UNIVERSITY STUDIES 



VOL. XVII JANUARY 1917 No. i 



'A STUDY OF THE VEGETATION OF SOUTHEASTERN 

 WASHINGTON AND ADJACENT IDAHO I 



A <\ 

 BY J. E. WEAVER 



TABLE OF CONTENTS 



PAGE 



Introduction 2 



Extent and position of area 4 



Physiographic regions and geology 4 



Soils 6 



Topography and drainage 8 



General plant-life conditions 12 



General veget'ational distribution 15 



Outline of developmental series 19 



Evaporation and soil moisture in relation to succession 21 



Soil temperature in relation to succession 37 



The prairie-plains formation 40 



Agropyron-Festuca association 40 



Festuca consociation 42 



Agropyron consociation 59 



Rhizocarpon-Lecidea associes 63 



Gyrophora-Parmelia associes 65 



Grimmia-T ortula associes 65 



Poa-Polygonum associes 66 



The desert scrub formation 71 



Artemisia- Atriplex association 72 



Artemisia consociation 72 



The Pacific Coast forest formation 73 



Thuja-Tsuga association 74 



Symphoricarpos-Opulaster associes 75 



Pinus-Pseudotsuga associes 78 



Larix-Abies associes 83 



Thuja consociation 88 



I 



