Chapter IX: Ecology

A. GENERAL INTRODUCTION 356

B. EXTERNAL INFLUENCES 357
_a._ Temperature
_b._ Humidity
_c._ Wind
_d._ Human Agency

C. LICHEN COMMUNITIES 362

1. ARBOREAL 363
_a._ Epiphyllous
_b._ Corticolous
_c._ Lignicolous

2. TERRICOLOUS 367
_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