270 APPENDIX 



associations but a great deal may also be done by observation alone. 

 In most localities a considerable amount of time can be given to this 

 phase of the work. In this as in all ecological work it is necessary 

 for the students to know the names of the plants concerned and there 

 is always a question as to how much time should be devoted to 

 systematic or taxonomic studies. The amount varies with the total 

 amount of time available for class use but as a rule the ability to use 

 keys for plant determination should be acquired in other courses 

 rather than in ecology. At any rate it is much better to simply tell 

 the students what the plants are than to sacrifice real ecological 

 studies to the work of identification. 



Suggested Problems 



1. To discover how many layers of vegetation may be found in a 

 forest and to determine the subdominant species of each. 



2. To discover what plant societies are present in certain local 

 associations. 



3. To describe in detail the structure of a given association. 



4. To compare "uplands" and "bottomlands" as to characteristic 

 tree species. 



5. To discover whether there is any correlation between soil 

 types and the local distribution of vegetation. 



Plant Succession.— The studies that may be made on plant suc- 

 cession will vary greatly with local conditions. Usually some early 

 stages can be found on rock outcrops or on areas that have been 

 denuded by erosion or by man, perhaps in the construction of a 

 drainage ditch, or some other agency. Even an ant-hill or the soil 

 thrown out around a woodchuck hole may be made to serve a valu- 

 able purpose. Usually also some examples of "zonation" may be 

 found, each zone of vegetation representing a stage in a sere. This 

 is especially well shown around ponds or lakes but may frequently 

 be found also along streams. If coal-mining striplands, or sand- 

 dune areas, or rock ravines, are available the class will be unusually 

 fortunate. 



Suggested Problems 



1. To work out the hydrosere of an inland lake. 



2. To discover what plants are the pioneer species on bare rock. 



3. To outline the succession that takes place on an area denuded 

 bv the activitv of man. 



