CONTENTS 



Page 



Introductory 33 



General description of the region and location of the ecological stations 35 



I. General description of the region 35 



II. The ecological stations 38 



Description of the prairie habitats and animals 40-56 



I. Prairie area north of Charleston, Station 1 40 



1. Colony of swamp grasses (Spartina and Elym.us), Station I, a. . 41 



2. Colony of wild rye, Ehfmus virginicus siibmuticus, Station I, c. . 43 



3. Wet area of swamp milkweed (Asclepias incarnata), Station I, d 44 



4. Cone-flower and rosin-weed colony, Station I, e 48 



5. Colony of bine stem (Andropogon) and drop-seed (Sporobulus), 



bordered by swamp milkweed, Station I, g 49 



6. Supplementary collections from Station 1 52 



II. Prairie area near Loxa, Illinois, Station II 52 



III. Prairie area east of Charleston, Station III 55 



Description of the forest habitats and animals 56-66 



1. The Bates woods, Station IV 56 



2. The upland oak-hickory forest, Station IV, a 57 



3. Embarras valley and ravine slopes, forested by the oak-hickory 



association, Station IV, b 59 



4. Lowland or ' ' second bottom, ' ' red oak-elm-sugar maple wood- 



land association, Station IV, c 62 



5. Supplementary collections from the Bates woods, Station IV. . . . 65 



6. Small temporary stream in the south ravine, Station IA r , d 65 



General characteristics of the gross environment 66-102 



1. Topography and soils of the State 66 



2. Climatic conditions 67 



3. Climatic centers of influence 69 



4. Relative humidity and evaporating power of the air 71 



5. Temperature relations in the open and in forests 83 



6. Soil moisture and its relation to vegetation S6 



7. Ventilation of land habitats 88 



8. The tree trunk as a habitat 91 



9. Prairie and forest vegetation and animal life 91 



10. Sources and role of water used by prairie and forest animals. ... 98 



Animal associations of the prairie and the forest 102-158 



I. Introduction 102 



II. The prairie association 103 



1. Swamp prairie association 103 



2. The cottonwood community 105 



3. Swamp-grass association 107 



4. Low prairie association 108 



5. Upland prairie association 109 



6. The Solidago community 109 



7. Dry prairie grass association Ill 



8. A milkweed community 112 



III. Relation of prairie animals to their environment 113 



1. The black soil prairie community 114 



2. The prairie vegetation community 117 



4. Interrelations within the prairie association 119 



