The role of Dryas drummondii in vegetation development following ice recession at Glacier Bay, Alaska, with special reference to its nitrogen fixation by root nodules
Lawrence DB, Schoenike RE, Quispel A, Bond G. 1967. The role of Dryas drummondii in vegetation development following ice recession at Glacier Bay, Alaska, with special reference to its nitrogen fixation by root nodules. Journal of Ecology. 55(3):793-813
The development of vegetation on newly deglaciated terrain exposed in the last 200 years is of fundamental importance to students of the Pleistocene in interpreting vegetation change since the retreat of the continental ice sheets. Glacier Bay, Alaska, is well suited for these investigations since the rate of recession of glaciers there is probably more rapid than anywhere else in the world. Earlier studies at Glacier Bay focused attention on the floristic elements of the successional communities and on the rate at which succession was progressing, while later studies dealt with parallel trends in soil development and in the activity of fungi. These studies show that the advance of the ecosystem is governed mainly by the amount of nitrogen that it contains and the rate of its circulation through the system. Dryas drummondii Richards. is the first plant species to attain dominance on the deglaciated areas, and holds that position for 20-40 years. Its vigorous growth and fertility, contrasting sharply with the depauperate growth of most other pioneers, are facilitated by the presence on the Dryas of root nodules which are shown by rigorous greenhouse and laboratory tests to fix atmospheric nitrogen on a considerable scale. The nodules are shown to resemble those of Alnus and of some other non-leguminous genera in structure and in the appearance of the nodular endophyte. During the period of dominance of Dryas the nitrogen content of the soil-plant system increases from 33 kg/ha to some 400 kg/ha. Tree species, notably Populus trichocarpa, are shown to grow better in Dryas-covered areas than in others where Dryas is absent. Similar growth responses were elicited in the Populus saplings by application of nitrogenous fertilizers. Dryas is, however, considerably less effective in building up nitrogen in the ecosystem than Alnus, the succeeding plant community, and it is only the latter that raises the nitrogen supply to a level enabling the spruce forest to achieve dominance.
- Type
- Journal Article
- Authors
- Lawrence, D; Schoenike, R; Quispel, A; Bond, G
- Units
- GLBA
- Keywords
- Alaska, Cenozoic, Chronosequence, deglaciated terrain, Ecology, Forest, Geomorphology, Glacial Features, Glacier Bay, Nutrients, Paleoecology, Quaternary, Soils, Succession, Terrestrial, Vegetation, vegetation development, vegetation effects