range, 103 

 Reedgrass community, 67 

 Regular spacing, 113 

 Reindeer, 116, 162 



Reindeer moss. See Cladonia 

 Relationship of communities, 126 

 Relict, 61, 127, 155 

 Replacement change, 65, 132, 142- 

 145, 146, 150, 159 



cyclic, 136, 142-145 



noncyclic, 136, 142 



phasic, 159, 166 

 Reproduction, 42 



vegetative, and sociability, 79 

 Requirements of species, 10-14, 28- 

 29, 34 



and competition, 28-33 



and grouping of species, 60-61 

 Reseeding rangeland, 58 

 Retrogression, 136, 145, 148, 153, 166 

 Rhus trilobata (Lemonade sumac), 185 

 Rocky mountains, 30, 187 

 Root, nodule, 53 



system and competition, 30-32 

 Riibel, E., 177 

 Rubus occidentalis (Common blackcap), 



41 

 Rudbeckia occidentalis (Coneflower), 46 

 Russia, 17, 93 

 Russian thistle. See Salsola 

 Ryegrass (Lolium), 51 



Sagebrush. See Artemisia 

 Saguaro. See Carnegiea 

 Sahara, 40 

 Salicornia (Glassworts), 56 



herbacea, 124 

 Salix (Willows) 



glauca, 162; herbacea (pygmy W.), 58, 



157; interior (sandbar W.), 41; 



nigra (black W.), 41; polaris, 16, 



34, 58; pulchra, 41 

 Salsola kali (Russian thistle), 11, 22, 



41,47,51,96, 97, 145 

 Sample area, 103, 105, 114 

 Sampling unit, size, number, 124 

 Saperda (a beetle), 52 

 Savanna, 82, 89, 128, 155 

 Saxifraga (Saxifrages), 58 



oppositifolia (twinleaf S.), 16, 34, 139 

 Scandinavia, 56, 82, 105, 129, 139, 



158 



214 • Index 



