Periodical Literattire 141 



openings experiences only a small addition of species and individ- 

 uals, while in tolerant species with increasing opening both num- 

 ber of species and of individuals are considerably increased. 



With increased opening and hence denser soil vegetation com- 

 petition among the species begins, and finally, certain species 

 remaining victors (those which are able to form a felty mat) the 

 composition changes at least in numerical direction. These weeds 

 are to the silvculturist the most objectionable, as they prevent 

 regeneration ; and to cope with them is his greatest problem, 

 in the solution of which underplanting may play a part. 



Finally the author discusses the question whe^ice comes this soil 

 flora so quickly after the crown cover has been opeyied f The theory 

 of its origin from seeds lying dormant in the ground has been long 

 held, and A. Peters, some 13 years ago, attempted to prove this 

 experimentally. The experiments consisted in exposing old for- 

 est soil and farm soil that had been reforested to conditions favor- 

 able to the germination of whatever seeds might be found in them. 

 The former produced almost only forest weeds, the latter mainly 

 farm weeds, and Peters concluded that the seeds had remained 

 germinative for 22 and 46 years. This Cieslar doubts, be- 

 lieving that the facts do not warrant or require this explanation. 

 Analyzing the case of the 22-year-old plantation, assuming 3-year 

 old plant material the spruces had been in place 18 years, but 

 they had probably not closed up until 12 to 15 years after planting, 

 so that only 3 to 6 years of retention of germinative power would 

 have been required. Moreover, a large number of the plants de- 

 veloped were perennials which are known to be able to preserve 

 rhizomes and roots alive. Moreover it is known that many an- 

 nuals and biennials growing under conditions which render flower- 

 ing and fructification difficult or impossible become perennial, and 

 this occurs often in shady woods. 



The second series of Peters came from a 46-year-old larch 

 stand. While pure larch stands close up in the second decade 

 so dense that the green soil cover vanishes, this dense crown cover 

 does not last long, and by the fourth decade such stands thin out 

 naturally so that phanerogamic life probably never ceases in them. 



A third series of Peters came from a 100-year-old beech stand. 

 The 1 1 species produced prove with one exception to be not only 

 perennials, propagating by rhizomes and sprouting, but their 

 flowering occurs during the leafless period of the beech, hence 

 they complete their cycle before the shade influence sets in ; more- 



