328 



PLANT SOCIOLOGY 



Among the stupendous syngenetical experiments that are now going 

 on is the stabihzation and forestation of the forbidding stretch of 

 wandering dunes southward of Cape Sim on the Moroccan coast 

 (see p. 153) the outcome of which will decide the fate of the flourishing 

 commercial city of Mogador (Fig. 163). An equally gigantic 

 syngenetical experiment of a very different sort is the successional 

 study of the area exposed by the drjdng up and utilization for agri- 

 culture of the Zuider Zee, a scheme that is being carried forward by a 

 special commission under the direction of the Dutch ecologist De 

 Leeuw. 



3. Methods of Syngenetic Research. — Since Clements (1905) first 

 demonstrated the use of permanent quadrats, students everywhere 



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Fig. 164. — Permanent quadrat (1 sq. m.); examined in open prairie in 1916 (left) 

 and 1918 (right) B., Bouteloua oligostachya; E., Euphorbia serpens; Er., Eragrostis pectt 

 nacea; H., Helianthus subrhomboideus; L., Laciniaria punctata; O., Onagra biennis; P., 

 Physalis heterophylla; Pa.,Panicuin capillare; S., Solidago missouriensis; So., Sorghastrum 

 avcnaceum; Sp., Sporobolus longifolius; St., Stipa spartea. {After Weaver.) 



have been following the actual course of succession by means of per- 

 manent areas of which from time to time minute records are made 

 (Figs. 5, 6, 164, 165). Such studies are much enriched if, in addition to 

 recording the periodic exchange in the floristic composition of the 

 vegetation of these permanent areas, measurements of the principal 

 ecological factors are frequently made. The syngenetic effect of a 

 definite factor can be studied if one keeps all the factors constant except 

 the one which is subjected to measured modifications. 



The boundaries of small, permanent areas should be marked by an 

 iron wire pegged to the ground. For larger areas colored boundary 

 marks on trees and rocks are used. A general map should always be 

 made, and when possible the area should be photographed from a 



