THE PEAT MOORS OF LONSDALE. 



AN INTRODUCTION. 



W. MUNN RANKIN, M.Sc. (Leeds), B.Sc.(LoNU.). 



{Continued from page 122). 



These many floral associations ranging between the open 

 water associations and the often broad bordering meadows of 

 Molinia, may be regarded as expressions of certain well- 

 defined physical factors operating beneath the vegetation, which 

 in no small measure is dependent vipon them. In addition to 

 the group of physical factors considered as resident within the 

 station, and operative upon livmg forms, selecting and modifying 

 perhaps, and thus made visible, there are those factors, also 

 having effect upon the constitution of a floral association, which 

 arise out of the presence of individuals of the same and different 

 species, namely those of biological competition. Considering 

 the association kinetically, it is seen to be a congeries of 

 very many factors, which it would be difficult, if not impossible, 

 to evaluate. Yet, as judged by the results, the group of factors 

 of the station are of the iirst importance ; as they vary, so the 

 plant association through which they work, undergoes change- 

 also. The physical characteristics of the soil, its moisture, 

 temperature, inorganic and organic composition, regarded at a 

 particular spot, are continually changing. As a consequence, 

 the complexion of the floral covering is steadily varying. Thus 

 taking our example of the lake side associations in passing 

 from the open water to the closed grass meadows on the opposite 

 limit of the swamp, there is a more or less steady decrease in the 

 percentage of water within the soil, accompanied by a change 

 in the composition of the dissolved compounds as well as by 

 variations in the factors of the soil consequent upon these. 



This zonation of physical factors is expressive of the succes- 

 sion of the same factors above a particular spot. The region of 

 open water near the reed-belt will, under favourable conditions, 

 in time itself pass under the condition of the reed-belt, and later 

 of the other zones. This change in the physical conditions of a 

 spot due in the main to the accumulation of plant debris or 

 peat, is expressed in the vegetation as a succession of plant 

 associations. This succession is, under favourable conditions, 

 recorded in the different strata of the peat. And in general, 

 this vertical succession will correspond closely to the lateral 

 zonation, though it must be noted that on the outer limits, 



191U Apl. I. L 



