426 THE INVESTIGATION OF SUCCESSION. 



able aid in tracing the differentiation of the flora of an era into climaxes, and 

 the migrations of genera and species during a clisere. To serve this purpose, 

 however, it must be modified to take account of existing differences of composi- 

 tion and structure due to development. 



Raunkiaer (1905; 1910:171; c/. Smith, 1913:16) has established a new 

 system of life-forms or growth-forms based primarily upon the nature and 

 degree of bud protection during the tmfavorable season of the year. The 

 author justly regards the use of a single criterion as more satisfactory in that it 

 ^ permits definite comparisons, and enables one to correlate life-forms and 

 climate much more accurately. The analysis of the flora of any region into 

 its life-forms gives a biologic or phyto-climaiic spedrum, which is compared with 

 a theoretical norm called the normal spectrum. This method is also applicable 

 in some degree to communities in connection with Raunkiaer's use of the list 

 quadrat (1909 : 20), later modified into a circle (1912 : 45). This has the 

 advantages and disadvantages of the list quadrat, but its chief drawback lies 

 in its failure to take account of succession. Its values are floristic alone, and 

 the intensive worker will quickly pass to the more thoroughgoing methods of 

 quadrating. 



Chart quadrat. — Chart quadrats differ from permanent and denuded ones 

 which are also recorded in charts, only in the fact that they are not fixed and 

 visited from year to year. The manner of charting is the same in all (Clements 

 1905 : 167; 1907 : 206). The area desired, usually a meter or 10 meters, is 

 staked out by means of quadrat tapes a centimeter wide and divided into cen- 

 timeters, with eyelets at decimeter or meter intervals (plate 61 b). The 

 tapes are fixed by means of wire stakes, with loops at the upper end by which 

 they are readily moved. The end tapes are placed to read from left to right, 

 and the side tapes from top to bottom. After the quadrat is squared, the 

 bottom tape is placed parallel to the top one, thus inclosing a strip a decimeter 

 or meter wide for charting. This is charted decuneter by decimeter from left 

 to right, and the upper tape is then moved to mark out the second strip for 

 charting. The two cross-tapes are alternated in this fashion imtil the entire 

 quadrat is plotted. 



Special quadrat sheets are used for plotting (figs. 46, 47), which is always 

 begun at the upper left-hand comer of the chart, the small squares aiding in 

 determining the proper location of every plant. Each individual is indicated 

 whenever possible, but mats, turfs, mosses, and thallus plants are outlined in 

 mass as a rule. This is also done with large rosettes, bunches, and mats, 

 even when they are single plants. Each plant is represented by the initial 

 letters of the name. Signs may be used (Thomber, 1901 : 29), but they make 

 charts difficult to grasp, and have the great handicap of differing for every 

 investigator. The first letter of the generic name is used if no other genus 

 found in the same quadrat or series of quadrats begins with the same letter. 

 If two or more genera have the same initial, e. g., Agropyrum, Allium, and 

 Anemone, the most abundant one is designated by a, and the others by the 

 first two letters, as al, an. When a similarity in names would require three 

 or more letters, e. g., Androsace, Anemone, and Antennaria, this is avoided by 

 fixmg upon an arbitrary abbreviation for one, viz, at. The number of stems 

 from one base is often indicated by the use of an exponent, e. g., a^ Seedhngs 

 are often distinguished by a line drawn horizontally through the letter, and 



