THE DECIDUOUS FOREST CLIMAX. 213 



abandoned fields the preliminary herbaceous stages are omitted when a plowed 

 field near a mature stand of trees happens to be abandoned in a heavy seed 

 year. In other cases the herbaceous stages are present but temporary, while 

 in the case of pastured areas the sod-forming grasses persist for a much longer 

 time before the trees return. The white pine gradually regains control in 

 such abandoned fields by direct re-seeding, by supplanting white birch, and 

 by the replacement of pitch-piae stands. 



Dachnowski {1912)has studied the secondary succession afterfirein peat-bogs: 



Where the burn is sHght, many new shoots arise from the rhizomes of 

 Aspidium, Osmunda cinnamomea, and 0. regalis. These are followed by 

 Aronia, Nemopanthes, Vacdnium corymbosum, etc. In places where the fire 

 was severe these species do not occur, and such areas are dominated by 

 Urtica, Impatiens, Typha, and Sdrpus cyperinus, with which are mingled 

 Oenothera biennis, Epilohium color atum, Euonymus, Polygonum, Solidago, etc. 

 Repeated fires change the marshes into grassy prairies dotted with sharply 

 defined clumps of trees and bushes. Bidens trichosperma. Verbena hastata, 

 and Ambrosia trifida dominate in areas severely burned, while Eupatorium 

 perfoliatum, Solidago canadensis, and Carex lurida are less abundant. In 

 areas of light surface fires the principal plants are the ferns already mentioned, 

 Eriophorum virgiriicum, Rhynchospora alba, and Juncus canadensis, among 

 which are scattered shrubs and trees, Rhus, Rosa, Spiraea, Aronia, Salix dis- \ 

 color, Popvlus heterophylla, and P. tremuloides. In lower places, Phragmites i 

 and Calamagrostis form conspicuous communities. The climax stage con- 

 sists of an Acer-Ulmus forest. 



Conard (1913 : 80) has given an account of the colonization of a secondary 

 area, consisting of a wide shelf formed by road-making: 



"This digging was done in March and April 1911, and in July 1911 many 

 plants were well developed on the apparently denuded area. The new flora 

 of the shelf consists of 60 species of angiosperms and one fern (Pteris aquilina) ; 

 53 of these grow on the hillside above the sheK. Of the plants found both 

 above and below, 39 are long-lived perennials, growing in the new groimd 

 from pieces of root, rhizome, or entire plants carried down from the hillside. 

 Of those growing as seedlings, 6 species of the new groxmd were not found on 

 the hillside, while on the hOlside there are 25 species not yet represented on 

 the new ground below; some interesting questions arise from consideration 

 of both classes. 



"The author's main conclusions are that (1) an area denuded in winter or 

 early spring receives few or no disseminules by any agency save that of man 

 or domestic animals, since plants are not travelmg at that season; (2) an 

 apparently denuded area may contain viable fragments of a rather large flora; 

 (3) if the disturbance occurs during the resting period of vegetation, new plants 

 will arise from many fragments that would perish at any other season, since 

 the resting plant contams stored food to enable it to start new growth, and 

 most perennials put out a whole new system of absorptive roots as well as 

 whole new foliage each year, the extent of the new root system being greater 

 than is sometimes supposed." 



Cooper (1913 : 232) gives the following summary of the burn subsere on 

 Isle Royale: 



"The effect of fire upon the climax forest is to bring about a return to a 

 more or less xerophytic condition, which is followed by a readvance leading 

 to the climax. Two general cases may be distinguished. 



