PAPERS PRESENTED AT GENERAL SESSIONS 59 



presence of sphagnum and plants of xeromorphic char- 

 acter. As is well known, the plants are all of the low- 

 growing, dwarf habit, with many of them of cushion 

 forms which retain their dead leaves and structures for 

 some time. The flowers, tho small, are exquisitely vivid, 

 even more beautiful than members of the same genera 

 which are familiar in this region, such as DodecatheOn, 

 Myosotis, and so forth. 



Warming, in his Oecology, describes the fell fields, the 

 moss tundra, the lichen tundra, and the dwarf shrub 

 heath of Arctic regions; and he indicates the water 

 relationships of these by putting the moss association as 

 following the fell fields when the mosses gain the ascend- 

 ency, and the lichens as inhabiting the drier portions of 

 any of these associations. Since then no work has been 

 done to determine any further ecological relationships 

 between these associations, tho a great deal has been 

 done toward collection and identification of Arctic spe- 

 cies. In the time that was possible the attention of the 

 writer was directed toward the relationships and loca- 

 tion of different type associations. But these observa- 

 tions can be regarded only as preliminary, almost as 

 merely casual, for they were made over a very limited 

 area, and also under atypical weather conditions. They 

 make no claim other than to be just suggestive. 



The types of tundra observed by the writer were (1) 

 pioneer lichen associations, (2) open dwarf shrub asso- 

 ciations, (3) closed dwarf shrub associations, (4) Carex- 

 Eriophorum associations, (5) Spagnum-willow associa- 

 tions, and (6) the grass associations of the flood plains. 

 The most important factor in influencing the rate of suc- 

 cession between these associations is apparently the 

 wind, as the climate is apparently humid enough for the 

 support of mesophytic forms. After the accumulation 

 of humus by the early stages the water relations are 

 affected by drainage, for the freezing of the peat deposits 

 below prevents drainage and creates conditions produc- 

 tive of zeromorphic plant forms; but seepage of water 

 from higher land above the peat tends to keep the sub- 

 stratum thawed and gives rise to swampy conditions 

 described below in the Sphagnum-willow association. 



