CONTENTS xvii 



CHAPTER IX 

 ECOLOGY 



PAGE 



A. GENERAL INTRODUCTION . . ' . . . . 356 



B. EXTERNAL INFLUENCES . . . . . . 357 



a. Temperature 



b. Humidity 



c. Wind 



d. Human Agency 



C. LICHEN COMMUNITIES . . . . . 362 



i. ARBOREAL 



a. Epiphyllous 



b. Corticolous 



c. Lignicolous 



i. TERRICOLOUS 



a. On calcareous soil 



b. On siliceous soil 



c. On bricks 



d. On humus 



e. On peaty soil 



f. On mosses 



g. On fungi 



3. SAXICOLOUS . . . . . . . . .371 



a. Characters of mineral substrata 



b. Colonization on rocks 



c. Calcicolous 



d. Silicicolous 



4 . OMNICOLOUS LICHENS 376 



5. LOCALIZED COMMUNITIES 378 



a. Maritime lichens 



b. Sand-dune lichens 



c. Mountain lichens 



d. Tundra lichens 



e. Desert lichens 



f. Aquatic lichens 



D. LICHENS AS PIONEERS . .... 392 



a. Soil-formers 



b. Outposts of vegetation 



CHAPTER X 



ECONOMIC AND TECHNICAL 

 A. LICHENS AS FOOD 395 



a. Food for insects 



b. Insect mimicry of lichens 



c. Food for the higher animals 



d. Food for man 



